LSM1303 Animal Behaviour

Our creature of interest: The Spitting Cobra

Source: http://dsc.discovery.com/news/2009/01/21/cobra-venom.html

Recently, a curious creature that has come into interest is the cobra. Its name has often been borrowed to name military programmes. We have in Singapore the Cobra Division, Exercise Cobra and the AH-1W Cobra Helicopter. We say imitation is the best form of flattery. Just look at the Cobra Division Badge Patch Design(below); it’s pretty telling.

It gives accolodes to the cobra’s deadly strike and swift immobilising power. But within cobras, some species have evolved this unique mechanism that’s patent-worthy. The spitting cobra has this unusual ability to jet venom out into the eyes of a would-be predator/attacker. This defence mechanism works in very simple steps: Enter the potential predator. Cobra engages its head and neck muscles. Muscle contractions squeeze the cobra’s venom gland, forcing venom to stream out of the snale’s fangs. There is enough fluid pressure to spray venom beyond six feet (ScienceDaily).

When we explore the dynamics involved in this unique artillery, there’re more reasons to feel awed by this creature. Firstly, the venom does not spray out randomly. The venom streams out in complex geometric patterns which’re actively controlled by the cobra. Secondly, the potency of this weaponry is how it maximises the chances of striking the eyes. There’re no points won for hitting other parts of the body, deterrence only occurs when the accoster is hit in the eyes. If we check out the spitting cobra’s scoreboard, we may feel fascinated or mortified(for those of us who’ve never hit the bull’s eye in dart-throwing or archery); cobras hit their targets with alarming frequency; nearly 100% accuracy from 60 centimetres away (tad bit disconcerting huh)! Like every master archer, it fixates its gaze on its target; the eyes. And its target maximising strategy works like this: It rotates its head rapidly when squirting the toxin, increasing the spatial distribution of venom and creating a higher chances of striking bull’s eye! Dr Westhoff, a member of the research team which derived for us these findings, states “Rather like we do when we wish to use a garden hosepipe to water the flowers of an entire flowerbed.” To think about it, this technique is almost state-of-the-art.

But this unique morphology is only exclusive among a few species of cobras. Through a narrow channel in their fangs, the cobras spew venom out when pressure is exerted via muscular contractions(ScienceDaily). When we think about it, it’s almost like the make-up of our water pistols, just with more finesse. Not all spitting cobras are equal in their marksmenship though (nature does endow us unfairly). The black-necked spitting cobra (below) hits its goal in only 80% of target practice. The red mozambique(below), however, achieves a 100% full score.

The Black-necked Spitting Cobra

Scoreboard: 8/10

Source: http://www.conservationsafaris.com/Pictures/Black-necked_spitting_cobra.jpg

Red Mozambique Spitting Cobra

Scoreboard: 10/10

Source: http://i.livescience.com/images/h_spitting_cobra_02.jpg

That’s a powerful weapon to have in your arsenal, no doubt, but it must have high energetic costs too. Which is why spitting cobras do not eject venom randomly. The sprewing action is released by an external stimulus; moving objects. A study conducted by the University of Bonn revealed that the spitting action can be triggered by a moving human face or a moving human photo( Westhoff et al,2005). Stationary objects do not stimulate any action. Furthermore, the cobra does not spit blindly, it can differentiate between human faces and hands(since the ultimate target are the eyes)! The spitting cobra does not waste its venom if you wave your hands before it just to give you a free show.

Accosting a spitting cobra

Source: http://www.wildlifeextra.com/images/large-brown-spitting.jpg

All that military jargon would no doubt have us thinking that the spitting cobra is a rather gladiatorial, hawk-like creature. But that ain’t true; there’s no need to feel overly threatened by this creature. It only attacks when threatened. And a further boon: It hunts in the same manner as other snakes; by biting its prey with its fangs. Which means it doesn’t depend on this for its bread and butter. Consider having such a formidable auxiliary weapon in your arsenal! This gives it an additional edge over ordinary cobras against its traditional arch-rival and nemesis, the mongoose. Intuitively speaking, the evolving of unusual defence functions are usually in response to real world challenges and constraints.Some scientists theorize that the development of the spitting mechanisms were the result of these cobra species cohabitating with numerous antelop species. They believe that the primary function of the fangs are to prevent being trampled on by hooves. By spewing venom when necessary and deter the onslaught of hooves(Tigerhomes Sanctury website).

