Archive for the 'species interactions' Category

Apr 16 2010

Mangroves: More To It Than Meets The Eye…

Published by under species interactions

You may have seen mangroves somewhere along the coastal area of Singapore but what are the significances of those mangroves? Just after doing some research before writing this blog that I realized mangroves have profound significances to coastal ecosystems in Singapore. For instance, along the coast of Chek Jawa, you can observe mangroves , e.g. Bakau minyak (Rhizopora apiculata) and api-api bulu (Avicennia rumphiana) growing at the intertidal zone.

Bakau Minyak

Bakau Minyak (photos from WildSingapore, Flickr)

Api-api bulu

Api-api bulu, another common mangrove species found at Chek Jawa (photos by WildSingapore, Flickr)

Mangroves support over 150 species of fish in Singapore (Lim K.P. Kelvin et al., 1999). Estuarine catfish (Mystus gulio) is a common example.

Estuarine catfish

Estuarine catfish (Retrieved from "A Guide to Mangroves of Singapore" by Peter Kelvin K.P.Lim et al., 1999)

One of the most important roles of mangroves is nursery habitats for juvenile fish. You may ask why mangroves are so attractive to fish, especially juvenile fish. The reasons for this question include 2 major factors,i.e. food abundance and protection from predators. The epiphytic  algae on mangroves pneumatophores accumulate an assemblage of invertebrate species, thus providing ample food supply to fish (Low and Chou, 1994). The structure of mangrove habitats also provides protection and shelter from predators to juvenile fish.

Another important role of mangroves is that mangroves bind soft sediments, facilitating coral reef development in areas that might otherwise have too much silt for coral growth. In turn, coral reefs buffer wave impacts, helping to minimize erosion of soft sediments that mangroves need to grow (Mumby et al., 2004). 

References:

Low, J.K.Y, Chou, L.M.1994. Fish diversity of Singapore mangroves and the effect of habitat management. Research Paper, Third ASEAN-Australia symposium on living coastal resources Vol.2 (pp.465-470). Bangkok: Chulalungkorn University.

Lim, K.P. Kelvin et al. 1999. A Guide to Mangroves of Singapore. Singapore Science Centre.

Second sources:

Mumby, P.J. et al. 2004. Mangroves enhance the biomass of coral reef fish communities in the Carribean. Nature 427: 533-536.

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Apr 16 2010

Fig Tree and Fig Wasp = Babysitter and Matchmaker

Published by under species interactions

Figs fruiting from trunk. (Photograph © Nick Baker)

Figs fruiting from trunk. (Photograph © Nick Baker)

Fig trees (Ficus sp.) are considered as a keystone species in Singapore rainforest. This is because they flower and fruit frequently, offering frugivorous animals a year-round supply of food. The figs are actually an enclosed inflorescence known as syconium, within which a unique mutualistic relationship between the plants and fig wasps take place. Fig wasp is a tiny insect from the Agaonidae family which lays its eggs in the syconium.  

 

Upon hatching, the larvae will grow and develop inside the syconium with protection and immediate food provided by the fig. It is also within this small syconium, the grown up wasps mate. The female wasps carrying fertilized eggs will then leave the syconium with the assistance of the wingless male wasps which chew a hole through the syconium wall and subsequently die without leaving the syconium (Cook & Rasplus, 2003).

 

In return for the shelter and food, the female wasps act as pollinators for the fig tree. This is because a female wasp often picks up pollen from the male flowers in its home syconium. After leaving its home syconium, the female wasp will look for another syconium to lay its eggs and eventually they pollinate the female flower within (Tan, Chou, Yeo & Ng, 2010).

 

Figure 1: Life cycle of fig wasp (Agaonid)

Figure 1: Life cycle of fig wasp (Photograph © Encyclopædia Britannica)

 

The mutualistic relationship between figs tree and fig wasp is co-evolutional and highly obligated. Each fig species generally has its own agaonid symbiont as pollinator; the wasp on the other side is host-specific. This can be revealed by the inability of a fig species to colonize a new habitat without its specific pollinator wasp species being established (Ramirez, 1970). The specificity is advantageous to both fig trees and fig wasps. This is because it reduces inter-species competition for syconia while increase the chance of successful pollination of fig trees.

 

 

References:

 

  1. William Ramirez B., 1970. Host Specificity of Fig Wasps (Agaonidae). Evolution, 24(4): 680-691.
  2. Cook, J.M., Rasplus, J.Y., 2003. Mutualists with attitude: coevolving fig wasps and figs. Trends in Ecology and Evolution. 18: 241-248
  3. Hugh Tan T.W., Chou L. M., Darren Yeo C. J, Peter Ng K. L., 2010. Primary Vegetation. The Natural Heritage of Singapore. Singapore: Pearson Education South Asia Pte Ltd.
  4. “Fig Wasp” by Encyclopædia Britannica, 1999. URL: http://www.britannica.com/EBchecked/topic-art/206044/19378/The-life-cycle-of-the-fig-wasp (accessed on 15 Apr 2010)
  5. “Bukit Timah Nature Reseve- a precious remnant of primary rainforest” by Nick Baker. Ecology Asia, 2010. URL: http://www.ecologyasia.com/html-loc/bukit-timah.htm (accessed on 14 Apr 2010)

 

Second Sources:

  1. Wiebes, J. T., 1979. Co-Evolution of Figs and their Insect Pollinators. Annual Review of Ecology and Systematics, 10: 1-12

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Apr 16 2010

Spotted: Weaver ants trying to tear apart a live Honey Bee

black dwarf honey bees

Figure 1: Black honey dwarf bees.

Black dwarf honey bees (Apis andreniformis) were spotted collecting nectar in a Powderpuff tree (Calliandra emarginata). On a closer look, the bees also shared the tree with some Weaver red ants (Oecophylla smaragdina), as well as other small black pollinating midges (c.f. Family Ceratopogonidae or Cecidomyiidae).

Firgure 1: Weaver ants hoisting motionless bees back to their arboreal nests.ants: "yummy. another dead bee."

Figures 2 and 3: In two other nearby trees: Weaver ants hoisting motionless bees back to their arboreal nests.

I had assumed that although these  ants look intimidating, they play a vital role in helping to speed up the decomposition of dead matter (i.e. nature’s clean-up crew as seen above), and are therefore mostly scavengers. Little did I know that these ants we commonly see outdoors can be very voracious predators. They may just be on the lookout for their next sizable prey, whether dead or alive.

Weaver ants each holding onto a different point of the bee. They seem to be pulling and trying to contort the bee.

Figure 4: Weaver ants each holding onto a different point of the bee. They seem to be pulling and trying to contort the bee. (Black arrow: Was that a part of the bee?)

As I took a closer look at the first tree which was busiest with bees (as in Figure 1), I spotted a commotion on one of the branches (Figure 4 on the left). I thought the bee was dead — but it buzzed briefly and was held down by the weaver ants.

Weaver ants have been documented to kill prey by stretching it, and simultaneously concealing them with twigs and leaves, or retrieving them back to their arboreal nests, to prevent other predators from snatching their prey (Rastogi 2000).

I was appalled, but it also puzzled me how these light-weight ants could hold onto a bee attempting to escape. It turns out that the limb ends of these ants are specialized to resist detachment up to 150 times their own weight  (Federle et. al. 2002):

Light micrographs of how a weaver ant’s pre-tarsus (limb end) grabs onto a surface. As the limb is pulled downwards, the adhesive cuticle pad (between the pre-tarsal claws) expands automatically, creating a suction-adhesion force. (Figure 2 in: Federle et. al. 2002)

Light micrographs of how a weaver ant’s pre-tarsus (limb end) grabs onto a surface. The cuticle pad (between the pre-tarsal claws) creates a suction-adhesion force. This adaptation enables them to forcefully pull in neighbouring leaves while standing on smooth leaf surfaces (can be seen in action in Figure 4). (Figure 2 in: Federle et. al. 2002)

tree trunk crawling with weaver ants

Figure 5.

