LSM1303 Animal Behaviour

Shark jumping out of water

If we take a look at the general assumptions of the behavioural patterns of Great White Sharks, we see how from movies such as Jaws and other ‘B’ Grade shark movies, these animals tend to hunt and stalk their prey, waiting for the opportune moment to take a chunk out of their prey.

This viewpoint was the standard assumption until recently, when videos and pictures of a Great White Shark jumping out of the water was taken.

Therefore, this dismisses the myth of Great Whites being large and clumsy, merely capitalising on their brute force and strength to get their prey. However, as we can see from the videos and the pictures, this is entirely untrue, where they are fast, agile and nimble creatures. With this in mind, we now ask: Why do sharks “jump” out of the water? In the case of the Great Whites, they have been observed to be able to jump over 10 feet high, and covering a distance of 15 to 20 feet! This is a pretty awe-invoking image, taking note that Great Whites are the largest carnivorous sharks. Imagine the power they possess and the speed of their ascent through the water to gain enough momentum to clear 10 feet! The act of jumping out of the water by Great Whites have been known to be purely a feeding habit, where they gain speed through the water and attack their prey from below, catching them completely unaware. This may be compared to other sharks that also display such a behaviour such as mako sharks, who often does this to get rid of parasites, or an “attempt to disorientate fish”.

With such a portrayal of Great White Sharks, we find it hard to not assume that they are solitary creatures, and hence solitary hunters. However, this assumption has recently been challenged by a video of two sharks attacking a surfer at the same time, as the video below will show.

Two Sharks Attack Surfer!!

From the video, we see how two Great Whites simultaneously attack a surfer. This therefore challenges the traditional assumption that Great Whites are solitary hunters. However, the video doesn’t come without its own limitations. From the video, we can’t exactly see if these two sharks are actually cooperating to get their prey? Or if they are in reality, competing or vying for the targetted prey?

However, scientists have shown that contrary to the common myth that sharks are instinct-driven “eating machines”, recent studies have indicated that many species possess powerful problem-solving skills, social complexity and curiosity. In 1987, near Smitswinkle Bay in South Africa, a group of approximately 7 Great White Sharks collaborated to relocate the partially beached body of a whale to deeper waters to feed. This therefore highlights that Great Whites do not always hunt alone, but are actually capable of social cooperative behaviour.

After discussing the feeding and social behaviour of Great White Sharks, it is clear to see that these animals aren’t mindless killing machines as we have been led to believe, as senior reseach scientist for Marine Reseach at the Commonwealth Scientific and Industrial Reseach Organisation, Barry Bruce mentions. in addition, he also states ”They are highly evolved predators. They don’t hunt for fun. There’s no need for them to kill ten seals at a seal colony. They won’t go round biting everything in their path.”

References:

1. http://www.flmnh.ufl.edu/fish/sharks/innews/behavior2004.html
2. http://www.bbc.co.uk/nature/animals/features/287feature1.shtml
3. http://www.elasmo-research.org/education/white_shark/intelligence.htm
4. http://www.answerbag.com/q_view/2877

Yes, yes I am aware that the above expression is desperately corny and am obviously raising goosebumps and prompting gags. Yet, it must be the most appropriate summary of how female iridescent Heliconius butterflies find mating partners and possibly love! Recent research has shown that visual cues used by female Heliconius butterflies as mating signals, are made possible by polarized light. Polarized light refers to light that is reflected from shiny surfaces. White light is diffused off “20 layers of transparent scales” on the butterfly’s wings, creating the “brilliant blue” color and what we call “iridescence” of its wings. The sheer beauty of this phenomenon is so striking that passengers in planes flying over forests have picked up on the extraordinary scene.