It has a drawback though; it is useless against oncoming vehicles!But it comes into mind every time we’re aiming at the dartboard or in a watermelon spitting contest. Before you go, do take a look at the following video depicting the confrontation between the spitting cobra and lion. It shows our centerstage creature triumphing against the grunting, huffing lion, who then scampers away. Follow the slow-motion trajectory of the venom stream and notice that it’s jets out in double, not single streams which run almost parallel to each other. On this, researchers found that spitting cobras don’t spray as a stream, mist or cloud. The venom sprays out in distinctive patterns, typically paired ovals (Discovery News) When I described the venom spray as “state-of-the-art” earlier, I meant it.

Video: Spitting Cobra Vs Lion (http://www.youtube.com/watch?v=_5dtpMj9Ehs)

References:

Westhoff, G, Tzschatzsch. K, Bleckmann H. (2005). Journal of Comparative Physiology A: Neuroethology, Sensory, Neural and Behavioral Physiology. Vol 191(10). pp 873-881.

Science Daily (Jan 26, 2009). Here’s venom in your eye: Spitting Cobras Hit Their Mark. From http://www.sciencedaily.com/releases/2009/01/090122152709.htm. Accessed on April 13, 2009.

Science Daily(Feb 17, 2005). When Cobras Spit, There’s Not A Dry Eye In The House. From http://www.sciencedaily.com/releases/2005/02/050212194818.htm. Accessed on April 13,2009.

Tigerhomes.org Animal Sanctuary. Spitting Cobra-Fangs, Captive Breeding, Pictures, Baby Spitting Cobras. From http://www.tigerhomes.org/animal/spitting-cobra.cfm. Accessed on April 13,2009.

Jennifer Viegas, Discovery News. (2009). Spitting Cobra’s Sharp-Shooting Secrets. From http://dsc.discovery.com/news/2009/01/21/cobra-venom.html. Accessed on April 13, 2009.

Toad ‘riding’ on a carp

Ever seen a carp piggy- backing a toad? This is it. I was flipping through the newspaper and was drawn to a really interesting photograph that featured a toad ‘riding’ on a carp. However, as I read on, I found out that the poor carp was eventually ‘sexually abused’ to death by the toad!

This is the link to the article:

http://news.wenxuecity.com/messages/200902/news-gb2312-788428.html?SubID=news&MsgID=788428&c_lang=big5

As link is from an online Chinese newspaper agency website, I have translated it as below:

It was the time of the year for the breeding season of toad starting from September to March. In a farm of Taiwan, approximately ten toads gathered at the pond and began their harassment of the inhabitants there. This incident took place on last year’s December where two toads of 6- 7 cm long managed to grasp hold of the heads of two carps respectively. Despite the struggle of the carps to get free, their efforts were futile. The relentless ‘clinging’ of the toads on carps lasted for 4 days and finally ended with the tragic death of the carps. According to biologist Dr Qu, the death of the carps could be due to the possibility that the carps had swallowed the venom of the toads and such an act may be a display of mating behavior of the toads which coincided with the concurrent breeding season of the toads. Others suggested the possibility that the death could be caused by extreme exertion of force on the carps or infection.

Wood frogs in amplexus

Now viewing from a more scientific perception, the toad’s display of this special kind of embrace is referred to as amplexus. As you can see from the photograph above, the smaller sized male is always on top of the female during mating. The male will grasp the female’s trunk with his forelimbs and external fertilization will occur outside the female’s body. During amplexus, the female discharges eggs into the water while the male will fertilize them by shedding sperms over the eggs. By comparing both photographs, it is clear that the toad had mistaken the carp as his mate!

This is an interesting video which I found for frogs in amplexus. Your may wish to have a look.

 Attenborough: Golden Frog: Fighting & Mating – Life in Cold Blood – BBC wildlife

 Appalled and awed by this carelessness of the toad? Well, yes I am. AND this is not the only ‘spouse mistaking’ incident that has ever occurred. There are also other instances where this happened on other toads as well (picture below). In fact, according to a study conducted by Dr. Susumu Ishii in Japan, it was found that when adult male toads find ANY pliable object as large as an adult toad during the breeding season, they will mount and try to clasp it. Sounds ‘despo’? I think so. Even if the object they have mounted does not respond, they will persist and keep holding on for hours or even for days. This was the tragedy that befell on the poor carp. However, if the object is a ‘mentally prepared’ female for mating, amplexus will proceed under normal circumstances. On the other hand, if the object mounted is a ‘mentally unprepared’ female for mating, she will send vibrational signals through her body. Upon receipt of the vibrations, the clasping male will then loosen his grip and back off.

The link to the article on the study conducted by Dr. Susumu Ishii is as follows: http://www.backyardnature.net/frogsex.htm

Toad clasping a Green Frog

I really felt sorry for the two dead carps. Looks like the toad have to do some soul- searching on his ‘despo’ character or should at least wear a pair of spectacles to help him spot his right ‘bride’ the next time. If not more may fall victim and suffer under his ‘love’ or I should say ‘forbidden love’.