Out of the several Powerpuff Powderpuff trees present, only that one tree was busiest with bees. Bees being endotherms, perhaps they preferentially extract nectar from trees receiving the most sunlight (Young 1985). However on closer inspection of the adjacent tree ( with visibly less bee activity) — I found another possible reason — the branches were colonised by weaver ants (see Figure 5).

Witnessing how a weakened bee had been held captive by the weaver ants in a case of power in numbers, it’s no wonder that the tree barely had any bee visitors (refer to: Ritter and Akratanakul 2006, Junker et. al. 2006 ).

A weaver ant showing aggression at the honey bee.

A Weaver ant showing aggression at a Black dwarf honey bee (seen by exposing its mandibles).

Seems like these ants not only deter herbivores in a mutualistic relationship with its host tree (as mentioned in fellow course-mate u0805142’s blogpost), they also deter pollinators (Ness 2006, Tsuji et. al. 2004). These ants have certainly more to them than meets the eye.

ants

Weaver ants standing gaurd, and on the lookout.

References:

  • Young, A. M., 1985, Pollen-collecting by stingless bees on cacao flowers, Cellular and Molecular Life Sciences, 41(6):760-762
  • Rastogi, N. 2000, Prey concealment and spatiotemporal patrolling behavior of the Indian tree ant Oecophylla smaragdina (Fabricius), Insectes Sociaux, 47(1):92-93
  • Federle, W., Riehle, M., Curtis, A. S. G., Full, R.J., 2002, An Integrative Study of Insect Adhesion: Mechanics and Wet Adhesion of Pretarsal Pads in Ants, Integrative and Comparative Biology 42(6): 1100-1106.
  • Ness, J. H., 2006, A mutualism’s indirect costs: the most aggressive plant bodyguards also deter pollinators, Oikos, 113(3): 506-514
  • Tsuji, K., Hasyim, A., Harlion & Nakamura, K. ,2004, Asian weaver ants, Oecophylla smaragdina, and their repelling of pollinators. Ecological Research, 19(6): 669-673
  • Ritter, W. & Akratanakul, P., 2006, Honey bee diseases and pests:a practical guide, FAO (Food and Agriculture Organization of the United Nations) agricultural and food engineering technical reports, p20. Retrieved April 12, 2010 from : http://www.fao.org/AG/ags/subjects/en/industFoodAg/pdf/AGST_techrep_4.pdf
  • Junker, R., Chung, A. Y. C., Blüthgen, N., 2006, Interaction between flowers, ants and pollinators: additional evidence for floral repellence against ants. Ecological Research,22(4):665–670.

( Coloured photographs used in this post are taken by the author on 11th and 12th April 2010)

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Apr 16 2010

Crab eat Crab

Published by under species interactions

Who would have thought that a crab could devour another crab more than half its size? Certainly not a largely algivorous Purple Climber Crab!

Picture taken in Pulau Semakau

Picture taken in Pulau Semakau, 28th March 2010

Being an opportunistic predator inhabiting the sea-ward mangrove fringe, the Purple Climber Crab, Metopograpsus spp., is occasionally known to incorporate smaller crabs as part of their diet (Poon & Chan, 2009). Shown in the picture below is an example of such an occurrence. What is thought to be a soldier crab (Mictyris brevidactylus) was struggling in the grip of the distinct purple pincers of the climber crab, a vice of which is known to be better suited to scrap off algae (Ng & Sivasothi, 2001).

This crab’s dietary pattern is shaped by the interplay between its biology and physical environment (Poon & Chan, 2009). Having spoon-shaped chelae efficient for browsing filamentous macroalgae or scraping off biofilm from substrates, it is little wonder than its diet is dominated by algae. However, the purple climbing crab will attack any prey it can overcome given its highly opportunistic nature.

Habitats with a four-seasonal variation also influence the crab’s diet. An example would be in Hong Kong, where winters reduce the wandering activity of the soldier crab and winter bloom of ephemeral macroalgae, result in the consumption of more algal material. Summers see the opposite happening (Poon & Chan, 2009).

The opportunistic nature of the crab can be likened to that of other animals such as humans, leopards or dogs, which are able to kill and eat almost anything. It is thus little wonder that the crab can survive well on the dynamic shores of Pulau Semakau!

References

Ng, P. K., & Sivasothi, N. (2001). purple climber crabs. Retrieved from Guide to Mangroves of Singapore: http://mangrove.nus.edu.sg/guidebooks/text/2047.htm

Poon, D. Y., & Chan, B. K. (2009). Spatial and temporal variation in diets of the crabs. Springer Science , Hydrobiologia (2010) 638:29–40.

Second Source

Poon, D. Y., & Chan, B. K. (2009). Spatial and temporal variation in diets of the crabs. Springer Science , Hydrobiologia (2010) 638:29–40.

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Apr 15 2010

Here Kitty, Kitty!

Published by under species interactions


Whenever I tell someone I own 4 cats, I’m often met with a look of concealed surprise before they say, “Oh, well… that’s…umm…nice?” which not-so-secretly translates to “Oh my god, she’s one of those crazy cat-ladies!” After countless futile attempts at trying to defend my reputation, it got me thinking, why keep pets in the first place?

What type of symbiosis exists between humans and their pets?

What type of symbiosis exists between humans and their pets?

Singaporeans may not be well-versed in the flora and fauna of Singapore, but we do love the idea of animals in the form of pets. Pets are popular in Singapore, the thriving pet shop industry being a testament to that. Stray animals, have also increased with abandoned animals being a majority of the animals the local SPCA takes in.(SPCA, 2009) People often take in animals, subconsciously expecting the relationship to be mutualisitic. What they fail to realise is that symbiosis between human and animals is never clear-cut mutualism, especially when it comes to cats.


More of Commensalism than Mutualism

Symbiotic relationships between humans and their pets have often been called mutualistic, with humans providing their pets food and shelter, and the pet in turn providing companionship, food and transportation. (Heffner, 1999)

However, I believe, domesticated cats, Felis catus, especially in Singapore, often share a more commensalist symbiosis, with owners gaining no tangible benefit from the cat.* Cats can’t provide us food nor transportation and only offer the ecologically less tangible benefit of love and companionship (Archer, 1997). Singapore’s urbanised, compact environment, and strict government rules further enforce commensalism, as cats now depend on humans to even clean up after them. Because of this, owners often realise that cats take up too much of the time and energy, and then want out of the symbiosis.


Cleverly-disguised Parasitsm

Which brings me to examine the symbiosis my cats and I share. They expect me to provide them with food each time they arrive at their food bowls, jump on my laptop and books when I’m studying, get themselves into the various

"Where's my food?!"

"Where's my food?!"

ailments regularly, resulting in their vet being able to take a luxurious holiday annually, and scratch me if they deem me in their way. You would expect them to at least be affectionate, but nope, they avoid me whenever possible. They only allow themselves to be petted when they’re sleeping, and never when they’re eating. And most of all, they get to choose where they sleep, and never give it up, especially when its on favourite chair. Commensalism? Sounds more to me like parasitism, at the expense of my bank balance, furniture and sanity!


Nah, I was just kidding about the Parasitism Bit

As an aspiring biologist who understands the need for scientific objectivity, I know that I need way more evidence if I were to ever prove my hypothesis of parasitisim.  Hence I conclude, that the relationship between humans and pet cats, is more commensalistic, with the cats, of course, being the beneficial party. So why keep pets, you wonder? Because, each rare time, my cat(s) snuggle up to me (albeit because they just want a piece of the fish keropok I’m munching on), it does makes the whole symbiosis worthwhile. :)

"in other words, i win!"

"in other words, i win!"

*Disclaimer: This observation stems from 13 years of keeping cats, and from talking to other cat owners. This in no way reflects all symbiosis between humans and their pets. Cats are a different breed of pets, really.

All photos of cats in this post were taken by me.

