LSM1303 Animal Behaviour

Mexican Axolotl

This animal that you see here is a Mexican axolotl (pronounced ACK-suh-LAH-tuhl) salamander, found exclusively in the lake complex of Xochimilco near Mexico City, The first time I saw the Axolotl, I thought it look like  a crab. The Axolotl is actually not a fish but an amphibian, a salamander, part of the order Caudata/Urodela. Axolotls differ from most other salamanders in that they live permanently in water.  I felt that this is a remarkable looking animal that we rarely come across. It worthy of note as this magnificent creature  has remarkable ability!

Axolotl is a fascinating creature. It has an amazing healing and regeneration abilities. Normal wound healing in animals occur through the growth of scar tissue, which is not the same as the original tissue. Normal wound healing also does not allow for most animals to re-grow a lost limb. However the axolotl is fully capable of complete limb re-growth. It is so amazing that it could re grow a limb. I didn’t even know an animal could do that! The Axolotl has an exceptionally large embryo. Its embryo is healthy and can be spliced and combined with different parts of other axolotl embryos with a high degree of success.

The other captivating fact about the Axolotl is that it exhibits the phenomenon known as neoteny. Normally, amphibians undergo metamorphosis of three stages from egg to larva and finally to adult form(example the tadpole of a frog is a larva) however the Axolotl, remains in its larval form throughout its life! This means that it keeps its gills and fins, and it does not develop any characteristics of other adult salamanders such as protruding eyes and eyelids. It grows larger than normal larval salamander. It also reaches sexual maturity in this larval stage. The animal is completely aquatic, and it breathes primarily through its gills even though it does possess rudimentary lungs. In the Axolotl, neoteny is now totally genetic. The axolotl will usually begin to metamorphose, when treated with hormones

Axolotls are probably one of the most scientifically studied salamanders in the world. Fortunately, even as the Axolotl is important in the scientific research, it is unheard of for them to be taken from the wild for that purpose because of the huge numbers bred in captivity each year. The disappointing thing about the Axolotl is that is an endangered species. This is largely due to the contamination of water in their captivity. I feel that the Axolotl are such fascinating creatures and it is really pitiful if we allow such remarkable creature to extinct.

Reference

Web link for Axolotl; part of Caudata.org Family
http://www.axolotl.org/

Web link from National Geographies : Mexican Axolotl 15^th April 2009

http://animals.nationalgeographic.com/animals/enlarge/axolotl_image.html

Informations and Images are ©1999-2008 John P. Clare & Caudata.org

As the saying goes, the way to a man’s heart is through his stomach. Considering that the chimpanzees share a 94% similarity with humans in terms of DNA, is it any surprise that this saying might very well apply for our ape cousins as well?

Continue Reading »

As a owner of 2 dogs, i cannot agree less with Dr Friederike Range, of the University of Vienna’s neurobiology department, with the idea that dogs feel intense jealously when they spot that they are unfairly treated compared with other dogs. When i fed dog snacks to them (something which they like very much) unequally, my dog which had less start to become fidgety and starts seeking attention. It takes more time to coax it to listen to my commands. It also displays signs of unhappiness (weak sway of the tail) when i called it. However, when i reward them separately (not in the view of each other), they were much happier and, at certain occasions, started to play with each other.

Therefore, i learnt the lesson for one to appear ”fair” in a dog eat dog world, one has to make the other party ignorant of your actions.

If this interests you, please have a look at the following articles in the reference and the comments written by other people.

Reference:

Susan Milius. (2009). Dogs will go on strike over unfair treats. Retrieved 14 April, 2009, from http://www.sciencenews.org/view/generic/id/39187/title/Dogs_will_go_on_strike_over_unfair_treats#sequence

Nora Schultz. (2008). Jealous dogs don’t play ball. Retrieved 14 April, 2009, from http://www.newscientist.com/article/dn16216-jealous-dogs-dont-play-ball.html?DCMP=OTC-rss&nsref=online-news

Rebecca Carroll. (2008). Dogs can feel envy, study suggests. Retrieved 14 April, 2009, from http://news.nationalgeographic.com/news/2008/12/081208-dogs-envy.html?source=rss

  The Hyena is a mammalian family of order Carnivora.  Hyenas are native to both African and Asian continents.  They consist of four living species, the Striped Hyena and Brown Hyena (genus Hyaena), the Spotted Hyena (genus Crocuta), and the Aardwolf (genus Proteles).  Hyenas generally live in packs which are led by a matriarch.  In hyena society, the females are the dominant gender.  This trait is shared by all four sub-species.  The spotted hyena goes one step further, with females being larger in size than males.  This article, by analyzing two studies on hyenas, aims to show that both nature and nurture play important roles in contributing to this unique gender dominance in spotted hyena society.