An experiment was carried out by Sweeney who attempted to create the mating of male and female butterflies, in environments that vary in the presence of depolarizing light filters. She found out that when polarized light was created (in the absence of depolarized filters), iridescent males were more likely to approach iridescent females. Of course, the fundamental physical properties of the butterfly wings would affect such a process. Not all butterfly wings are able to create polarized light and thus, iridescence after reaction to sheer light.

heliconius butterflies mating

It might be interesting to explore the dimensions of the aged dichotomy of nature and nurture. At least from this phenomenon, we can see that nature holds certain reins but nurture and the opportunities the external environment provides to allow one to uncover natural gifts are also of importance. The Heliconius butterflies definitely cannot flaunt their shimmering hues cotteqishly in a low- white light context. As the journal articulates, “The color of … living creatures is determined by the wavelength-dependent interaction of incident light with the object.”

Butterfly wings are coated with a layer of scales which are systematically and elaborately patterned. One can get an idea of how highly intricate the structure of butterfly wings is from the extract below, taken from my choice of scientific journal:

“The upper surface of the scales bears longitudinal ridges roofed with overlapping lamellae, which covers a series of folds, perpendicular to the lamellae, the microribs. The longitudinal ridges are connected by crossribs, and together they frame so-called windows to the scale interior”.

In fact, such a physical structure of butterfly wings is highly flexible and can create a whole spectrum of possible iridescence and delightful colour, depending on the texture and quantity of light available. Isn’t it a wonder how Heliconius butterflies with their astounding colours are also known aptly as passion- vine butterflies?

Reference 

• Smithsonian Institution (2003, May 1). Butterflies Use Polarized Light To Attract Mates. ScienceDaily. Retrieved April 15, 2009, from http://www.sciencedaily.com­ /releases/2003/05/030501080033.htm.

   

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  D. G. Stavenga, S. Stowe, K. Siebke, J. Zeil and K. Arikawa, 2004. Butterfly Wing Colours: Scale Beads Make White Pierid Wings Brighter. Proceedings: Biological Sciences, vol. 271 (1548):1577-1584.  

• “Melpomene mating” by Chris Jiggins. Heliconius Homepage. http://heliconius.zoo.cam.ac.uk/heliconius/2008/129/, 24 July 2008. 
   

   

Christian, the Lion invited tons of media interest and stirred up emotions globally thus I would like to share this tear-jerking story. Born to a pair of domesticated lions, Christian was bought by two Australians, Ace Bourke and John Rendall, when he was only a few weeks old. He was domesticated until he proved too huge for Ace and John to provide him with the adequate facilities before they released him back into the wild in Africa to survive on his own. Ace and John, likened to parents worried for the survival of their “own child”, Christian, then decided to visit him a year later. The episode of Christian hugging his two owners upon reunion is definitely tear-inducing. 

Lions live in prides and all male lions are equipped to engage in dominant roles when they grow up. Their sheer size, paws and honed teeth are their weapons for physical combat to acquire territory for the smooth breeding of their young cubs by the females and for mating as well. Thus, their physical and psychological behaviour does not advocate any form of domestication like dogs or cats. However, Christian was an exception to the conventional thought that humans and wild animals are probably heaven and earth apart.

“Christian was a remarkable lion, obviously very intelligent and loving, and gentle to everyone, both human and animal.”

This brought to my attention to analyse his behaviour genetically. I vividly remember a trip to the zoo where the zookeeper in-charge of the Big Cats commented that big cats turn aggressive when they feel threatened and humans are aliens to them in the wild. However, if they are born in captivity, their parents are accustomed to meeting humans thus, they no longer find us alienating. As both of his parents are zoo lions, Christian could have inherited genes that made him less aggressive towards humans and animals. There were doubts about his ability to survive in the wild since he was never brought up in a pride and had no fatherly figure as a role model or proper parental care of a lioness. But I contend that Ace and John were his pride and they showed parental care from a human perspective. 

I also attribute his success to integrate back into the wild to his predecessor and friend, Boy. Having lived with the most intelligent mammal on earth – human, no doubt Christian learnt the powerful tool of social networking. Yet, not every domesticated big cat enjoys the same privileges as Christian. Wild lions acquire territory and they incur costs like injury or reduced foraging time. However, they gain through monopoly of food resources, stability and reduced fighting. Indeed domestication entails the exact same benefits but the costs may be unavoidable. Domestication reduces possibility of mating and mobility and if owners fail to provide adequate care, that will add bitter icing on a rotten cake. These big cats may suffer through imbalance diet or lacking both the physical and psychological ability to compete in the wild should they be released back. 