***

References

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Apr 15 2010

Rusty trees around you?!

Published by under species interactions

One of the things that strike me ever since I came to Singapore is that it is truly a Garden City. ” No roads has been left uncovered and no vacant land within the city left unplanted with shrubs ( W.Y.Chin and C.Richard, 1986).” Thanks to those big trees on campus I am able to survive the intense heat of the sun. There is one interesting feature on the tree that you might have observed before as well.

P1020148A "rusty" tree I saw on the way to Science Faculty. Taken outside Raffles Hall.

Above: An algae covered tree in PGP Residences. Below: “Rusty” trees seen outside Raffles Hall of Residences.

 Take a good look on the trees, some of them have brownish orange patches on the bark. Some of the patches are so extended that the whole trunk actually look orange! It certainly is not the plant pigmentation as it appears on different species of trees and trees of the same species do not necessarily possess this feature. So the first though that crossed my mind was: ” can trees actually get rusty….?”
 

After a closer examination, the orangy stuffs that look powdery from far, actually appear to be quite rough. Some patches looks like a rough orange carpet covering the bark, while some looks somehow like overcompressed breadcrumbs. Now it looks like some fungus or lichen. Since this question has been bugging me, I decided to find out the identity of the rusty patches. 

Closed up: lichen-like green algae (Trentepohlia sp.) on a tree bark

Closed up: lichen-like green algae (Trentepohlia sp.) on a tree bark

So…. It appears that the rusty orange patches are actually green algae! It’s not uncommon that algae lives attached to the trees, but what surprised me more was that it is actually classified under GREEN algae! Green algae, phylum Chlorophyta, now belongs to a well-established monophyletic group, Viridiplantae, in which the terrestrial plants are also included. This species of green algae comes from the order Trentepholiales and the genus of filamentous green algae,  Trentepohlia. Algae under this order are usually subaerial algae which are adapted to live on substratum like natural rocks, concrete walls, plastic nets, tree barks, fruits and leaves (Rindi F. et.al., 2009). Some of the algae under this order are actually lichenised-algae. Trentepholiales attached to the subtrata via filamentous hyphae and reproduce via spores.

 

Closed up: rough crust-like Trentepohlia carpet on a tree trunk.

Closed up: rough crust-like Trentepohlia sp. carpet on a tree trunk.

Now why is it in the same family as the green algae while it appears to be orange? Algae of order Trentepohliales produce large amount of carotenoids (which is also a component of chlorophyll), such as beta carotenoids and haematochorome. These pigments gave the algae their charateristic bright yellowish orange or red colouration. Trentepohlia sp. is well distributed across the humid tropic region.

Since the algae has chlorophyll pigments hence the ability to photosynthesize and the host plants do not show any signs of malnutrition or being parasited, the interactions of these green algae with the tree most probably are commensalism. While for non-living substrata, I was thinking that it too, merely serve as a host. However, these green algae actually post problems to substratum like the concrete wall. Pigments produced by Trentepholia sp. caused local erosion like pitting and discoloration of wall when present as biofilm (Gaylarde P. et.al., 2006).  

Okay, doubts cleared. Hopefully next time when you stumble across some trees with strage orangy trunks, you will know that it is actually algae growings instead of rust !

 

References:

Hugh, T.W.Tan et.al.,2007,  The Natural Heritage of Singapore 2nd Edition. Prentice Hall, Pearson Education, South Asia Pte. Ltd. Singapore.

Corlett, R. and Chin W.Y., 1986, The City and The Forest: Plant Life in Urban Singapore. Singapore University Press, National University of Singapore.

Rindi F. et.al., 2009, An Overview of The Biodiversity and Biogeography of the Terrestrial Green Algae, Nova Science Publishers, Inc. http://bama.ua.edu/~dwlam/index_files/Rindi_Biodiversity%20hospots_PC.pdf (retrieved 10th April 2010)

Gaylarde P. et.al., 2006, Lichen-like colonies of pure Trentepohlia on limestone monuments, Elsevier Ltd. http://www.sciencedirect.com.libproxy1.nus.edu.sg/science (retrieved 10th April 2010)

Trentepohlia, Wikipedia.http://en.wikipedia.org/wiki/Trentepohlia (retrieved 14th April 2010)

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Apr 15 2010

Nemo’s crib

Published by under species interactions

Have you ever wondered how does Nemo‘s crib looks like? Here it is!

Giant carpet anemone

Giant carpet anemone - picture taken at Pulau Semakau

Underside of the giant carpet anemone

Underside of the giant carpet anemone - picture taken at Pulau Semakau

The giant carpet anemone, Stichodactyla gigantea, are commonly found in the shallow intertidal sand flats of Singapore’s southern shores. Usually growing up to 50cm in diameter, the S. gigantea is an opportunistic predator and scavenger.(R.Tan, 2009) It is capable of stinging and devour any fishes or invertebrates when brushed against its tentacles containing cnidocytes.(MarineBio.org, 2010) However, it also forms symbiotic relationship with other organisms such as zooxanthellae and false-clown anemonefish, generally the Amphiprion spp.

The False-clown anemonefish, Amphiprion ocellaris, is often seen to be associated with the giant carpet anemone in Singapore.(R.Tan, 2009) It resembles closely to the TRUE clownfish, Amphiprion percula, except that Percula has only 10 dorsal-fin spines while Ocellaris have 11.(MarineBio.org, 2010) Moreover, they also can be differentiated by their iris whereby Percula has orange iris that make their eyes look smaller and Ocellaris have orange-grey iris and make their eyes look bigger.

Amphiprion ocellaris

Amphiprion ocellaris - picture taken by Bictures, from photobucket

Amphiprion percula - taken by Jordan-to, from photobucket

Amphiprion percula - taken by Jordan-to, from photobucket

The interaction between A. ocellaris and S. gigantea is a form of mutualistic relationship whereby both parties benefit from one another. The S. gigantea provides the A. ocellaris and its clutch a shelter and protection from predators while the A. ocellaris provides protection to S. gigantea by chasing away anemone-eating fishes such as butterflyfish.(MarineBio.org, 2010) Moreover, A. ocellaris also helps to groom S. gigantea by getting rid of parasites and debris.(B. Berends, 2007) Furthermore, A. ocellaris indirectly provides a food source by luring fishes into the anemone or to excrete nitrogenous wastes for the photosynthetic zooxanthellae, which is an endosymbiont of the giant carpet anemone that shares the products of photosynthesis with its host. (E. Truelove, 2008)

References

E. Truelove. (2008). Mutualism between clownfish and anemone: Following my research at college of William & Mary. Retrieved on 14 April 2010, from http://clownfishandseaanemones.blogspot.com/

B. Berends. (2007). Interactions with other species. Retrieved on 14 April 2010, from http://bioweb.uwlax.edu/bio203/s2007/berends_bets/interactions.htm

Amphiprion ocellaris, Clown Anemonefish – MarineBio.org. Retrieved on 15 April 2010, from http://marinebio.org/species.asp?id=29.

R. Tan (2009) WILD Fact Sheets: Giant carpet anemone. Retrieved on 14 April 2010, from http://www.wildsingapore.com/wildfacts/cnidaria/actiniaria/gigantea.htm

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Apr 15 2010

An inter-species relationship – when love is reciprocated.

Published by under species interactions

The parent’s shelter may not always be the best for the child. This may be the most apt description for the clownfish (anemonefish), whose true protectors in the coral reef ecosystems are the sea anemones instead of their parents (Roach, 2003).

A mutualistic relationship is one where both partners of different species derive benefit from their interaction (Holbrook & Schmitt, 2005). Mutualism between the clownfish (Amphiprion sp.) and the sea anemones is one of the better-known examples of symbiosis that can be commonly seen on the southern shores of Singapore, such as on Kusu Island, Pulau Semakau and Sentosa.

Fig. 1: Our very own version of Nemo – the False clown anemonefish, Amphiprion ocellaris, living in the Giant carpet anemone (Stichodactyla gigantea).

