Fig Tree and Fig Wasp = Babysitter and Matchmaker

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.





  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: (accessed on 15 Apr 2010)
  5. “Bukit Timah Nature Reseve- a precious remnant of primary rainforest” by Nick Baker. Ecology Asia, 2010. URL: (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

What Are “Hens” Doing Near The Lake?

Second Swan Lake of Botanic Gardens

Second Swan Lake of Botanic Gardens

During one of my recent visits to the Singapore Botanic Gardens on 14th April 2010, I was strolling across the bridge located at the second swan lake, when I spotted a few White- Breasted Waterhens (Amaurornis phoenicurus) in this vicinity. Some were in shallow regions (<20cm) of the lake and a few on open grass patches. However, they were more commonly found at regions around the lake with denser vegetations growth such as Pandanas sp. and Cyprus sp.
White- Breasted Waterhen (Amaurornis phoenicurus) in front of Pandanas sp.

White- Breasted Waterhen (Amaurornis phoenicurus) in front of Pandanas sp.

Pandanas sp

Pandanas sp

The dense cluster of vegetation provides shade and refuge (Chia. A, 1999) for the bird, while the bird’s defecation increases the fertility of the soil for better plant growth. A mutualistic interaction is therefore present between them.
The shallow waters where the White- Breasted Waterhen fed and the bridge across part of the lake

The shallow waters where the White- Breasted Waterhen fed and the bridge across part of the lake.

There is also interaction between the waterhen and its environment. The availability of grains and worms in the grass, together with insects (Chia. A, 1999) such as pondskaters in the lake attracts both native and migrant waterhens from the north to this area. (Strange. M, 2000) In turn, the very presence of the waterhen adds diversity to the environment.

White Breasted Waterhen on a grass patch

White Breasted Waterhen on a grass patch

Just as how humans converse with one another in a variety of languages, Waterhens are no exception. I chanced upon a three birds communicating with one another through “hoo- hooking” noises. At one time, only one would be “hooing” at a constant slow tempo, while the other responses after awhile. Yet at other times, the entire group would “hoo” together continuously. Naturalist writer, Eha describes their call as “ Beginning with loud harsh roars… then suddenly changing to … the coo of a dove.” (Hugh. W, 1998). These noises are unique to them and allow them to interact with one another successfully without letting other organisms know what they are up to.

Visible through the dense undergrowth of ferns and Metroxylon sagu

Visible through the dense undergrowth of ferns and Metroxylon sagu

These birds are pretty sensitive creatures. Noticing any slight movement made by me, they would quickly turn their backs and ran into the dense undergrowth. Even when a sudden breeze came, they froze in their current activity and one or two from the group retreated into the bushes. However, if one remains motionless, after a short while, it will reappear from its hide out and resume its perky strut. (Chia. A, 1999)


Spotting these spots

Symbiotic associations between some shrimps and sea anemones are common in the tropics (Bruce, 1976). The Five-spot anemone shrimp (Periclimenes brevicarpalis) is one such example.


This adorable little shrimp is about 4cm long and known as the Five-spot anemone shrimp because of its 5 unique spots found on its tail which are black with an orange centre. Large conspicuous white spots are observed on its almost transparent body and at the base of its caudal fin. The pincers and legs are distinctively marked with purple bars.

Five-spot anemone shrimp on a Magnificent anemone

Five-spot anemone shrimp in a magnificent anemone 

They are usually found in pairs (a male and a female) in anemones like Giant carpet anemone (Stichodactyla gigantea), Haddon’s carpet anemones (Stichodactyla haddoni) and Magnificent anemone (Heteractis magnifica).


Though little is known about the mechanisms protecting crustaceans that can come into contact with the tentacles of sea anemones without being stung (Writz, 1997). Shrimps were observed to rest on the host column where mucus secretions were evident (Fautin, 1995). Probablysimilar to anemonefishes, the shrimps coats themselves with mucus secreted by the anemone thus prevent them from being stung by the tentacles. The shrimps tend to hide from the anemone when molting as it loses its mucus coating.


The shrimps seek protection in anemones and scavenging on ‘leftovers’. However, anemones do not seem to benefit from this symbiosis and may even be harmed. It was reported that P. Brevicarpalis due to starvation, may resort to tearing the tentacles of anemones and eating it (Fautin et al., 1995). However, under normal circumstances, the shrimps do not exhibit such behaviour.