            In a study which made it to the international science journal Nature, Michigan State University zoology professor Kay Holekamp, her former graduate student Stephanie Dloniak and Jeffrey French from the University of Nebraska, reported that high-ranking, dominant spotted hyena mothers pass to their offspring high levels of certain hormones that make cubs more aggressive and sexually vigorous.[1]  This allowed cubs to have a better chance of surviving to adulthood and reproducing.  The study found higher levels of androgen during the final stages of pregnancy in the more dominant females as compared to the lower-ranking group members.[2]  These hormones played a significant influence on the behaviour and appearance of the offspring.  “What this means is that there are gifts a mom can give to her baby. She can manipulate her offspring’s behaviour and help her kids to survive and reproduce successfully by transferring status-related traits via prenatal hormone exposure,” said Holekamp.[3]  In addition, the maculinizing effects of androgens causes females to gain greater muscle mass, aggressive behaviour and dominance. More aggressive females are better able to compete for food when hyenas squabble over kills.[4]  This study supports the nature theory.

            The second study published in the scientific journal Behavioral Ecology suggests that dominance is more a case of nurture, and that hyenas inherit their social status.  An international team of scientists from the Leibniz Institute for Zoo and Wildlife Research (IZW) in Berlin, Germany, and the University of Sheffield, UK, used observations during the last 20 years of rare cases of adoption among hyenas in the Serengeti and Ngorongoro Crater in Tanzania in combination with the latest molecular techniques to identify genetic mothers to demonstrate that hyena mothers pass on their social status by supporting their young during social interactions with other group members.[5]  In spotted hyena society, social status is highly important.  It determines access to resources, survival and reproductive success.  As a result, parents may attempt to pass on their status to their offspring. “In spotted hyenas, surrogate mothers adopt young cubs soon after their birth. The adopted cubs obtained a rank at adulthood that was similar to and just below the rank of their surrogate mother. In contrast, the rank of adopted offspring was unrelated to the rank of their genetic mother” says Dr Marion East from the IZW. “This is consistent with the idea that maternal behavioural support determines rank inheritance.”[6]

            The results of the second study however throw into doubt two existing hypotheses explaining dominance in spotted hyenas.  The first being that mothers might transfer genes that cause their offspring to be as competitive as themselves; and the second being, maternal status might determine the concentration of maternal androgens that a foetus is exposed to, and this exposure in turn might make offspring become as competitive as their mother. “These hypotheses would predict a relationship between the rank of adopted offspring and that of their genetic mother, but we found no evidence of such a relationship” explains Dr Oliver Höner from the IZW.[7]  The study suggests that hyena young learn as they grow which group members they can dominate when their mother helps them win contests against group members that are subordinate to the mother.  As they grow older and reach adulthood, they continue to defend the privilege passed down to them.[8]

            To conclude, it is my believe that it is impossible to split the cause of hyena dominance to either simply nature, or nurture alone.  They both play apart in contributing to hyena dominance.  Perhaps maybe more so in hyena society as compared to any other species, hyenas need the heavy mixture of both nature and nurture to attain their aggressiveness and dominance to continue surviving and reproducing.

The Kiwa hirsutra dubbed as the Yeti Crab of the Pacific

Yeti of the Pacific? Check out the furry resemblance!

“Marine biologists have discovered a crustacean in the South Pacific that resembles a lobster or crab covered in what looks like silky fur” (BBCNews, 2006). This animal is a unique discovery and a new taxonomic family has been created just for it. It now belongs to the newly named family called “Kiwaida”, named after the goddess of crustaceans in Polynesian mythology. It is white and 15 cm long, according to Michel Segonzac of the French Research Institute for Exploitation of the Sea.

The special feature of this animal is its furry pincers. The Kiwa hirsutra is said to habitate in some Pacific deep sea hydrothermal vents, which spew out fluids that are toxic to many animals. The furry pincers also contain lots of filamentous bacteria, which could either be used to “detoxify poisonous minerals from the water, allowing it (K. hirsuta) to survive around the vents” (BBCNews, 2006) or serve as food for the animal. 

This special feature could possibly a result of evolution, to allow the animal to survive in harsh conditions like the hydrothermal vents. A detailed study of this animal could be found in the journal article “A new squat lobster family of Galatheoidea (Crustacea, Decapoda, Anomura) from the hydrothermal vents of the Pacfic-Antarctic Ridge” (Macpherson et. al, 2005).