Fig. 1: Our very own version of Nemo – the False clown anemonefish, Amphiprion ocellaris, living in the Giant carpet anemone (Stichodactyla gigantea). Location: Kusu Island. (Tan, 2004)

In general, what does each party stand to gain from the relationship?

For the clownfish, protection from their predators is one of the main advantages. The tentacles of sea anemones have nematocysts that deter contact by most fishes and other invertebrates, while the mucus coating on the clownfish prevents the nematocysts from discharging its stingers (Holbrook & Schmitt, 2005). Thus, a safe haven is created for the clownfish when it seeks refuge within the tentacles of the sea anemone. An additional benefit is the provision of a safe nest site by the sea anemone (Holbrook & Schmitt, 2005). Leftovers of prey captured by the host sea anemone may also serve as a source of food for the clownfish (Tan, 2008).

Fig. 2: Tomato anemonefish, Amphiprion frenatus, living in the  Bubble tip sea anemone (Entacmaea quadricolor).

Fig. 2: Tomato anemonefish, Amphiprion frenatus, living in the Bubble tip sea anemone (Entacmaea quadricolor). Location: Pulau Semakau. (Tan, 2008)

In return, the clownfish defends its host anemone from predators (Roach, 2003; Holbrook & Schmitt, 2005). The clownfish may also remove parasites, dead tissues and sediments from the anemone (Tan, 2008). In addition, there is the possibility that anemonefishes attract other fishes that are captured and eaten by the sea anemone (Tan, 2008). Sources of regenerated nitrogen, sulfur, and phosphorous can also be obtained if the sea anemone absorbs the wastes of the fish to gain additional nutritive benefits (Fautin, 1991; Holbrook & Schmitt, 2005).

Life is indeed enjoyable when love is reciprocated after all.

Literature cited

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Apr 14 2010

Alien VS Native

An example of how introduced species can affect the ecosystem as well as affect the population of the native species would be the introduction of changeable lizards into Singapore.

The changeable lizards (Calotes versicolor), as seen in picture below, are�the introduced species in Singapore while the�native species in Singapore are the green-crested lizard (Bronchocela cristaella). These changeable lizards originate from India, and Indochina, and were introduced into�Singapore in�the 1980s. They are now a common sight around the urban areas in Singapore.

Changeable lizard (Calotes versicolor)

The changeable lizard, Calotes versicolor, seen in its breeding colouration in NUS

These changeable lizards can be commonly found in managed parks and gardens, and can get very territorial especially during the breeding seasons. This sort of territorial behaviour was observed while taking the picture of the lizard in NUS where the lizard was displaying a “push up” action. When compared, the green-crested lizards inhibit the primary and secondary forest. It seems to be a competition for the native species, the green-crested lizard, as presence of the changeable lizards decreases the number of green-crested lizards that could be observed in parks and open areas before the alien species were introduced.

The changeable lizards are able to displace and out-compete as it is more aggressive than the green-crested lizards. This is rather evident based on observation because the changeable lizards are more commonly seen around within urban areas, managed parks and gardens (an example as seen in picture below).

Changeable lizard

Changeable lizard observed in a park

These changeable lizards are included in the list of invasive alien species in Southeast Asia (Tan and Tan, 2003). This form of competition posed by changeable lizards is also seen in other countries as well, for example in Florida, where this species of lizard was also introduced.

However, from another point of view, these changeable lizards may just be better at exploiting the habitat than the green-crested lizard. Since Singapore were experiencing rapid development around the time when these changeable lizards were introduced. It may be a case of exploitative competition by the changeable lizards. 

Reference:

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Apr 14 2010

Being Upside down isn’t bad all the time.

As i walked along the intertidal zones of Pulau Semakua, many forms of  ecological relationships can be identified on the shore and these interactions  includes competition, exploitative interaction, commensalism, herbivory and symbiosis. However , out of all the organism i saw during that trip, a weirdly oriented organism that seemed like a flower anemone caught my attention.

Upside down jelly fish taken on semakua island

Picture 1: Upside down jelly fish taken on semakua island

Although the Upside-down jellyfish, Cassiopea sp., had been observed many times on the shore of Pulau semakua , that was my very first encounter with one.  Many non-biologists will either often mistake the jelly fish as a sea anemone or will try to flip the jellyfish around (picture 2) thinking that is it not in the correct orientation. Actually, the Upside-down jelly fish is in the correct orientation. The reason the jellyfish has such an orientation is due to is symbiotic relationship with unicellular algae called zooxanthella (Karla C. arcia). Such an orientation allows and promote  the growth of the algae.(picture 1)

upperside of an upside down jelly fish taken from semakua

picture 2 :upperside of an upside down jelly fish taken from semakua

The zooxanthella resides in the bell of the jellyfish and provides the jellyfish with an important carbon source through photosynthesis (Edward A. Drew). To enable the algae to access sunlight, the jellyfish usually floats upside down in shallow water so that they can settle upside down on the sand bed, while providing sufficient sunlight to the algae. The algae also provide the jellyfish with oxygen in oxygen poor waters while photosynthesizing (David et al, 2009).

The algae benefits from this relationship as the jellyfish not only ensure the algae stays in a photic zone, it also provide protection with the numerous nematocysts in its tentacles. These nematocysts help the jellyfish not only in paralyzing the planktons and zoo plankton for food; it also stings any organism that tries to eat the algae, protecting the algae from its potential herbivores. The jellyfish also provide the algae with an abundance of carbon dioxide as it respires.

Since both organism benefits from this relationship while either is alive, it is a mutualistic relationship. However, so as long as either ones dies, the other will likely to be affected and leads to death eventually. With such a relationship ,  being upside-down isn’t that bad after all.

References:

1.  Upside-down jelly fish ,http://www.jellyfishfacts.net/upside-down-jellyfish.html

2.  A Symbiotic Lifestyle: C. xamachana and Zooxanthellae FINAL by Karla C. arcia. Http://jrscience.wcp.muohio.edu/fieldcourses05/PapersMarineEcologyArticles/ASymbioticLifestyle.C.xam.html

3.   Edward A. Drew, The biology and physiology of alga-invertebrate symbioses. I. Carbon fixation in Cassiopea sp. at aldabra atoll, J. exp. mar. Biol. EcoL, 1972, Vol. 9, pp. 65-69

4.  David T. Welsh , Ryan J. K. Dunn & Tarik Meziane, Oxygen and nutrient dynamics of the upside down jellyfish(Cassiopea sp.) and its influence on benthic nutrient exchanges and primary production, 2 February 2009

5.  Verde, E. A. & L. R. McCloskey. Production, respiration,and photophysiology of the mangrove jellyfish Cassiopea xamachana symbiotic with zooxanthellae: effect of jellyfish size and season. Marine Ecology ProgressSeries 168: 147–162, 1998

6. Picture 1 & 2 above are self taken on Pulau Semakua.

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Apr 14 2010

Spot the Difference~!

As I was walking down to the Bedok Reservoir Park in search of “inspirations” for this blog post, something else caught my eye. Are you able to spot the differences between these two bunches of Ixora?

Drastic differences between the colour of the Ixora inflorescence

Two Ixora inflorescence with different "colours"

Initially I was thinking, perhaps the weather was too hot. But, why does it only affect one part of the Ixora (right) while the part (left) is unaffected?

Discoloured Ixora Infected with Mealybugs

Ixora plant with discoloured flowers and infestation of mealybugs

Mealybugs on the Stem of the Ixora Plant

Mealybugs on the branch of the Ixora plant with discoloured flowers

Taking a closer look at the plant, it is actually being infected by the mealybug. Mealybugs are sexually dimorphic where the females are nymphal, flattened, soft and wingless while the males are winged. In this picture, the mealybugs present are most likely females. Another point to take note is that, the males have a much shorter lifespan and they do not feed at all (Novelguide.com, 2010) while the females feed on plant sap with their sucking mouthparts. The excess feeding on the sap may have led to insufficient water and nutrients being transported to the flowers and leaves, which may cause wilting or even death of the plant (Lindquist, 1997). This may account for the distinct decolouration of the Ixora flowers and the absence of leaves on the stem itself.