This Five-spot anemone shrimp also showed various interesting interactions with other marine organisms. More interestingly, other Periclimenes sp. was observed to provide ‘cleaning services’ to some fishes. Perhaps further research on P. Brevicarpalis could be done to determine if there is a mutual relationship between them.



 1. Five-spot anemone shrimp on Wild Factsheets by Ria Tan (Accessed on 14th April 2010)

 2. Fautin D.G., Guo C.C., Hwang J.S., 1995, Costs and benefits of the svmbiosis between the anemoneshrimp Periclimenes brevicarpalis and its host Entacmaea quadricolor, Marine Ecology Progress Series, Vol. 129, pp. 77-84

 3. Bruce, A.J., 1976, Shrimps and prawns of coral reefs, with special reference to commensalism. Biology and geology of coral reefs, Vol. 3, Biology 2, edited by O.A. Jones and R. Endean, Academic Press, New York, pp. 37-94

 4. Wirtz P., 1997, Crustacean symbionts of the sea anemone Telmatactis cricoides at Madeira and the Canary Islands* J. Zool., Lond., Vol. 242, pp. 799-811

5. Spotte S., 1998, “Cleaner” Shrimps?, Helgolander Meeresuntersuchungen, Vol. 52, pp. 59-64

Going my way? Blood sucking hitch-hikers!

I came across this photo taken by Horace Tan while blog-surfing recently and at first glance mistook the bright red object for the butterfly’s eye. Upon closer inspection of both the photo and the site itself, I realized that it is in actual fact, a mite!

‘What in the name of ecology is a mite doing ‘impersonating’ the butterfly’s eye?’ you might ask?

Truth is, this brightly-coloured mite clings onto the butterfly and feeds on its blood! At the same time, the mite uses the butterfly as a private transport, dropping off when it is full from feeding. Phoresy, a dispersal method, is where an organism attaches itself to another for merely transportation only (Encyclopaedia Britannica Online, 2010). However, in this case, since the mite is mainly feeding on the butterfly’s blood, this is more of parasitism coupled with phoresy.

Mites, from the subclass Acari, are one of Nature’s most successful and diverse groups of invertebrate, with over 45,000 species documented (David Evans Walter et al, 1996).  They can cause allergic diseases in humans and among them, the House dust mite, Dermatophagoides pteronyssinus, is one of the most common mites to cause allergic reactions (Teoh, 1977). This particular mite in the photo is suspected to be Trombidium breei from the family Trombidiidae (Ben Bolet, 2009). Interestingly, it is unclear why the mites are mostly observed attached to the butterfly’s head or eye instead of the thorax.

Bright red Trombidium mite (from Ben Bolet, 2009)

Bright red Trombidium mite (from Ben Bolet, 2009)

Even though these mites feed on the butterfly’s blood, the amount taken is apparently so little that it appears to be harmless to the host butterfly! Studies have shown that these mites do not in any way affect the butterfly in its flying or behavior; those with mites behave the same as those without (Conradt et al, 2002). This relationship also does not shorten the butterfly’s lifespan or reproductive capabilities, thus the butterflies do not seem to mind it one bit. Talk about having a free lunch!


1. Second Source Link: Conradt, L., S.A. Corbet, T. J. Roper & E.J. Bodsworth, 2002. Parasitism by the mite Trombidium breei on four U.K. butterfly species. Ecological Entomology, 27 (6): 651-659.

2. “Parasitic Mites on Butterflies” by Khew SK. Butterflies of Singapore, 21 October 2009. URL: (accessed on 7 April 2010)

3. “Trombidium, Dicrocheles mites and their Lepidoptera hosts” by Ben Bolet. Ben The Butterfly Guy, 23 October 2009. URL: (accessed on 7 April 2010)

4. “Phoresy.” by Encyclopaedia Britannica Online, 2010. URL: (accessed 8 April 2010)

5. “Acari” by David Ethans Walter, Gerald Krantz, and Evert Lindquist. Tree of Life web project, 13 December 1996. URL: (accessed on 10 April 2010)

6. Teoh, P.C., W.C. Tan, C.J. Oon, K.F. Lui, 1977. Prick skin tests in bronchial asthma and their correlation with the specific serum lgE levels. Singapore Medical Journal, 18 (4): 228-231.

