LSM1303 Animal Behaviour

Does your pet know when you are coming home? There have been lots of experiments that say, while you are gone, your pet actually “feels” when you are ready to return, even while YOUR mind is on more pressing personal matters. Recent studies have shown, while incorporating real and hard core scientific protocols that your pet may sense FAR more than we think, and may have a connection to our consciousness that surpasses SOME science fiction novels. This article talks about whether animals really have heightened senses than we can imagine. To us, humans, we call it the sixth sense.

Can Animals Really Be Psychic? Read This and Find Out.IanHollander(n.d.) http://www.streetdirectory.com/travel_guide/194318/pets/can_animals_really_be_psychic__read_this_and_find_out.html

CAN ANIMALS DETECT WHEN THEIR OWNERS ARE RETURNING HOME?

AN EXPERIMENTAL TEST OF THE ‘PSYCHIC PET’ PHENOMENON. Richard Wiseman, Matthew Smith (n.d.) https://uhra.herts.ac.uk/dspace/bitstream/2299/2285/1/902380.pdf

Gastric-brooding frogs (Rheobatrachus silus) in Southeastern Australia were observed to possess unique parental care to their eggs. After external fertilization by the male, the mother “swallows its own eggs”. The offspring were incubated in the mother’s stomach at the prejuvenile stage. However, the species became extinct in the mid-1980s before more discoveries were made.

“Gastric-brooding frogs: swallows her own eggs”, 06 May 1006, http://digg.com/d14ErP

Gastric Brooding: Unique Form of Parental Care in an Australian Frog. C. J. Corben,

G. J. Ingram, and M. J. Tyler, 1976. Journal of Science, 186(4167): 946-947.

In the process of courtship, different people look for a variety of traits and characteristics for their potential mates. This is no different in the animal kingdom. When dealing with mate choice in the animal kingdom, one might consider terms like sexual selection, female choice, intra-specific competition (i.e. competition amongst the males for access to females), courtship displays and so on.

One of the most stunning examples of courtship displays can be found in Peafowl. In Peafowl, Peacocks (male) possess long tail feathers, knows as a train, and the Peacocks spread out their trains in a beautiful display. It has long since been the understood that the females (Peahen) will choose their mates according to the size, colour and quality of the Peacock’s train. This however, has been throw into fresh doubt.

Researchers from the University of Tokyo have supposed found out that it is not the train of the Peacock that the females are attracted to, but vocalizations that the male makes when displaying its feathers!

” … the scientists think that male mating calls, which consist of multiple notes and sound very different than the noises females make, could affect mating success. The trains, on the other hand, may just be obsolete signals at this point, they suggest.”  (Discovery News)

The Peacock’s train feathers have bewildered many (including Charles Darwin, who famoulsy said that the sight of feathers made him sick), with its apparent hindrance to the Peacock’s survivability as described in the video “Tale of the Peacock”. The Peahen often seems disinterested in the Peacock’s train feathers, while continuing to peck at the ground for food. However, scientists have conscientiously observed the females and their mate choice and concluded that females lay more eggs for males with the largest trains.

Furthermore, if Peahens were indeed attracted to the Peacock’s vocalizations and calls it would go against reasoning of evolution and sexual selection ; the Peacock would not have taken such lengths to have such an extravagant tail and probably developed a more elaborate song repetiore or otherwise, to differentiate and have a better advantage against competing males.

Studies and experiments have also shown that females do indeed prefer those with longer trains and bigger “eyespots”. All these explanations serve only to belittle the controversial claims made by researchers from the University of Tokyo, yet there still could be space to discover something new about sexual selection or sexual evolution.

I wonder what Charles Darwin would think =)

References:

“Female Peacocks Not Impressed by Male Feathers” by Jennifer Veigas. Discovery News, March 26, 2008.

“How Did the Peacock Get His Tail?” by Sanjida O’Connell. The Independent (London), September 9, 2002.

“The Ant and the Peacock: Altruism and Sexual Selection from Darwin to today” by Helena Cronin, John Maynard Smith. Cambridge University Press, 1993.

“Sexual Selection and the Barn Swallow” by Anders Pape Moller, Jens Gregersen. Oxford University Press, 1994.

“Tale of the Peacock” credits to WGBG Educational Foundation and Clear Blue Sky Productions, Inc.

“Handbook of Evolutionary Psychology: Ideas, Issues, and Applications” by Charles B.Crawford, Dennis Krebs. Lawrence Erlbaum Associates, 1998.

Photograph courtesy of John Rite, http://www.flickr.com/photos/johnrite/605236060/

We are well familiar with the Eiffel Tower, Sydney Opera House and even the Great Wall of China. But as impressive as these human architectures are, we have equally (or some would say, even better) awesome architects in nature: the Termites.

Certain species of Macrotermes and Amitermes build huge mound nests which are more than 10m in height. Amitermes are also known as magnetic termites due to the way they orientate their flat and broad protruding mounds which are along the north and south axis of the Earth. Unlike us, in which we can employ the help of heavy machinery and tools to aid in construction today, the termites built their enormous mounds solely relying only on their own strength. Bit by bit, each worker places a “brick” of building material, consisting of nothing but the soil in their vicinity, probably mixed with a bit of their saliva for cementing purposes.