This nest was found on another Ixora plant within the vicinity of the discoloured Ixora inflorescence

This nest was found on another Ixora plant within the vicinity of the discoloured Ixora inflorescence

Within the distance of less than 1m lies the nest of the weaver ants. These ants have a symbiotic relationship with the mealybugs where the mealybugs secrete honeydew, a sweet carbohydrate secretion for the ant’s consumption (Lindquist, 1997). In return, the ants provide them with protection (Tan, Chou, Yeo, Ng, 2007), leading to massive proliferation and infestion of the mealybugs. Perhaps this is the reason for the increased number of decolourised Ixora along that stretch of pathway.

References:

Hemiptera, 2010. Retrieved from http://www.novelguide.com/a/discover/grze_03/grze_03_00199.html (accessed on 13/04/2010)

Lindquist, R., 1997. Mealybugs. Retrieved from http://floriculture.osu.edu/archive/oct97/mealybug.html (accessed on 13/04/2010)

Tan, T.W., Chou, L. M., Yeo, C. J., Ng, K. L., 2007, The Natural Heritage of Singapore, second edition (p. 154).  Singapore: Prentice Hall

Second Source:

A Review of the Association of Ants with Mealybug Wilt Disease of Pineapple

https://scholarspace.manoa.hawaii.edu/bitstream/10125/95/1/36_9-28.pdf

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Apr 14 2010

Stealing from the huge golden webs!

Published by under species interactions

Look under the overhead bridges the next time you walk along Bukit Timah road and you would be surprised to find an extremely huge web made by the Batik Golden Web Spider, Nephila antipodiana. I chanced upon this web two weeks ago and I realised that besides it being golden in colour, the web was also extremely hardy and does not break easily like those commonly encountered ones. As its name implies, the spider gets its name from the golden colour of its silk. This is how it looks like.

Batik golden web spider

“Batik golden web spider” by Ron Yeo. Taken at Sungei Buloh on 14 March 2010

Although these spiders are not the largest in size, they actually make the largest and strongest web and can run from the top of a tree at a size of up to 6m high and 2m wide. Due to its durability, these webs can last several years instead of being dismantled often. In fact, the silk is almost as strong as Kevlar, the strongest man-made material (Tan, 2001).

Although having this huge and strong web means an unlimited buffet for the spider since more prey can be caught, it does come with its perils. Often, trapped insects too small to eat would be left on the webs to decay, hence spoiling the web. As a result of this, the web becomes host to numerous Red silver spiders, Argyrodes flavescens. Note the three other smaller spiders in red circles on the web, besides the Batik golden web spider from this photo below.

Three red silver spiders and a Batik golden web spider

“Three Red silver spiders and a Batik golden web spider” by spiderman (Frank). Taken at Queestown on 22 February 2008.

These A. flavescens pick on the leftover insects trapped in the web of the host, or prey stored by the host in the web, or even a freshly killed victim that is being consumed by the host (Koh, 2000). This thieving is known as a kleptoparasitic relationship. It occurs when an organism gets its food by scavenging or stealing from another organism (Amateur Entomologists’ Society, 2010).

Due to this relationship, N. antipodiana suffers since its food source is depleted, leading to frequent web relocations (Rypstra, 1981). Hence, this brings to mind the question of whether the Batik golden web spider would still face as severe a problem if it chooses to weave smaller webs instead, thus allowing it to guard its prey better.

References

Golden Orb Web Spider by Ria Tan, 2001.  Mangrove and wetland wildlife at Sungei Buloh Nature Park. URL: http://www.naturia.per.sg/buloh/inverts/nephila.htm (Accessed on 14th April, 2010)

Red Silver Spiders by Joseph Koh  K. H, 2000. A guide to Common Singapore Spiders. URL: http://habitatnews.nus.edu.sg/guidebooks/spiders/text/Argyrodes_flavescens.htm (Accessed on 14th April, 2010)

Definition of Kleptoparasite by Amateur Entomologists’ Society (2010). URL: http://www.amentsoc.org/insects/glossary/terms/kleptoparasite (Accessed on 14th April, 2010)

Ann L. Rypstra. (1981). The Effect of Kleptoparasitism on Prey Consumption and Web Relocation in a Peruvian Population of the Spider Nephila clavipes. Oikos, 37, pp. 179-182.

Grostal, P., Walter, D.E. (1997). Kleptoparasites or commensals? Effects of Argyrodes antipodianus (Araneae: Theridiidae) on Nephila plumipes (Araneae: Tetragnathidae). Oecologia,111, pp. 570-574.

Koh, T.H. & Li, D. (2002). Population characteristics of a kleptoparasitic spider Argyrodes flavescens (Araneae: Theridiidae) and its impact on a host spider Nephila pilipes (Araneae: Tetragnathidae) from Singapore. The Raffles Bulletin of Zoology, 50(1), pp. 153-160.

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Apr 14 2010

Cassiopea spp. and the case of undersea mutualism.

Published by under species interactions

Cassiopea sp., photographed personally from the shores of Pulau Semakau, Singapore.

Cassiopea sp., photographed personally on 27 Feb 2010 from the shores of Pulau Semakau, Singapore.

Sea anemone? Soft coral? A dead jellyfish? An upside-down jellyfish?

If your guess was the latter, you would be right.

Cassiopea is a genus of jellyfish that live their lives standing on their heads. Why would they do that?

Cassiopea spp. house thousands of photosynthetic zooxanthallae within their mesoglea (Berryman, n.d.). Zooxanthallae provide carbon for the jellyfish, and in return, the jellyfish provide the zooxanthallae with minerals, shelter (Tan, 2009) and presumably protection. Cassiopea spp. therefore live upside-down to allow their zooxanthallae companions access to sunlight. Also for this reason, Cassiopea spp. are found mainly in shallow marine waters – for example in the seagrass meadows of our very own Pulau Semakau (Tan, 2009).

The symbiotic relationship between Cassiopea jellyfish and zooxanthallae is not dissimilar to the one between zooxanthallae and corals. Unlike with the corals however, the zooxanthallae do not provide for all of the carbon required by the jellyfish. Instead of being able to wait for food to be put on their figurative tables, the jellies do actually still need to feed themselves to an extent (Vodenichar, 1995), either through filter feeding, absorption of nutrients from the water, or by capturing prey with their nematocysts (Berryman, n.d.).

Upside-down jellyfish do not stay put on the seafloor all of the time though! If disturbed, a swarm of upside-down jellyfish can launch upwards (Maui Ocean Center, n.d.).

Cassiopea sp. swimming upright, photographed personally from the shores of Pulau Semakau, Singapore.

Cassiopea sp. swimming upright, photographed personally, on 28 Mar 2010, from the shores of Pulau Semakau, Singapore.

Under normal circumstances however, these jellyfish prefer to be upside-down, and if you try to flip them over, they will slowly turn themselves upside-down again (Tan, 2009)!

Cassiopea sp. turning itself ‘the right way up’, photographed personally from the shores of Pulau Semakau, Singapore.

Cassiopea sp. turning itself ‘the right way up’, photographed personally, on 28 Mar 2010, from the shores of Pulau Semakau, Singapore.

But wait! There is a third party in this relationship…

Sometimes, Cassiopea spp. may be carried on the backs of urchin crabs (Dorippe frascone) for defense against their predators.

Dorippe frascone carrying Cassiopeia andromeda on its back. Photo credit to: http://www.starfish.ch/c-invertebrates/hydroids.html#Cassiopeidae

Dorippe frascone carrying Cassiopeia andromeda on its back. Photo adapted from a photo copyrighted to Teresa Zubi at URL: http://www.starfish.ch/c-invertebrates/hydroids.html#Cassiopeidae

It seems like it’s mutualism with a dash of an exploitative interaction thrown into the mix, here.

