LSM1303 Animal Behaviour

A spiny puffer fish courtesy of ocean explorer

The puffer fish can be found in many of the world’s oceans, freshwater and even brackish water, making it seemingly omnipotent. The sight of a puffer fish inflating itself has fascinated many children and adults alike around the world. However, behind this cute and seemingly innocuous persona, the puffer fish hides a deep dark and deadly secret.

Ranging from 2.5cm to 61cm long, it is the propulsion mechanism that led to the puffer fish having to evolve its deadly mechanism. A puffer fish uses a combination of pectoral, dorsal, anal and caudal fins to move itself around, giving it great manoeuvrability but very lousy speed. Put a puffer fish next to its predator, the tiger shark, and that would be like having your Kangoo van racing with a Ferrari. Hence, to cope with its shortfall, the puffer fish has evolved 2 defence mechanisms.

When under attack, the puffer fish will rapidly inflate itself, filling a special sac in its body with water and air swelling up to an amazing 1m in some instances. This makes it extremely hard for the predator to grip it. Even if the predator somehow manages to get a hold and chomps down on it, the puffer fish’s stomach is very elastic, making it hard for the predator to deflate it for consumption. Watch the video to see for yourself! Puffer fish being axed

Notice how difficult it is to hang on to the puffer fish.

A puffer fish day dreaming in the sun may still become lunch for the lurking predator. However, predators are unlikely to survive for long once they have consumed the puffer fish and this is why. In the belly of the fish lies one of the deadliest poison know to man, tetrodotoxin. This toxin is believed to be created by the puffer fish through the bacteria that it consumes. Its lethality is compounded by the fact that there is no known antidote to this poison. Tetrodotoxin has been known to kill humans in half an hour and is 1200 times more toxic than cyanide. For those who don’t know, cyanide is that little pill that all spies like James Bond carry with them to avoid capture. 25 milligrams of tetrodotoxin can be expected to kill a 75kg man. Deadly.

Despite its lethality, certain animal species like tiger sharks have evolved to display immunity to this toxin, making them the few successful predators or puffer fishes.

Fugu Sashimi in Japan

On a side note, thousands of Japanese dice with death every single day when they consume the puffer fish. Known as a delicacy in Japan, specially trained chefs are equipped with the skills to remove the deadly poison from the fish to make it fit for consumption. However, due to the fact that tetrodotoxin can kill even in minute quantities, incomplete removal of the poison by chefs has been known to cause deaths every year in Japan. Some plucky diners take it one step further, consuming pieces of the fish where an extremely small amount of the poison has been left on deliberately by the chef, all for an opportunity to flirt with death.

Reference:

Ebert. K (2001). The puffers of fresh and brackish waters, Aqualog 2001, ISBN 3-931702-60-X

(n.d). Pufferfish. Retrieved from http://animals.nationalgeographic.com/animals/fish/pufferfish.html

Hachquet. C (2002). What are Puffer Fish?. Retrieved from http://www.essortment.com/all/puffersfish_rbgg.htm

Material Safety Data Sheet Tetrodotoxin ACC# 01139. Retrieved from

https://fscimage.fishersci.com/msds/01139.htm

Nora, an adopted grey tabby, has won fame for playing the piano. This rare behavior was apparently self-taught or innate, when she climbed on top of a Yamaha Disklavier piano in the middle of the night and began to play. The couple who adopted Nora owns an art and music studio, where students play the piano in the day. The owners of Nora observed that she has a preference to play on the Yamaha Disklavier piano, even though there are other pianos in their studio. She also includes black keys in her music (http://www.youtube.com/watch?v=TZ860P4iTaM), and plays duets with the students (http://www.youtube.com/watch?v=v0zgQAp7EYw).

From both videos, it does seem like Nora is musically inclined and not just “fooling around” with the piano. Is her sense of music innate or is there some other reason for her bahavior? A 2001 National Geographic article “Do Animals Have an Innate Sense of Music” suggests that animals, including birds and mammals like whales use many musical concepts, such as rhythm, phrase lengths and song structure in their communication. This may help to explain Nora’s sense of rhythm when playing the piano.