Why the high and conspicuous mound you might ask. The reason is ventilation. Nests like these house large colonies of termites, some reaching a population of a million strong. With such numbers in an enclosed place, it can get truly hot. Acting as a chimney, the protrusion draws away heat and exchanges it with cooler fresh air. In addition to a chimney, these mound nests are fully equipped with a “well’ at the bottom in which the termites draw precious water.

The designs of these mounds serve several functional purposes like thermoregulation, ventilation and hydration. Moulded and fine-tuned overtime through evolution, they stand the trial of time. It is indeed fascinating to see such elaborate structures constructed by these little creatures working in great unison with such efficiency. But exactly how it is they communicate to each other to achieve such cooperation to the most minute of details, we don’t yet know.

 BBC Home Making: Termites

Termite World – Life in the Undergrowth – BBC Attenborough

References

Korb, J. and Linsenmair, K. E., 2000. Thermoregulation of termite mounds: what role does ambient temperature and metabolism of the colony play? Insectes Sociaux, 47:357-363.

Korb, J., 2003. The shape of compass termite mounds and its biological significance. Insectes Sociaux, 50: 218-221.

BBC Home Making: Termites. Accessed 9 April 2009.

http://www.youtube.com/watch?v=ld07xdqnytk

BBC – Life in the Undergrowth: Episode 3. Accessed 9 April 2009

http://www.youtube.com/watch?v=xGaT0B__2DM

Cricket infected with parasitic worm commits suicide 

Ever heard of suicide in the animal world? A study by Sanchez et al. (2008) reveals that among many insects, the cricket (Nemobius sylvestris) has been especially noted to display suicidal tendencies, though its suicidal behaviour is not a result of its own agency but rather induced by parasitic hairworms (Paragordius tricuspidatus). Infected by a juvenile parasitic hairworm, the host cricket leaps into water where it often drowns to its death, while the juvenile hairworm conveniently leaves the cricket to become a free-living adult in an aquatic environment where it can mate and reproduce. This is significant as the hairworm is required to be in aquatic habitats in its adult stage while it can survive in non-aquatic habitats in its juvenile stage, and also because the adult hairworm only has a narrow temporal window to reproduce successfully in water. In this light, parasite-host relations between the hairworm and the cricket reveal how the former manipulates the latter to its own advantage on 2 counts. Firstly, by altering the behaviour of the cricket in a way that increases its encounter rate with water, and secondly, by manipulating the cricket to reach water at an optimal time for hairworm reproduction.

The parasitized cricket’s induced behaviour unfolds in 2 stages: firstly, it displays erratic behaviour, leaving its forest habitat. Then, its behaviour becomes suicidal when it encounters a water feature, causing it to leap to its death. However, this transition from stage 1 to stage 2 is not fixed as not all the erratic crickets’ jump into water when they encounter it. This is further supported by results of a study by Thomas et al. (2002) on whether hairworms manipulate the water seeking behaviour of their terrestrial hosts, which points out that in both field and lab experiments, “only 50% of the infected crickets (N. sylvestris) went toward the water and entered it”. Although both the 2002 study as well as this study are unable to find reasons as to why not all erratic behaviour of the crickets would transit into suicidal behaviour, both studies suggest that this change in the behaviour is likely to be adaptive. In fact, this study suggests that the erratic stage is “not simply a prelude to suicide as systems within the cricket break down”; for instance, the high cost of predation would be associated with the erratic behaviour of the crickets leaving the forest habitat. Both studies hence conclude that further investigations would be needed to determine if such behaviour of the crickets is indeed adaptive.

As for the parasitic hairworm, this study predicts a trade-off between its manipulative and reproductive efforts based on optimality theory, which recognizes both costs and benefits and suggests that traits have evolved to be the best they can be under existing conditions. This is because the necessity of the hairworm to find water to reproduce indicates that “it is undoubtedly better to maintain manipulation of the host at a high level even if this leads to a reduction in fecundity, rather than decreasing the manipulative effort to keep a potential fecundity that would be useless in the absence of water”. However, as “hairworm fecundity may decrease not because manipulative costs increase” and as the hairworm’s manipulative efforts cannot be quantified, “further studies in controlled conditions would be necessary to confirm the existence and nature of such an interesting trade-off” between the hairworm’s manipulative and reproductive efforts.

References

Harper Collins Publishers, 2003. Suicidal grasshoppers. Retrieved April 8 2009 from: <http://www.voyageronline.com.au/news/0510scifacts.cfm>.

M. I. Sanchez, F. Ponton, A. Schmidt-Rhaesa, D. P. Hughes, D. Misse and F. Thomas, 2008. Two steps to suicide in crickets harbouring hairworms. Animal Behaviour, Vol. 76 (5): 1621 – 1624. 

F. Thomas, A. Schmidt-Rhaesa, G. Martin, C. Manu, P. Durand and F. Renaud, 2002. Do hairworms (Nematomorpha) manipulate the water seeking behaviour of their terrestrial hosts? Journal of Evolutionary Biology, Vol. 15 (3): 356 – 361. 

Yves Elie, 2002. “Le Manipulator”. V.B. Films. Retrieved April 8 2009 from: <http://www.youtube.com/watch?v=D7r1S6-op8E>.