Which makes the ecological interactions in Nature all the more fascinating.

References:

Second source: Holland, B. S., et al., 2004. Global phylogeography of Cassiopea (Scyphozoa: Rhizostomeae): molecular evidence for cryptic species and multiple invasions of the Hawaiian Islands. Marine Biology, 145(6): 1119-1128.

“Upside-down Jellyfish,” by Matt Berryman. Marine Invertebrates of Bermuda, n.d.. URL: http://www.thecephalopodpage.org/MarineInvertebrateZoology/Cassiopeaxamachana.html (accessed on 14 April 2010).

“Upside-down Jellyfish,” Maui Ocean Center Marine Life Profile. Maui Ocean Center, The Hawaiian Aquarium, n.d. URL: http://www.mauioceancenter.com/marinepdf/upside-down_jellyfish.pdf (accessed on 14 April 2010).

“Upsidedown jellyfish,” by Ria Tan. Wild Factsheets, March 2009. URL: http://www.wildsingapore.com/wildfacts/cnidaria/others/jellyfish/upsidedown.htm (accessed on 14 April 2010).

Vodenichar, J.S., 1995. Ecological physiology of the scyphozoan Cassiopea xamachana. M.S. Thesis, University of Georgia, Athens, USA. 

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Apr 14 2010

Giant Forest Ants (Camponotus gigas) and their ‘bloody fight’

Published by under species interactions

One would never thought of ants getting into “bloody fights”. However, that’s exactly what the giant forest ants (Camponotus gigas) do in order to protect their territory. Found in Bukit Timah and the Central Catchment Nature Reserves (lekowala 2005), giant forest ants are distinctive black and reddish brown ants which can reach lengths of 30mm. They are primarily nocturnal (Pfeiffer & Linsenmair 1999), coming out of their nest to forage through the night. There are two forms of this species, namely the smaller minor workers and the larger major workers.

These larger major workers exhibit territorial behavior (interference competition mechanism) and are involve in both inter-specific competition as well as intra-specific competition. Their territorial behavior was evident in their nesting patterns, which are connected by trails through the forest canopy (Pfeiffer & Linsenmair 1999).

Giant Forest Ants (courtesy of Ria Tan, retrieved from http://www.wildsingapore.com/riablog/photos/040818cnr/photos/photo_12.html)

Giant Forest Ants (courtesy of Ria Tan, retrieved from http://www.wildsingapore.com/riablog/photos/040818cnr/photos/photo_12.html)

Inter-specific conflicts with sympatric Camponotus species always led to violent, “bloody” fights of all castes. It began with mass recruitment of workers, followed by violent fights, causing mass deaths. Besides using their mandible, they also sprayed acid and used their poison gland (Pfeiffer & Linsenmair 2001).

In contrast, intra-specific competition takes on a gentler approach known as ritual fights (Pfeiffer & Linsenmair 2001)(Fig. 1.), with a few specialist major meeting at fixed tournament places. They generally use their mandible for fighting. Usually, the fights would last the whole night (Pfeiffer & Linsenmair 1999). Surprisingly, ritual fights were a means that had evolved to minimize loss of “combats” as territorial competition can result in massive loss of workers on both sides. Interestingly, these fights can last for several months (Pfeiffer & Linsenmair 2001)!

References:

Camponotus gigas and the “art of war,” by lekowala. The Biology Refugia, 8 June 2005. URL: http://staff.science.nus.edu.sg/~sivasothi/biorefugia/archive/2005_06_01_archive.html (assessed on 7 April 2010).

Pfeiffer M. & Linsenmair K.E. (2001). Territoriality in the Malaysian giant ant Camponotus gigas (Hymenoptera/Formicidae). Japan Ethological Society and Springer, 19:75–85

Pfeiffer M. & Linsenmair K.E. (1999). Contributions to the life history of the Malaysian giant ant Camponotus gigas (Hymenoptera, Formicidae). Insectes soc, 47 (2000) 123–132

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Apr 14 2010

Mummy, Why did you eat daddy alive?

Published by under species interactions

A few days back, while walking home, I accidentally kicked something on the floor. After shining my handphone light, I saw a Praying mantis ferociously flashing it’s spiked forelegs at me.

Hierodula paellifera, Taken from http://commons.wikimedia.org/wiki/File:Hierodula_patellifera.jpg.

Hierodula patellifera, Taken from http://commons.wikimedia.org/wiki/File:Hierodula_patellifera.jpg. (Accessed on 14 April 2010).

Praying mantises are predatory and carnivorous insects that belong to the family Mantidae. Majority of mantises are ambush predators. Their camouflage abilities, patience, speed and spiked forelegs give them an added advantage over their unexpecting prey. Praying mantises also display interesting mating behaviours that are still being researched today.

Hierodula patellifera is one of the many species found in Singapore’s secondary forests, scrubland, gardens and parks. It was discovered that virgin female Hierodula patellifera would initiate mating by adopting a characteristic posture with abdominal pulsations, accompanied by the simultaneous release of pheromones to attract males in the vicinity (Leong, 2009).

Sexual cannibalism is evident in many mantis species. During mating, the female which is physically more powerful, seizes the male and commences to eat the head and thorax. The male, even without a head, manages to clamber onto the back of the female and successfully copulate with her, remaining attached to her for several hours while it still showed signs of life (Roeder, 1935). This highlighted that the male is able to copulate while being eaten alive by the female.

Mantis religiosa couple mating, Taken from http://en.wikipedia.org/wiki/File:Mantis_religiosa_couple.JPG.

Mantis religiosa couple mating, Taken from http://en.wikipedia.org/wiki/File:Mantis_religiosa_couple.JPG. (Accessed on 14 April 2010).

Under a low diet regime, the female that ate their mating partner produced significantly heavier oothecae than those that were not allowed to. Therefore the female’s nutritional state influenced her likelihood of eating the male. These results confirm that male and female fecundity can be increased by sexual cannibalism. However, observations indicate that males do not sacrifice themselves at mating, but attempts to avoid being eaten, suggesting that while sexual cannibalism may be adaptive for females, it is unlikely to be so for males (Birkhead et al, 1988).

Praying Mantis Sexual Cannibalism, Taken from http://commons.wikimedia.org/wiki/File:Praying_Mantis_Sexual_Cannibalism_European-37.jpg.

Praying Mantis Sexual Cannibalism, Taken from http://commons.wikimedia.org/wiki/File:Praying_Mantis_Sexual_Cannibalism_European-37.jpg. (Accessed on 14 April 2010).

References

-Roeder K. D (1935). An experimental analysis of the sexual behavior of the praying mantis (Mantis religiosa L.). Biological Bulletin, Marine Biological Laboratory.

-Birkhead T.R, K. E. Lee and P. Young (1988). Sexual Cannibalism in the praying mantis Hierodula Membranacea. BRILL. Behaviour, Vol. 106: 112-118.

-T.M. Leong (2009). Oviposition and Hatching in the Praying Mantis Hierodula Patellifera (Serville) in Singapore (Mantodea: Mantidae: Paramantinae). Nature In Singapore 2009, Vol. 2: 55-61.

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Apr 14 2010

Our Household’s Pest Controller, Who would have thought?

Published by under species interactions

Prey is captured by Gecko

Figure 3: Prey is captured by Gecko. Picture adapted from Asian Geckos and Wasps 2004. URL: http://www.qnc.org.au/Papers/Gecko/Gecko.html (Assessed on 14 April 2010).

Lizards! To most that are not fans of these nocturnal, cold blooded reptiles that we usually see on ceilings, walls, the slightest thought of them might just take away one’s appetite (Bustard,1970). Nevertheless, lizards might just be the solution to a more environmental elimination of some household pests such as flies and insects within one’s home.