However, a piano is an unnatural musical instrument for an animal. Although the owners claim that Nora is self-taught, one might think it’s more probable that Nora might have went through “observational learning”, where the owners taught students to play the piano in the day when Nora was around. Since Nora was also described as being attention loving, the huge amount of attention thrown onto her following her piano-playing incident might have served as a positive reinforcement for her to do it again.

While the rare behavior of Nora has yet been explained satisfactorily, it is most reasonable to suspect that an interplay of the cat’s innate musical abilities and subsequent learning through observation can account for the phenomenon.

References

“Do Animals Have an Innate Sense of Music?”, by Jen Mapes. National Geographic, 05 Jan 2001.

“Nora (Cat)“, Wikipedia. Date accessed: 12 Apr 2009.

The Malayan sun bear (Helarctos malayanus) is the smallest among the eight living bear species in the world. They have short, sleek fur to suit the climate of the tropical rainforest of Southeast Asia. They are named sun bear due to their chest patch, which is individually distinct. Do you remember the ever popular cartoon character, Winnie the Pooh? Honey, being the favorite of the Winnie the Pooh, origin from this bear! They have the longest tongue among all bear species, so as to be able to extract honey from the bee hives with ease. With feet which are turned slightly inward, large naked paws and long curved claws, the sun bear are excellent climbers. This enables them to have even more access to honey.

Sun bear cubs are born blind, deaf, hairless and helpless. They are blind due to their short gestation period of approximately 100 days. In humans, our gestation period is around 10 months. A long period of gestation period allows the brain to develop more fully and hence, the infant will be born with their eyes open. However, the sun bear’s short gestation period means that the cub’s brain will have to continue growing after birth. Their eyes can only be fully open and utilized after additional neurological development. Upon development, their eyes will open about a month later. Since the cubs are blind and helpless, they cannot leave the nest. The mother will move and carry the cubs in her mouth or in her forepaws everywhere she moves.

The sun bear are not the only animal that is born blind. Mice, squirrels, bats and rabbits are born blind, hairless and helpless too, largely due to their short gestation period. Due to this characteristic, they would be kept warm, protected and fed by their parents until they have grown up. On the other hand, animals like the deer have a longer gestation period of around 200 days. As such, deer are born with their eyes open and they can walk around almost immediately after birth.

References:

Stephen Cardiff, 28 Feb 2009, “Sun Bear”, Scienceray, Retrieved 12 Apr 2009, from http://www.scienceray.com/Biology/Zoology/Sun-Bear.562439

“Raising Mammal Young”, Wild Mammals of Illinois, Illinois Department of Natural Resources, Retrieved 12 Apr 2009, from http://dnr.state.il.us/education/CLASSRM/wild_mammals/pdf/unit1_4.pdf

Dr Debra Bourne, “Life Stages with literature reports for the Sun Bear- Helarctos malayanus” , Retrieved 12 Apr 2009, from http://wildlife1.wildlifeinformation.org/S/0MCarnivor/ursidae/helarctos/Helarctos_malayanus/07Helarctos_malayanusLifePhys.html

Suzanne Hall, 12 Dec 2009, “Sun Bears: Growing Up Great”, Zoological Society of San Diego , Retrieved 12 Apr 2009, from http://www.sandiegozoo.org/wordpress/default/sun-bears-growing-up-great/

“Malayan sun bear (Helarctos malayanus)”, Arkive, Retrieved 12 Apr 2009, from http://www.arkive.org/malayan-sun-bear/helarctos-malayanus/info.html

Before Baygon was invented

It was a nice, cool night. Looking at the calendar I realized that the examinations were 2 weeks away.With a sickly feeling in my stomach I picked up my pen and started realizing. Suddenly I noticed that I wasn’t alone in my room; it was a moth ( a Hofmannophila pseudospretell a.k.a the Brown House Moth). Feeling mildly irritated, I pick up a book and bat it out of room through the window. Thinking that was the end of it, I settled back to my revision. But to my horror, that bugger bug flies right back in and promptly starts circling my tablelamp with a mothy smirk on his face.

OK, maybe I imagined the last bit. But have you ever wondered why that, at night, as soon as you open the windows your room quickly fills up with these uninvited guests? Such a scenario is not uncommon. At night, hundreds of insects can be seen flying around street lamps or any bright light source that just unfortunately happens to be in the area. It is called photoaxis; the behavior of being attracted to lights.