Citations:

“Furry lobster found in Pacific,” by BBCNews, 8 Mar 2006

“A new squat lobster family of Galatheoidea (Crustacea, Decapoda, Anomura) from the hydrothermal vents of the Pacfic-Antarctic Ridge” by Macpherson et. al, 2005, Zoosystema 27(4): 709-724

Guess what’s being served tonight… If you are a dung beetle of the Scarabaeidae family, you may feast on a gastronomic delight of freshly laid fecal matter, otherwise known as dung!

Quick facts on the dung beetles                        

 Dung beetles are found in every continent except Antarctica.

They are organized into three main groups according to their behaviour; the rollers, tunnellers and dwellers.

The anatomy of a dung beetle consists of 3 body parts namely the head, thorax, and abdomen. It has wings for flight and 6 legs, with the hind pair longer and well-adapted for foraging purpose. Their acute sense of smell helps them locate food, which is mainly dung(Thomas, 2001).

Unique behaviour

They are interestingly known for ‘the (dung) ball-rolling action’ of the rollers. Dung beetles are regarded as important players in ecosystems as they break down and remove dung. This contributes to nutrient recycling, soil aeration and seed dispersal(Viegas, 2006).

Ball-rolling behaviour of dung beetles

Due to the competitive nature of securing food, some species are observed to “sit and wait” at dung source such as the genital and anal regions of the brown titi monkeys in Peru (Jacobs, Nole, Palmenteri, & Ratcliffe, 2008)

Genital region of a brown titi monkey infested with C. guadriguttatus beetles.

 (Source: Jacobs et al.2008)

Feeding on dung

 Dung beetles feed on herbivorous animals’ waste. The dung ball is the prime food source for most species of dung beetle for its complete metamorphosis from single egg to larvae to pupae and new adult. The adult breaks out to the surface and then feeds on fluid from the ball that is extracted by squeezing the dung in its mouthparts.

Attracting the females through food

During the mating season, the male dung beetles use the dung ball to attract females. The mating pair work together to roll brood balls away from the dung pat. She will lay a single egg in it after it is buried. The grub feeds on the material when it hatches.

Latest trend on foraging behaviour: Done with dung?

Deltochilum valgum species of dung beetle living in the lowland rain forests of Peru have apparently taken on a more predatory role in seeking for food(Morgan, 2009). Not known for their predatory instincts, these beetles are adding live millipedes on top of their “traditional menu of dung, fungus and fruit.” Scientists attribute this strange evolutionary transition as driven by high levels of competition for food. Adult dung beetles compete intensively for resources, both between species and within species(Morgan, 2009).

Sources:

Jacobs, J., Nole, I., Palmenteri, S., & Ratcliffe, B. (2008). First Come,First Serve: “Sit and Wait” Behaviour of Dung Beetles at the Source of Primate Dung. Neotropical Entomology , 37 (6), 641-645.

Retrieved from http://www.scielo.br/pdf/ne/v37n6/a03v37n6.pdf  on April 9, 2009.

Morgan, J. (2009, January 21). BBC News, Science & Environment. Retrieved April 9, 2009, from Little dung beetle is big chopper: http://news.bbc.co.uk/2/hi/science/nature/7840404.stm

Thomas, M. (2001). Dung Beetle Benefits in the Pasture Ecosystem. Retrieved April 6, 2009, from ATTRA, National Sustainable Agrivulture Information Service: http://attra.ncat.org/attra-pub/dungbeetle.html#appear

Viegas, J. (2006, May 3). Animal Planet News. Retrieved April 9, 2009, from Dung Beetles in Trouble?: http://animal.discovery.com/news/briefs/20060501/dungbeetle.html

Brains or balls… If you can only have one, which would you have?

What a painful decision to make (I am guessing this… since I am not the male in question).

However, in the case of bats, this choice was made through evolution - Bats with smaller brains have bigger testes and bats with bigger brains ended up with the smaller testes.

In a fascinating study done by a research team led by Syracuse University biologist Scott Pitnick, it was found that in bat species with promiscuous females, the males had the largest testicle. However, these bats also sported the smallest brains. Conversely, in populations with faithful females, the male bats ended up with smaller testicles but bigger brains.

It is postulated that if female bats mate with more than one male (meaning a ‘promiscuous’ female), there would be sperm competition amongst the males. In such a case, the male who ejaculates the greatest number of sperm would win the game which is a possiblity behind the evolution of outrageously big testes in male bats from populations with promiscuous females.