Indeed, there are many species of lizards found in different parts of the world with different characteristics which enable them to survive in their habitat. There are couple of lizard species in Singapore of which one of the commonest native gecko sighted within our household is the urban house gecko, Hemidactylus Frenatus (Lim et al., 1992). Although there are lizards which are more aggressive than others, fret not, Hemidactylus Frenatus are considerably harmless (Lim et al., 1992).

Hemidactylus Frenatus are usually seen near lighted areas, ready to pounce on any unsuspecting unguarded prey, usually winged insects (Mahendra,1936). The idiom ‘Silence before the storm’ would probably give one a rough idea of how the geckos prey on their prey. Once a prey is spotted usually via their movements, the gecko hastens to the spot and slows down upon nearing the prey. Then, it waits for the perfect moment before it sets upon a silent kill. Preys are usually swallowed alive (Mahendra, 1936).

Agility, skill and precision are all it takes for Hemidactylus Frenatus to eliminate pests such as flies and mosquitoes which usually take much longer and double luck for man to achieve via physical means.  The gecko’s way of predation, that might explain why senses of sight, smell, and hearing with greater importance on sense of sight of lizards, play important roles in their predation (Chou et al., 1988). In the campaign towards a greener society coupled with the gecko’s expertise, house geckos such as Hemidactylus Frenatus as a means to reduce household pests might not be a bad idea!

Gecko notices wasp’s nest.

Figure 1: Gecko notices wasp’s nest. Picture adapted from Asian Geckos and Wasps 2004. URL: http://www.qnc.org.au/Papers/Gecko/Gecko.html (Assessed on 14 April 2010).

Gecko got very close the wasp’s nest and did not move even when wasp’s wing brushes its nose.

Figure 2: Gecko got very close the wasp’s nest and did not move even when wasp’s wing brushes its nose. Picture adapted from Asian Geckos and Wasps 2004. URL: http://www.qnc.org.au/Papers/Gecko/Gecko.html (Assessed on 14 April 2010).

References

Bustard, H. R.(1970). Activity Cycle of the Tropical House Gecko, Hemidactylus frenatus. Copeia, 1970(1):173-176,

Chou, L. M., Leong, C. F. and Choo, B. L. (1988). The Role of Optic, Auditory and Olfactory Senses in Prey Hunting by Two Species of Geckos. Journal of Herpetology, 22(3) :349-351.

Lim, K.K.P. and Lim, F.L.K. (1992). A Guide to the Amphibians and Reptiles of Singapore. Singapore: Singapore Science Centre.

Mahendra, B.C. (1936). Contributions to the Bionomics, Anatomy, Reproduction and Development of the Indian House-Gecko, Hemidactylus Flaviviridis Ruppel. Part 1. Proceedings: Plant Sciences, 4(3): 250-281.

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Apr 14 2010

The Mutual Affair

Published by under species interactions

Have you ever noticed and wondered why Coral Reefs out skirting the southern islands of Singapore appear to be in various colours?

 This is due to the presence of Mutualistic Relationship between the Reef-building hard corals (Order Scleractinia) and the Zooxanthellae, Symbiodinium spp. These microscopic single cell algae live within the corals’ polyp tissues and are responsible for its colourations (WildSingapore, 2008).

 

Picture 1: Zooxanthellae living within coral found in Pulau Hantu in 2005

Picture 1: Zooxanthellae living within coral found in Pulau Hantu in 2005

 

These marine species are metabolically interdependent and both benefits from the symbiosis.

Corals have the inability to generate sufficient foods for survival (Megan, 2009).  By having zooxanthellae living in its cell tissues, these photosynthetic algae help to make foods for the corals polyps. The carbohydrates made are used by the polyp as nutrient for growth (e.g. to build their calcium carbonate skeletons) and the oxygen for respiration. Carbon dioxide in return cycled back to the zooxanthellae. In the process, carbon dioxide are removed. This is important for polyp calcification under optimum conditions, thus accounting for the many coral reefs observed in Singapore.

Also, nitrogen and phosphorus are cycled. Zooxanthellae take in ammonia as nutrient given off as waste by the polyp, and return amino acids back for its growth (Megan,2009). This thus provides a nutrient rich environment for excellent growth for both.

 

However, this mutualism can be upset by environmental stresses.

Unusually warm or cool water temperatures, a change in salinity or excessive exposure to sunlight or shading or human activities (e.g. sedimentation or land reclamation) can lead to expulsion of the zooxanthellae by the corals (WildSingapore, 2008). This is known as Coral Bleaching.

 

Coral bleaching found on the Pulau Hantu in July 2007

Picture 2: Coral bleaching found on the Pulau Hantu in July 2007 (Photo reference: 070701hntd2943 )

 

When this happens, this poses serious threat to Singapore reefs as this may lead to coral death unless another algal mutualism can be re-established.  This thus in turns affect the marine ecosystem as coral reefs support the survival of many marine organisms . One example is the 1998 Coral bleaching event, affecting 50-90% of the reef organisms (Reef Ecology Study Team, NUS, n.d). URL: http://coralreef.nus.edu.sg/

 

It is thus strongly believed that more should be done to protect these Coral Reefs in Singapore, both fiscal and public. Corals have already many a time experience threats, losing their “beautiful” colouration and some even die locally. Are you ready to let this happen again and bear the consequences of the possible complete extinction?

 

 

 References

Second source link: Reef Corals: Mutualistic Symbioses Adapted to Nutrient-Poor Environments, by L. Muscatine and James W. Porter © 1977 American Institute of Biological Sciences. URL: http://www.jstor.org/pss/1297526. (Accessed on 10th April 2010)

“Hard Corals and coral reefs” by Wildfactsheets. WildSingapore, October 2008. URL: http://www.wildsingapore.com/wildfacts/cnidaria/coralhard/coralhard.htm (Accessed on 10th April 2010)

“Symbiotic Relationship between Coral and Algae-corals and zooxanthellae need each other to survive” by Megan. J, 20th May 2009. URL:http://marine-life.suite101.com/article.cfm/the_symbiotic_relationship_between_coral_and_alg (Accessed on 10th April 2010)

“Coral Reefs of Singapore” by Reef Ecology Study Team, National University of Singapore, n.d. URL: http://coralreef.nus.edu.sg/ (Accessed on 10th April 2010)

“Pulau Hantu-A celebration of marine life: Silts starving Hantu’s reefs” by Debby. Hantu Blog by Habitatnews, 24 March 2005. URL: http://habitatnews.nus.edu.sg/news/pulauhantu/2005/03/silt-starving-hantus-reefs.html (Accessed on 10th April 2010)

“Coral bleaching” by Ria Tan, WildSingapore. Flickr from yahoo channel, 12 July 2009. Photo reference: 070701hntd2943. URL: http://www.flickr.com/photos/wildsingapore/3712796216/ (Accessed on10th April 2010)

 

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Apr 14 2010

Itsy Bitsy Stealer

 
Nephila spider with smaller marked in squares.
Nephila spider with smaller Argyrodes spiders marked in squares. (Frank’s Photo Essays, 2007)

While on a camping trip on Pulau Ubin, a spider web with a Nephila at its center, similar to the one in the picture above, was spotted. Upon a closer look, there were also five smaller spiders which i initially thought to be red ants. Further research on the world wide web (no pun intended), made me realise that these smaller spiders, with long, thin black legs and shiny red-brown, domed abdomen with white spots, were of the species Argyrodes flavescens or commonly known as the Red Silver Spiders (picture below). The species is one of the more than 310 species of spiders recorded in Singapore (Song, Zhang & Li, 2002).

Red Silver Spider (Argyrodes flavescens)

Red Silver Spider, Argyrodes flavescens (Frank's Photo Essays, 2007)

Argyrodes flavescens, is a species of spider belonging to the Theridiidae family. It is very small with a body length of about 3 mm and is widely distributed in Southeast Asia. Like other members of this genus, this species is a kleptoparasite, feeding off a host spiders’s prey and living on the host’s web even though they can spin their own webs (Koh, 2000). The larger webs tend to attract more kleptoparasites than the smaller ones.