Now, photoaxis can be broken down into 2 categories: Positive and Negative photoaxis. A positive photoaxis would indicate an attraction to light sources. This would be that moth currently above my head and out of reach, circling my ceiling lamp while gloating at me. A Negative photoaxis would indicate an avoidance of light sources, pretty much the same way how a drunk would react when you shine a torch at him.

So what exactly do these insects find so romantic in out lamps even when there are other natural light sources out there. Well, apparently even to this day there is no clear answer! Some scientists have put forth a theory that such behavior is a Function; they use light as a navigational aid, and by keeping the sun or moon on one side of its body they can ensure that they are always in the right direction; which is why moths, in confusing our lamps with the moon, circle the lamp in an attempt to keep the light source on one side (Michael Pollick 2003). Another theory suggested is that, in cases where insects are photoaxis negative, the attraction to dark places is a way of hiding from predators (Leather et al. 1995).

However, one must note that, although the effect of light on insects that are photoaxis negative/positive have been clearly documented, it is important to remember that even though we know how insects see the world, we do not know exactly WHAT is it that they see. Different insects are also attracted to different sorts of lights; moths to UV light, incandescent light for flies and mosquitoes, greenlight for stored food insects and so on (Capinera, J.L. 2008). Note however, that while some insects may be attracted to artificial light, they may keep away from sunlight, indicating that light intensity does affect these bugs behavior.

So the million dollar question of how you can keep those bugs away at night? Well, simply put you can’t. Not unless you use light that is bright enough to blind yourself at the same time, or you switch off your lights and use nightvision goggles to read your books. And even then you will have another problem to deal with; photoaxis negative insects like cockroaches.

References

1. Capinera, J.L 2008, Encyclopedia of Entomology 2^nd ed, Springer pg 3869

2. Leather S. R. , Walters K. F. A. , Bale J.S. 1995, The Ecology of Insect Overwintering, Cambridge University Press pg21

3. Michael Pollick 2003 Why are Insects Attracted to Light? Accessed at http://www.wisegeek.com/why-are-insects-attracted-to-light.htm on 110409

4. National Library Board Singapore Why are Insects Attracted to Light?. Accessed at http://blogs.nlb.gov.sg/ask/children/119 on 110409

Picture from: http://news.bbc.co.uk/cbbcnews/hi/newsid_4720000/newsid_4721600/4721697.stm

This odd looking little fellow does look like an alien, doesn’t it? The bright yellow cap that dwarfs its small body is actually a piece of sponge cut to fit each individual sponge crab. The marriage between sponge and crab may seem incredulous especially if you are thinking of the bath sponge we use at home. But sponges and crabs actually live in close proximity in coastal areas including Singapore’s Chek Jawa and Pulau Semakau.

The sponge crab first finds an appropriate sponge and cut it to its size with its sharp pincer claws. The new living sponge cap is then gripped by the crab’s hind legs, which have evolved to be able to bend over its back and pin the sponge in place. This special behaviour functions to camouflage and protect the crab from its predators. When not moving, the sponge crab looks just like another blob of spongy material on the ground. The bad taste of the sponge also deters predators from eating the sponge crab.

Seeing how important their sponge covering are, it is not surprising that these crabs have developed a mechanism to secure their caps. The study by W.S. Dembowska details the mechanism of making a covering fit the sponge crab’s body. Other covering material may also be used when sponges are not available. The flip flops you left behind at the beach may end up as a headwear for one of these incredible animals!

To discover more interesting facts about the crabs that dress up, click here.

References:

“Dresser crabs are abundant but hard to spot”, by Susan Scott, Ocean Watch, January 02, 2004

Dembowska, W.S., 1926, Study on the Habits of the Crab Dromia vulgaris M.E, Biological Bulletin, Vol. 50, No. 2, Marine Biological Laboratory, pp. 163-178. Accessed at http://www.jstor.org.libproxy1.nus.edu.sg/stable/1536681?seq=1

“Sponge Crabs”, by Ria Tan, WildFactSheets Website, 2008