This finding (of bigger brains with smaller testes and vice versa) has been tied down to the evolutionary tradeoff between intelligence and sexual prowress by many researchers. It is speculated that there exists a negative evolutionary relationship between the bats’ investment in testes and brains (as both are metabolically expensive tissues and it is extremely costly on the bats to maintain both in tiptop conditions i.e. HUGE).

In fact, according to the article, there has been a growing body of evidence which indicates that costly sexually selected traits (and these includes testis and ejaculatory traits) can tradeoff against other energetically expensive but important characters, such as immune function.

The possibility that investment in either extravagant sexually selected traits such as testes, or other similarly energetically expensive and important body parts or organs such as brains, would constrain investment in the other has certain implications in lieu for the sexual selection theory. It would seem to be that though the brain size could influence reproductive behaviors, sexual reproduction which favors larger or smaller investments in resource intensive organs, ornaments or armaments could similarly influence the brain and behaviour. So it might be too simple to assume your brain rules all. It seems likely that the brain is a result as well as a cause.

This tradeoff between brains and balls makes one wonder about humans, doesn’t it?

Would a more promiscuous society eventually result in males with smaller testes but larger brains? It doesn’t seems like a optimistic picture would be in view for the males of the future if that is indeed the case. However, luckily for the guys, humans are much more complicated organisms and there would probably be a lot more factors that might be involved in this tradeoff - It is unlikely that human males would lose either their brains or their balls.

(Do I hear a collective sigh of relief in the background…?)

References

Pitnick, S., Jones, K. E., & Wilkinson, G. S. (2005). Mating system and brain size in bats. Proceedings of The Royal Society B.

Ruvinsky, J. (2006). Secrets Of Bat Machismo. http://discovermagazine.com/2006/may/bats.

I loved this movie when I was in primary school (don’t we all???) so I was super excited when I got to watch it recently again. I was curious on how Willy was doing (in real life) so I began wikipedia-ing whales in general.

I would never have imagined what I found out.

WHALES (WILLY INCLUDED) COULD HAVE BEEN THIS WOLF-LOOKING CREATURE ABOUT 50 MILLION YEARS AGO!!!

Can you believe it?!?!?!

I’m sure you guys are all thinking: how is that possible! How could a large, big brained, land-walking animal evolve over the years to a swimming creature, an ocean dweller and live its entire life in water?

Call it an unfinished story.

The extraordinary evolution of whales started 50 million years ago. It was said that in less than 10 million years, the whales’ ancestors completely transformed themselves from four legged terrestrial animals to Today’s ocean dwelling giants. During the transformation, they lost their legs and all their vital organs required to live on land. Instead, they gained gigantic fins and cute little panda eyes (in Willy’s case of course). Pakicetus, was the oldest known early whale and can be said to be the “transitional” animal between the terretrial mammals and earliest true whales. This small furry wolf-like animal can now be found in the lands of Pakistan. Similarities between the two can be found:

• Their need to breathe air from the surface;
• The bones of their fins, which resemble the jointed hands of land mammals; and
• The vertical movement of their spines, characteristic more of a running mammal than of the horizontal movement of fish.

I managed to find a timeline of the evolution to share with everyone. Isn’t it just extraordinary?

Of course, some details still remain fuzzy,such as gaps in the fossil records and investigations and research are still undergoing. However, scientists have made recent discoveries in Pakistan. They have managed to solve many of these mysteries, and it is now possible to see several stages in the transition of the cetaceans from land to sea. The video below shows the detailed explanation of the scientists’ research:

http://channel.nationalgeographic.com/series/morphed/3001/facts#tab-Videos/06300_00

It might be unbelievable.. that Willy’s ancestors used to live on land. But it’s true! As evolutionary biologist Neil Shubin points out, “In one sense, evolution didn’t invent anything new with whales. It was just tinkering with land mammals. It’s using the old to make the new.”

This got me thinking… Since whales used to have legs.

Can Humans…

do the opposite of a whale evolution & live in the sea afterall?

References:

“http://channel.nationalgeographic.com/series/morphed/3001/facts#tab-facts” When Whales Had Legs. National Geographic Channel, April 8 2008.

“http://en.wikipedia.org/wiki/Evolution_of_Cetaceans” Wikipedia: Evolution Of Cetaceans (Last Accessed: 14 April 2009)

“http://www.pbs.org/wgbh/evolution/library/03/4/l_034_05.html” Evolution Library Website: Whale Evolution (Last Accessed: 14 April 2009)

TheLiger

The Island of Dr. Moreau is a late 19th century novel about a scientist who experiments with animals and human-animal hybrids. Whether such human-animals hybrids exist or not (I hope not), I am not aware. These myths are horrifying and the book presents it in a similar nightmarish fashion of the perils of scientific research. On a lesser scale but no less mystifying is the Liger, an extremely large 10 feet tall, 450-kilogram cat which is the hybrid of a lion and a tiger.