These “food stealers” usually occupy the webs of nephilids, feeding on insects trapped or prey stored by the hosts’s web and even on prey that is being consumed by the host. The host seems to be not perturbed by their presence, probably because the small size of the Red Silver Spiders. The kleptoparasite benefits by either obtaining prey or other objects that it itself could not attain, or by saving the energy and time required to obtain it. However, since the Red Silver Spider can feed on small trapped insects that are not eaten by the host, the relationship can sometimes be commensal or even mutual (Koh & Li, 2002).

I guess not every spider fights crime.

Hard to imagine him getting caught for such a 'crime'.

Hard to imagine him getting caught for such a 'crime'. (Scott Kinmartin's Photo Stream, 2008)

   

 References

D. X. Song, J. X. Zhang & Daiqin Li (2002) Checklist of spiders from Singapore (Arachnida: Araneae) The Raffles Bulletin of Zoology 50(2): 359-388. 

Joseph K. H. Koh (2000) A Guide to Common Singapore Spiders, BP Guide to Nature Series published by the Singapore Science Centre and sponsored by British Petroleum.

Koh, T.H. & Li, D. (2002). Population characteristics of a kleptoparasitic spider Argyrodes flavescens(Araenae: Theridiidae) and its impact on a host spider Nephila pilipes(Araneae: Tetragnathidae) from Singapore. The Raffles Bulletin of Zoology 50(1):153-160.

” Adventures with curiosity and learning,” by Frank Starmer. Frank’s photo essays . URL: http://frank.itlab.us/photo_essays/wrapper.php?may_05_2007_queenstown.html (accessed on 06 Apr 2010)

“Spiderman”  by Scott Kinmartin. Scott Kinmartin’s Photostream URL: http://www.flickr.com/photos/scottkinmartin/2449092539/ (accessed on 06 Apr 2010)

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Apr 14 2010

Nepenthes Pitcher- A Death Trap for all Arthropods?

Published by under plants,species interactions

 
Geosesarma perracae in pitcher plant
Geosesarma perracae in pitcher plant

(Photograph from Ivan Kwan’s blog; Tan & Ng, 2008)

  Nepenthes are tropical pitcher plants native to Singapore (Bugs & Buds, 2001). Although they are able to photosynthesize and can produce flowers, fruits and seeds, these plants are carnivorous plants that grow in mineral-deficient soils and feed on arthropods (Myers, 2001) such as the cockroach cf. Ectobius (Hollinger) as the plants are adapted to get extra nutrients from their prey (Bugs & Buds, 2001).

 Arthropods consist of a diverse group of organisms (Myers, 2001). Not all arthropods are digested by these plants when they enter the pitcher (Tan & Ng, 2008). Some are able to enter the pitcher and foray in it without getting killed (Tan & Ng, 2008). In the photograph above, a species of crab scientifically known as Geosesarma perracae was seen foraying inside a pitcher of Nepenthes ampullaria for remains of prey at the Sime Road swamp forest, west of MacRitchie Reservoir at the Central Nature Catchment Nature Reserve (CCNR) in Singapore (Tan & Ng, 2008).

 In fact, arthropod communities such as those consisting mainly of aquatic dipteran larvae have been found living in Nepenthes pitchers (Mogi & Yong, 1992). They feed on the remains of prey helping in digestion as the slow action of enzymes secreted by Nepenthes pitchers could result in the prey decomposing and leading to growth of bacteria and fungi that could harm the plant (Kwan). This shows mutualistic relationships existing between Nepenthes pitchers and certain arthropods.

 The Nepenthes pitchers thus can have mutualistic relationships with certain arthropods and these arthropods will not be killed but for others; it is a death trap where one step into the pitcher will lead to a slippery slide to doom.

 References:

Bugs & Buds. (2001). The Nepenthes in Singapore. Retrieved April 5, 2010 from http://bugsnbuds.com/Singapore-Nepenthes.php.

Hollinger, R. S. Nepenthes macfarlanei: Prey found in ground pitchers. Carnivorous Plant Newsletter, pp. 46-50

Kwan, I. Meet the carnivorous pitcher plant. Retrieved April 5, 2010 from http://lazy-lizard-tales.blogspot.com/2009/06/meet-carnivorous-pitcher-plant.html.

“Meet the carnivorous pitcher plant,” by Kwan, I. The Lazy lizard’s tales, 28 June, 2009. URL: http://lazy-lizard-tales.blogspot.com/2009/06/meet-carnivorous-pitcher-plant.html. (accessed on 5 April, 2010)

Myers, P. (2001). “Arthropoda” (On-line), Animal Diversity Web. Retrieved April 5, 2010 from http://animaldiversity.ummz.umich.edu/site/accounts/information/Arthropoda.html.

Mogi, M., & Yong, H. S. (1992). Aquatic arthropod communities in Nepenthes pitchers: the role of niche differentiation, aggregation, predation and competition in community organization. Oecologia, 90: 172-184.

Tan, H. H., & Ng, P. K. L. (2008). First record in Singapore of a Nepenthiphilous crab, Geosesarma perracae (Crustacea: Decapoda Sesarmidae). Nature in Singapore, 1: 201-205.

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Apr 14 2010

White & Fluffy, Sweet but Deadly?

A few weeks ago, I was surprised to find that my Watermelon Begonia, Pellonia repens, had some white clumpy patches growing on the underside of its leaves. It looked quite disgusting, and I thought it was a fungal infection.

Cottony lumps under leaves

So I posted some pictures of them on Facebook, and my friend said it may be mealybugs. Curious, I searched for more information. Mealybugs (Family Margarodidae) are unarmoured scale insects that produce fine powdery wax in long lateral filaments on its body surface (Cox & Pearce, 1983). They are common crop pests that are usually found in dense colonies. The wingless females use sucking mouthparts to feed on plant sap while males don’t feed. As mealybugs have little or no mobility, the newly hatched nymphs are dispersed by winds (Lim, Murphy, Morgany, Sivasothi, Peter K. L. Ng, Soong, Tan, Tan & Tan, 2001).

I wasn’t sure if they were really bugs and not fungus, but these “things” didn’t seem healthy for the plant. Removal of them with tissue paper produced a yellowish stain, perhaps in the vein of this sentence from Succulent-Plant: “A squashed mealy bug often leaves a characteristic red stain: the cochineal insect, from which a food colourant is made, is a type of mealy bug.”

Stains after removal from the plant.

Mealybugs are considered as a parasite for most plants, but for some they may be beneficial as they function as extrafloral nectaries due to their honeydew secretions. These would attract ant colonies that protect the plant from herbivores. Likewise, the mealybugs are protected from predators too as the ants tend the mealybugs for their sweet honeydew secretion (Rico-Gray & Thien, 1989). Not unlike humans and their cows, you could say!

Ants farm mealybugs for their honeydew!

A point of interest would be mealybugs are both parasites and mutualists, and I guess not many organisms can claim that title!

References:

Cox JM, Pearce MJ. 1983. Wax produced by dermal pores in three species of mealybug (Homoptera : Pseudococcidae). International Journal of Insect Morphology and Embryology 12: 235-248.

Lim KKP, Murphy DH, Morgany T, Sivasothi N, Peter K. L. Ng, Soong BC, Tan HTW, Tan KS, Tan TK. 2001. Volume 1: The Ecosystem and Plant Diversity and Volume 2: Animal Diversity. In: Ng PKL and Sivasothi N, eds. A Guide to Mangroves of Singapore. Singapore: Singapore Science Centre.

Rico-Gray V, Thien LB. 1989. Ant-Mealybug Interaction Decreases Reproductive Fitness of Schomburgkia tibicinis (Orchidaceae) in Mexico. Journal of Tropical Ecology 5: 109-112.

“mealybug.”, by The Columbia Encyclopedia, Sixth Edition. 2008. URL: http://www.encyclopedia.com/doc/1E1-mealybug.html (Accessed Apr 14 2010).

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