In conclusion, though I hope that some day in the near future, there will be repetitive stories of animals like Christian surfacing, I strongly feel that humans must exercise their ability to weigh benefits and costs not just for themselves but for the animals as well before they decide to domesticate another Wild animal that is purely cute to them or helps in boosting their ego.   

See also: 

“Christian The Lion – A True Story,” by Craig Andersen. 2002-2009

Big Cats Kept as Pets Across U.S., Despite Risk by Brian Handwerk. National Geographic, October 9, 2003. 

The flocking behavior of thousands of starlings, flying in incredible aerial formations, to their roosting sites before settling into trees for the night never fail to amaze by-standers. Collective animal behavior of large groups of animals, such as bird flocks, fish school and mammal herds, is a fascinating natural phenomenon. The main goal of collective behavior among individuals is to maintain cohesion of the group. This cohesion is an important requirement for survival: small groups and individuals are significantly more susceptible to predation than animals belonging to large and highly cohesive aggregations. For example, when a flock of starlings is under attack by a falcon, the flock contracts, expands, and even splits. Despite continuously changing its structure and density, no bird remains isolated, and soon, the flock reforms as a whole.

A common starling, sturnus vulgaris

A group of starling in 'aerial display'

The question to answer is: what kind of interaction enables the birds to maintain cohesion in such a robust way? One proposed theory is that individuals align and attract each other base on metric distance [Couzin et al (2002)] which they can estimate by stereovision, retinal image size and optic flow [Goodale et al (1990)]. This means that such interaction would decay when distance between individuals is increased. For example, 2 birds 5metres apart would attract each other less than 2 birds separated by 1metre in between them. However, if such interaction is based on metric distance, changes observed during predator attack cannot be explained. This is because one would expect the loss of cohesiveness of the flock when metric distances between individuals become larger than the interaction range.

An alternative hypothesis has been proposed [Ballerini et al (2008)] regarding collective behavior: individuals attract each other based on topological interactions. This means that each individual interacts and tracks a fixed number of neighbors despite their metric distance. In this case, 2 birds in a sparse flock and separated by 5metres would attract each other as much as 2 birds in a denser flock and separated by 1metre in between them, provided the number of individuals between the 2 birds is the same. The strength of interaction would thus remain the same for flocks at different densities, enabling the flock to stay together during strong density fluctuations (for example in predator attacks).

To test this hypothesis, Ballerini et al (2008) observed and reconstructed the 3D positions of individual birds in flocks of a few thousand members using stereo-metric and computer vision techniques. Computational numeric simulations were also conducted to test the topological hypothesis with the metric distance hypothesis. The research group concluded that cohesion in flocks, interacting based on topological cues, are much more robust under perturbations than metric ones, and that topologically, each bird interacts on average with six to seven neighbors.

In conclusion, collective animal behavior is an interesting phenomenon which allows large groups of animals to maintain cohesion that is necessary for survival. However, the underlying principles of interaction between the animals are still not fully elucidated, and might be attributed to topological cues between individuals.

References:

ID Couzin, J Krause, R James, GD Ruxton and NR Franks. (2002). Collective memory and spatial sorting in animal groups. Journal of Theoretical Biology 218: 1–11.

MA Goodale, CG Ellard and L Booth. (1990). The role of image size and retinal motion in the computation of absolute distance by the Mongolian gerbil (Meriones unguiculatus). Vision Res 30:399–413.

M Ballerini, N Cabibbo, R Candelier, A Cavagna, E Cisbani, I Giardina, V Lecomte, A Orlandi, G Parisi, A Procaccini, M Viale and V Zdravkovic. (2008). Interaction ruling animal collective behavior depends on topological rather than metric distance: evidence from a field study. Proceedings of the National Academy of Sciences, U.S.A. 105: 1232–1237.