LSM1303 Animal Behaviour

When I think hippopotamus, I think of huge hairless mammals with stubby legs and an enormous mouth. And yes, hippopotamuses are one of the largest mammals on Earth in terms of their weight. They do have a big mouth. And, even with stubby legs, hippopotamuses are able to outrun humans. Amazing! And if you watch them closely, they do provide nice resting zones for birds.

pretty-scratched up hippo

Jokes aside, these animals may seem mild and clumsy, spending most of the time submerged in the water. But they can become very aggressive when it comes to competition, territoriality or protecting the young. The first video narrated by David Attenborough highlights how gruesome fights between two hippopotamuses can get. However, it is the second video that I find hard to digest!

http://www.youtube.com/watch?v=BUer8Dv2HW8

Animals have different ways of marking their territories. Some of them engage in physical aggression while others use psychological intimidation. The hippopotamus, believe it or not, flings a mixture of poo and urine to mark its territory. The alpha male will wags its tail as it defecates to ensure that the excrement spreads over the greatest possible area. The hippopotamus does this both on land (bushes and shrubs) and in water. This area that is scented with the animal’s droppings is, therefore, its territory. Animal Planet ranks this act eighth on the list of Top 10 Animal Gross-Outs.

http://www.youtube.com/watch?v=sIZSb8uiuck

Do not be anywhere near a hippopotamus. Do not drink from any river if you are in sub-Saharan Africa.

Sources:

The Ultimate Guide to African Wildlife 2007 Tthe Large Mammals of Africa Retrieved 14th April 2009 from http://www.africanwildlifeguide.com/species-guide/mammals/large-mammals/hippopotamus

Animal Planet 2009 Top Ten Animal Gross-Outs: Hippo Retrieved on 14^th April 2009 from http://animal.discovery.com/tv/a-list/creature-countdowns/gross-outs/gross-outs-08.html

Hippopotamus Retrieved 14^th April 2009 from http://www.flickr.com/photos/25961625@N08/3011651583/

Hippopotamus 2008 Retrieved 14^th April 2009 from http://www.flickr.com/photos/25961625@N08/3012487648/

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).

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.

Hyena at the Ngorongoro Crater in Tanzania. (Credit: iStockphoto/Sebastien Burel)

Unlike most mammals, the social organisation of the spotted hyena is a matriarchy. The leader of the pack is a dominant female. And this dominance is encouraged and even heightened, argues zoologist Kay Holekamp, by both biological and sociological reasons.

According to Holekamp, the “length of time it takes for the massive skulls and jaws of hyenas to mature in youngsters” and ”feeding competition typical of hyena clans” cause the females to develop dominant behaviour and compensate for their youngs’ inadequacies. It also does not help that the males, as like most mammals, do not contribute to the rearing of their offspring.

A mother spotted hyena and cub. (Credit: Courtesy of Kay Holekamp)

Developing aggression as a favoured trait is further encouraged by the findings that higher ranking hyena females pass certain hormones that make their cubs more aggressive and sexually vigorous. This enables them to survive and thrive compared to their peers.

Besides these biological traits, hyenas also inherit their social status. If you watch the 1992 Production by National Geographics Eternal Enemies: Lions and Hyenas, this social structure is clearly evident. The role of the matriarch in establishing the order, however, is even clearer when she dies (not surprisingly from an attack by a lion). A small portion was captured on youtube.

Eternal Enemies: Lions and Hyena

Arctic ground squirrels are the largest of the American ground squirrels and have their optimal habitats in the Northern latitudes. Their habitat spans from Alaska in the USA, to provinces in Canada such as the Yukon, Northwest Territories and Nunavut. Arctic ground squirrels live in colonies and build burrows in areas of well-drained soil with views of the surrounding landscape. These squirrels have a diverse and opportunistic diet and feed on the seeds, leaves, roots, stems and flowers of arctic shrubs and plants. They sometimes also eat the meat of freshly killed animals in a bid to store up as much fat in the short sub-arctic winter.

Source: Author

The arctic ground squirrel’s physiological adaptations to the harsh condition of a long sub-arctic winter include hibernation. They usually enter hibernation once they have enough body fat to last the winter –usually around late August to mid-September. When entering into hibernation these squirrels burrow up to three feet below the ground with a layer of insulating snow above.

Once in a state of hibernation, the core body temperature of the squirrels drop to a “supercooled” state of about -2 degrees Celsius –the lowest known body temperature of all mammals. In this supercooled state, the squirrels’ brain, thoracic, and abdominal cavities were maintained above freezing points while peripheral temperatures were below freezing. Despite being below freezing points, the squirrels’ bodily fluids continue to flow, thus keeping the squirrel alive throughout winter whilst minimizing energy loss. At intervals of two to three weeks, the squirrels shiver and shake for up to 12 to 15 hours to warm up their temperatures slightly, then allowing their temperatures to drop again after the shivering stops.

Source: Author

How does the squirrel stay alive despite its body temperatures being below freezing? Studies done by researchers at the University of Alaska, Anchorage and Fairbanks, as well as the University of Calgary have shown the supercooled state of the Arctic ground squirrels is possible because of a very gradual temperature drop. This physiological adaptation to the harsh winters of the sub-Arctic region has occurred despite the risk of immediate death should nucleation (immediate freezing due to presence of ice nucleator in the gut) happen due to the benefits (in terms of energy saving) that is accrued to the squirrel in maintaining such low body temperatures. The benefits of saving approximately 10 times more energy has resulted in the physiological adaptation of the arctic ground squirrel despite the apparent risks.

Source: Author

Scientists are seeking to further understand how the arctic ground squirrels enter a supercooled state and are literally frozen alive, in order to apply this physiological adaptation to improved preservation of transplant organs.

* All images taken 15 September 2008, Denali National Park, Alaska.

References

National Park Services (2006), Denali National Park and Preserve – Arctic Ground Squirrel. http://www.nps.gov/dena/naturescience/arcticgroundsquirrel.htm.  Accessed on 2 April 2009.

Manning, Elizabeth. The Long Sleep – Which Animals Hibernate?, http://wildlife.alaska.gov/index.cfm?adfg=wildlife_news.print&articles_id=279&issue_id=48&attributes.hidehead=1&attributes.hidetail=1. Accessed on 2 April 2009.

Muldrew, Ken (1999), Mammalian Hibernation, http://www.ucalgary.ca/~kmuldrew/cryo_course/cryo_chap12_1.html. Accessed on 2 April 2009.

Berreby, David (1996), Discover Magazine – Running on Tundra, http://discovermagazine.com/1996/jun/runningontundra787. Accessed on 2 April 2009.

Kunjan, R. Dave et al., (2006), The Arctic Ground Squirrel Brain is Resistant to Injury from Cardiac Arrest During Euthermia, Stroke – Journal of the American Heart Association, 37:1261-1265.