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. 


Munchy Monkeys: Feeding Frenzy

People feeding macaques (from wildsingapore, 2007)
People feeding macaques (from wildsingapore, 2007)

When I was young, I witnessed many well-meaning visitors tossing peanuts to the monkeys in Bukit Timah Nature Reserve. This sight has decreased considerably ever since the feeding of monkeys in nature reserves was made a fineable offence in 1997.

Many long-tailed macaques (Macaca fascicularis) inhabit forest edges which are in close proximity to roads and human settlements. For this reason, macaque-human interactions are often inevitable. Over the decades, some macaques have grown accustomed to human feeding.

The provision of food is one of the factors leading to the high abundance and distribution of macaques near human settlement. It is estimated that more than 50% of the population obtain some of their diet from human food sources (Sha et. al, 2009a). Commensal troops are generally larger in numbers than non-commensal troops (Sha et. al, 2009a).

Twisties anyone? (from wildsingapore, 2008)
Twisties anyone? (from wildsingapore, 2008)

Provisioning can also change the behaviour of macaques (Sha et. al, 2009b). When macaques begin to associate humans as a food source, they would be attracted to human activity. This results in increased levels of interaction with humans especially at the borders of human settlements, which might escalate into macaque-human conflicts. Macaques may seize food items and other belongings from people. Some misfits also exhibit aggressive behaviour upon confrontation when they venture into homes to steal food. This further intensifies the tension between macaques and people.

People have responded to the conflict by trapping and culling macaques which are deemed to be a threat. However, we have come to realize that this is not a long-term solution to the macaque-human conflict. The management of such conflict would have to address the root cause – the feeding of the monkeys.

Please don't feed me! (from wildsingapore, 2008)
Please don’t feed me! (from wildsingapore, 2008)

1. Sha C. M., Gumert D. M., Lee P. Y.-H., Fuentes A., Rajathurai S., Chan S. (2009a) Status of the long-tailed macaque Macaca fascicularis in Singapore and implications for management. Biodiversity and Conservation, 18 (11), 2909-2926.
2. Sha C. M., Gumert D. M., Lee P. Y.-H., Jones-Engel L., Chan S, Fuentes A. (2009b) Macaque-Human Interactions and the Societal Perceptions of Macaques in Singapore. American Journal of Primatology, 71, 825-839.

Squirrels encountered along the PIE Expressway

I was amazed when I saw 2 squirrels running across the PIE expressway near my former JC- Catholic Junior College (CJC) at Whitley Road. It was an interesting yet frightening scene at that time because squirrels can be sighted in our urban environment despite the heavy traffic flow on the roads. It was later found out that the squirrels I saw were the commonly sighted plantain squirrel in Singapore- Callosciurus notatus.

Commonly sighted plantain squirrel in Singapore. Original source: Photographed in Singapore by Tan Kok Hui; taken from

Commonly sighted plantain squirrel in Singapore. Original source: Photographed in Singapore by Tan Kok Hui; taken from

According to Wildlife Singapore (2006), they usually are “active in the day and inhabit in the middle and lower storey of the forest”. However, due to clearance of forest patches for urbanization, they face a serious threat of habitat loss. Its appearance in the buzzing urban area illustrates its adaptation to urbanization (Baker, 2010).

Plantain squirrel found in parkland habitat in Singapore. Original sourve: Photo taken by Nick Baker. Retrieved from

Plantain squirrel found in parkland habitat in Singapore. Original source: Photo taken by Nick Baker. Retrieved from

Its adaptation can be explained by the environmental landscape and the feeding niche that is provided by the environment (Polechová & Storch, 2007; Wickham et al, 1998). The untouched forest within the Chinese Cemetery in Whitley area is well connected to the forest patch behind CJC through the police academy and the overhead bridge that link the school to the opposite bus stop. Even though the 2 forest patches are divided via the PIE, this connectivity allows the passage of these squirrels across the expressway, maintaining its population within the area (Wickham, 1998). Though decreased forest areas means less food resources, the man- made urban environment provide the squirrels with the feeding niche. Their diet of fruits is further supplemented by man- school’s canteen fruit juice stall with various fruits stockpiled become a rich source of food for them. The well connectivity of forest patches and the feeding niche that the environment provides allows the continuation and flourishment in our urban environment (Polechová & Storch, 2007; Wickham et al, 1998).