Reference

1. Apple Daily (Taiwan), (7 February 2009), retrieved on 14 March 2009. http://news.wenxuecity.com/messages/200902/news-gb2312-788428.html?SubID=news&MsgID=788428&c_lang=big5
2. ‘Frog Reproduction’, by Conrad Jim, 14 March 2009. http://www.backyardnature.net/frogsex.htm
3. ‘Wood Frog’, by Rana Sylvatica, 17 March 2009. http://www.uri.edu/cels/nrs/paton/LH_wood_frog.html
4. Attenborough: Golden Frog: Fighting & Mating – Life in Cold Blood – BBC wildlife, 17 March 2009. http://www.youtube.com/watch?v=A1FWQvaBoRg

In past researches on dogs, it is almost believed that yawning in dogs is not a sign of tiredness but rather an indication that the dog is suffering stressing conditions from the surroundings. This is because yawning is able to increase heart rate and blood flow to the brain and helps to fill the lungs with oxygen. Thus, yawning helps a dog to energize its body and stays alert to respond to potential threats.

However, due to close socialization between human and our domestic canine buddies over thousands of years, man could affect how dogs behave and react overtime. A team led by Dr Senju, conducted an experiment and concluded that although at times, yawning in dogs is a response to extreme stress, the true reason for why contagious yawning is catching is not fully understood for now. However, a reason for dogs’ yawnings could be due to the fact that they have the capacity for a fundamental form of empathy towards human beings. 

Am I tired? or am I not?

To further the research, the team created two conditions. For the first experiment, a stranger sat in front of the dog and calls its name. “We gave dogs everything: visual and auditory stimulus to induce them to yawn.” said Dr Senju. Under this condition, the stranger yawned once the dogs had made eye contact with them. As for the second condition, the auditory stimulus was taken off as a precaution to ensure that dogs were not responding to an open mouth. Out of 29 dogs from a wide range of dog breeds, 21 of them responded to the yawning, while no dogs yawned during the non-yawning scenarios.

The experiment

“There are theories that seem to think that we used to transfer this information of ‘I am tired’ by yawning when we didn’t have language,” Joly-Mascheroni told LiveScience. In a way, humans could be indicating sleepiness to dogs. “It would be interesting to find out what other information we transfer to dogs or to any other animals that we are not aware of,” he added.

With great curiosity, I have conducted my own “yawning induction experiment” on my dog Happy. Like what was stated as the conditions, I called her name, waited for her to make eye contact with me and yawned with action and sound. Happy could not be bothered with me for the first time but responded upon the second trial!

Go ahead! Try yawning to your dog next time and see what happens!

            References:

1)     Pet dogs can ‘catch’ human yawns, http://news.bbc.co.uk/2/hi/science/nature/7541633.stm, by Jennifer Carpenter,  BBC new, 5 August 2008

2)     Dogs Catch Human Yawns, http://www.livescience.com/animals/080917-dogs-yawn.html by  Jeanna Bryner, 17 September 2008

3)     Dogs can ‘catch’ yawns too, http://www.brudirect.com/DailyInfo/News/Archive/Aug08/080808/wn01.htm, retrieved on 13.4.2009

4)     Dog Body Language, http://www.justusdogs.com.au/dog-pages/all-about-dogs/552/dog-body-language.cfm, retrieved on 13.4.2009

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

Archaeopteryx

Scientists agree that dinosaurs are ancestors of today’s birds. But just why did some of them sprout wings? Until now, the answers offered have often be referred to a better chance of escaping from predators. But researchers at the University of Manchester have advanced a more subversively romantic notion: they suggested that sexual selection- which gives animals an advantage in choosing a mate- may have been the key factor. In the evolutionary process known as sexual selection, traits viewed as more attractive by the opposite sex become both more common and more pronounced, since mating animals gravitate towards them.

Sexual selection may have played a bigger role in the evolution of flight than had been previously thought

The models of Archaeopteryx and two other feathered dinosaurs, Caudipteryx and Protarchaeopteryx, suggest that forelimbs would have been inefficient as early wings, since they provide little thrust and increase drag. As a result, in evolutionary terms, these wings would have given the creatures little competitive advantage over rivals.

However, past research has shown that Archaeopteryx and other birds are homologous and had an aerodynamic function. [ Richard O. Prum, 2003]

It all seems so mind- bloggling, so what is the wings of dinosaurs really for? Dr Paul Barret, a palaeontologist at London’s  natural history museum, observed that the truth may be in a mix of factors. But well, no one can say that you are wrong if you give an answer like ” Cause it was sexy.”