The Liger is essentially a hybrid of a male Lion (Panthera Leo) and a female tiger (Panthera Tigris). The Liger has attributes of both the lion and the tiger, for instance, they have the ability to both roar like lions and chaff like tigers. The Ligers enjoy swimming like a tiger and are social creatures like the lion. These creatures can devour a meal of up to 23-kilograms in meat of beef, elk, venison or chicken. One of the Ligers bred in captivity called ‘Hercules’ can actually grow up to 12 feet tall and chalk up to 50 miles per hour when running in full speed. To call these creatures’ monsters, is less condescension than a reality given their physical capabilities.

Ligers can grow up to 12ft tall.

There is a suggestion from www.messybeast.com that the reason for the size of these animals is what is known as “growth dysplasia”. When a male lion mates with a tigress, his genes promote large offspring because lions are adapted to a competitive breeding strategy. The tigress does not inhibit the growth because she is adapted to a non-competitive strategy. Therefore the offspring (liger) grows larger and stronger than either parent because the effects do not cancel each other out. Though ligers take several years to reach full adult size, it is a myth that ligers never stop growing. However, when a male tiger mates with a lioness, his genes are not promoting large growth of the offspring because he is adapted to a non-competitive breeding strategy. However, the lioness is adapted to a competitive strategy and her genes inhibit the growth of the offspring. This uneven match means that the offspring (tigons) are often smaller than either parent.

However, growth dysplasia has other effects: the size of the placenta may be affected (causing miscarriage), the embryo may be aborted at an early stage due to abnormal growth, the cub may be stillborn or may only survive a few days. In some rodents, mating Species A males with Species B females produces offspring half normal size, but mating Species B males with Species A females cause the offspring to be aborted as they try to grow to several times the normal size.

It is important to note is that such hybrids are more possible in captivity then in natural habitats. This is one that transcends the mere habitat differences between the tiger, found largely in Asia and the Lion found largely in Africa. According to the Natural Geographic: “ “Crossing the species line” does not generally occur in the wild, because “it would result in diminished fitness of the offspring,” said Ronald Tilson, director of conservation at the Minnesota Zoo in Apple Valley.” There are cases in the Wild Animal Safari in Pine Mountain, Georgia, where 3 out of the 24 successfully bred Liger, that died out of “head shakes”, a kind of neurological disorders. Because, the park officials were unable to deduce what went wrong in autopsies, they attributed it to genetic disorders. This might explain why these creatures are sterile, as a natural way of preventing such hybrids that might not actually survive in the wild.

Because these Ligers do not have a wildlife existence, so theoretical postulations on their behavior and the possibilities of their survival of the hybrid should suffice. What is necessary for a hybrid to survive in real life is to separate a population (either through geography or habitat) and then let the two camps evolve into distinct species. Other variations are also possible, where two different species have mated — creating an offspring that is different from the parents.  Even assuming that they can reproduce, the survival of these hybrids relies on them being reproductively and ecologically isolated. According to LiveScience: “Reproductive isolation means the hybrid cannot mate with one of its parent species.  If this were not the case, then the offspring of hybrid and parent would have less genetic uniqueness, thereby foiling the creation of a separate species”. Hybrids also need to have their own ecologic isolation, otherwise they will likely be out-competed by their parent species.  If these conditions are fulfilled, hybrids are less likely to be a fantasy from science fiction or the tempering of human beings but actually a distinct natural probability given the right circumstances.

Not 'monsters' but a biological possibility.

Something to think about: Can 'we'/humans become hybridized with other species?

Main Reference

“Ligers Make a “Dynamite” Leap into the Limelight” by Maryann Mott. National Geographic News, August 5th 2005. http://news.nationalgeographic.com/news/2005/08/0804_050804_ligers.html (Last Accessed: 10th April 2009).
Other References

“The 10ft Liger who’s still growing…” Daily Mail Online News, February 16th 2005. http://www.dailymail.co.uk/news/article-338009/The-10ft-Liger-whos-growing-.html (Last Accessed: 10th April 2009).

“Zonkeys, Wolphins and Ligers: Nature Loves a Hybrid” by Michael Schirber. LiveScience, 27th July 2005. http://www.livescience.com/animals/050727_hybrid_flies.html (Last Accessed: 10th April 2009).

http://www.messybeast.com/genetics/growth-dysplasia.htm (Last Accessed: 10th April 2009).