Ecological niche” by Jitka Polechová & David Storch, 12th August 2007. URL: (accessed on 19th March 2010).

James D. Wickham, K. Bruce Jones, Kurt H. Riitters, Timothy G. Wade and Robert V. O’Neill, 2nd May 1998. Transitions in forest fragmentation: implications for restoration opportunities at regional scales. Landscape ecology 14, pp137- 145.

Mammals in Southeast Asia Plantain squirrel- Callosciurus notatus” by Nick Baker. EcologyAsia 2010. URL: (accessed on 14th April 2010).

Wildlife Singapore: Plantain Squirrel”. Wildlife Singapore, 2006. URL: (accessed on 14th April 2010).

The Mutual Affair

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:


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?




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: (Accessed on 10th April 2010)

“Hard Corals and coral reefs” by Wildfactsheets. WildSingapore, October 2008. URL: (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: (Accessed on 10th April 2010)

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

“Coral bleaching” by Ria Tan, WildSingapore. Flickr from yahoo channel, 12 July 2009. Photo reference: 070701hntd2943. URL: (Accessed on10th April 2010)


Three blind lady beetles… see how they prey!


A group of Asian lady beetles (Steve Marshall,

Remember being fascinated by these pretty brightly-coloured “ladybirds” when you were in primary school? Frequently spotted where their prey are seen, lady beetles (Family Coccinellidae) are natural predators for countering pest control in gardens. Curiously, they seem to be able to sense the location of their prey even though they are as blind as a bat.

A common prey of lady beetles is the aphid (Superfamily Aphidoidea) (Koch, 2003). With poor eyesight, species like the Asian lady beetle (Harmonia axyridis) are dependent on “olfactory cues including the odor of the aphid-infested plant” (Obata, 1986).

In addition, lady beetles are “guided by positive phototaxis” and “negative geotaxis” (Koch, 2003), which means they respond positively to light and negatively to gravity. No, this does not mean lady beetles can photosynthesize. Rather, because aphid colonies usually congregate at upper parts of canopies (Thapa & Budha, 2008), this built-in characteristic enables lady beetles to track their prey to the top. This also explains why more aphids are consumed in light than in dark (Harmon et al., 1998).


A lady beetle feeding on foxglove aphids (

Once direct contact is made with the prey, lady beetles intensify their search for other aphids within the immediate area. And no, they do not search without strategy either. Only if the size of their prey is large enough is satisfy their appetite, they would continue their hunt in the same vicinity. Otherwise, they would abandon that area and revert back to extensive search until another direct contact is made (Nakamuta, 1985).

Knowing that these beetles possess an inherent gravitation towards light, one wonders why they are named “lady beetles” instead of  “sun beetles”…

  1. Harmon, J. P., Losey, J. E., Ives, A. R., 1998, The role of vision and color in the close proximity foraging behavior of four coccinellid species, Oecologia, v.115, p. 287-292.
  2. Koch, R. L., 2003, The multicolored Asian lady beetle, Harmonia axyridis: A review of its biology, uses in biological control, and non-target impacts, Journal of Insect Science, v. 3, no. 32, p. 16.
  3. Nakamuta, K., 1985, Mechanism of the switchover from extensive to area-concentrated search behaviour of the ladybird beetle, Coccinella septempunctata bruckii, Journal of Insect Physiology, v. 31, no. 11, p. 849-856.
  4. Obata, S., 1986, Mechanisms of prey finding in the aphidophagous ladybird beetle, Harmonia axyridis, Entomophaga, v. 31, no. 3, p. 303-311.
  5. Pfeiffer, D. G., 2010, “Lady Beetles”, Virginia Fruit Page., April 2010.
  6. Thapa, V. K. & Budha, P. B., 2008, Infestation pattern of Macrosiphum rosae and Tetranychus sp. in rose plants (Rosa hybrida) cultivated in protected and open cultivation in Kathmandu District, Journal of Natural History Museum, v. 23, p. 88-91.