Reference:

Dinosaurs takes to air, Richard O. Prum, 2003, from http://bill.srnr.arizona.edu/classes/182/DinosToTheAir.pdf

Dinosaurs may have evolved wings to attract mates, Richard Gray, 04 Apr 2009, from http://www.telegraph.co.uk/scienceandtechnology/science/dinosaurs/5105218/Dinosaurs-may-have-evolved-wings-to-attract-mates.html

Dinosaur attracting mates, from http://www.zeenews.com/from-the-past/2009-04-07/521328news.html

YES. the title is not deceiving at all. The kinky animal I will be mentioning in my blog post does practise oral sex while mating.

Cichlid fish (courtesy of Paul Wheeler)

I stumbled upon an article from sciencedaily.com which featured Cichlid fish. Cichlid fish are a family of fish which includes Tilapia and Angel Fish. It has been discovered that after female Cichlid lays her eggs, she picks them up and carries them around in her mouth. The male Cichlid on the other hand has a gene that produces spots on his anal fins to resemble the eggs. He swims by the female and upon seeing the fake eggs, thinking her eggs had fallen out, she swims towards him and attempts to suck the eggs back into her mouth. The male Cichlid then takes advantage of this situation and deposits his sperms into her mouth!

This is a short video of the mating process:

cichlid mating!! –> do watch it. It’s very interesting.
A study in the journal BMC Biology conducted by Walter Salzburger, Ingo Braasch and Axel Meyer, identifies that the gene in male Cichlid Fish, scientificaly known as colony-stmulating factor 1 receptor (or csf1ra) ”produces yellow pigment cells in oval spots on the fishes’ fins”. These yellow pigment markings are also known as egg-dummies, are generally located on the anal fins of the male fish and are essential to mating.

In another study, evolutionary biologist Ole Seehausen and his co-authors demonstrate that female cichlids whose eyes are more sensitive to blue tend to prefer blue-coloured males, while females with photoreceptors better able to detect red light choose males with red nuptial coloration. These different visual receptors are present because of DNA and protein sequences and all these shows that natural selection is involved in the mating between the Cichlid species.

Isn’t the way these cichlid fish mate just bizzare?

If you want to read up more about this and the challenges posed to these fish in recent years, do visit this link.

References:

“Gene in Male Fish Lures Females into Sex“, BioMed Central (19th November 2007).

“New Fish Species may emerge because of how females see males“, EAWAG: Swiss Federal Institute of Aquatic Science and Technology (2008, October 2).

“Adaptive sequence evolution in a color gene involved in the formation of the characteristic egg-dummies of male haplochromine cichlid fishes” , Walter Salzburger, Ingo Braasch and Axel Meyer (Published online 15 November 2007)

“Cichlid Fish Diversity Threatened by Eutrophication That Curbs Sexual Selection“, Ole Seehausen, Jacques J. M. van Alphen and Frans Witte (19 September 1997)

While out in the field at night, one occasionally can notice a gecko without its tail. This rather strange looking individual has autotomised its tail (which is part of its body part) and this process is scientifically known as autotomy.

Autotomy is defined as the ability to voluntarily shed a body part, typically along a predetermined breakage plane (Wasson et.al., 2002). This unusual behaviour is relatively widespread in certain animal groups and has been observed in rodents, salamanders, lizards, crabs, spiders and sea stars (Juanes and Smith, 1995). As different groups of animals have developed and maintained this behaviour, this implies that there must be strong selective benefits to it.

Spider with missing leg

Why do animals choose to autotomise their limbs or body part? Several reasons have been proposed. Firstly, autotomy enables the animal to reduce injury to body parts. For example, certain species of crabs are known to break off their injured limbs. Secondly, this allows the animal to distract a predator and enable it to get away without being eaten. For example, certain lizards will often drop their tail when grasped in order to escape from predators.

Lizard missing part of the tail

However, losing a limb or a body part does not come without any cost and the animal may be at a disadvantage when its limb is temporarily absent. Firstly, the animal may suffer from a reduced ability to forage or defend. For example, when a crab loses a cheliped, it will be less capable in feeding and defending against potential predators. Secondly, the animal will also have to expend precious resources to regenerate the lost body part. This will come at the expense of growth and reproduction.

In conclusion, autotomy can be beneficial to the animal and may be important for survival in certain animals. However, it is not without any negative impacts to the animal.

Literature Cited

Juanes, F. & L. D., Smith, 1995. The ecological consequences of limb damage and loss in decapod crustaceans: a review and prospectus. Journal of experimental marine biology and ecology 193: 197-223.

Wasson, K., B. E., Lyon  & M. Knope, 2002. Hair-trigger autotomy in porcelain crabs is a highly effective escape strategy. Behavioral Ecology, 13, 481–486.