It is known that nonhuman primates are intelligent. However, what surprised me was that apes in this case orangutans, have the ability to make intelligent choices in the selection of mates. I always thought this only applied to humans. I knew animals make conscious choices but I thought the criteria were simple and basic.

The National Geographic article highlights the intelligence of female orangutans when it comes to the choice of a mate. The females are cunning and smart. Their criteria for a mate? Low aggression. They want to make sure their mate will not be aggressive to them if they do not follow what the male wishes especially in the area of mating. These female orangutans use tests to measure the male’s aggressiveness and in this case, by stealing the male’s food to see how he would react (Kaplan, 2009).

Female Orangutan with food

Source: http://www.flickr.com/photos/89211937@N00/210687592/

A study showed that female primates face sexual coercion from the males. Males find it costly in terms of time and energy to impress the female. Instead of wasting their energy, they use force. For orangutans, if the female is not in the mood to copulate, the male will overcome the female’s fierce resistance with violent restraint. These acts of violence may result in abortion, death of the female and disruption for estrous cycle. The study goes on to say that females are starting to find methods to gain control. With this control, they can choose to mate only during mid cycle (Slater, Rosenblatt, Milinski and Snowdon, 1993).

Thus, the National Geographic article shows us one of the ways that female orangutans have learned to overcome violent mates by testing them. If the males are overly aggressive, the females will choose not to associate with these males. This is interesting as it is very much like human behaviour. Females may manipulate and test males to see what his true nature is like.

It seems that we may not be so different from our nonhuman primate counterparts afterall.

Are we really that different?

Source: http://www.flickr.com/photos/diankarl/2282864243/

References

“Orangutan Females Steal Food to Test Potential Mates,” by Matt Kaplan. National Geographic, 2 April 2009.

Slater, P. J. B., Rosenblatt, J. S., Milinski, M & Snowdon, C. T, 1993. Male aggression and sexual coercion of females in nonhuman primates and other mammals: Evidence and theoretical implications. Advances in the Study of Behaviour, 22: 1-30.

   Who needs Fire Breathers when you have these Fast and Furious foul-mouthed Monsters ???!!

http://www-tc.pbs.org/wgbh/nova/sciencenow/3209/images/01-diam-komodo-l.jpg

Komodo dragons have survived in the harsh climate of Indonesia’s Lesser Sunda Islands for millions of years, although amazingly, their existence was unknown to humans until about 100 years ago.
Reaching 10 feet (3 meters) in length and weighing more than 300 pounds (136 kilograms), Komodo dragons are no doubt, the heaviest lizards on Earth. They have long, flat heads with rounded snouts, scaly skin, bowed legs, and huge, muscular tails.

When hunting, Komodo dragons rely mainly on camouflage and patience, lying in wait for passing prey. When a victim ambles by, using the element of surprise, the dragon springs up on its prey.With its powerful bowed legs, sharp claws and serrated, shark-like teeth, the dragon eviscerates its prey.

Animals that escape the jaws of a komodo dragon, will only feel lucky briefly. Although the Komodo dragon doesn’t breath fire, it’s mouth contains death. Dragon saliva teems with over 50 strains of virulent bacteria, and at least 4 types of toxic bacteria. After bitten by a dragon, the stricken creature will die of blood poisoning.

The dragon’s shark-like tooth serrations harbor bits of meat from the dragon’s last meal and Komodo dragons also frequently bite through their own gums as they eat. The lethal saliva and blood combination and the protein-rich residue in the teeth thus provide an ideal culture for the bacteria. A Komodo’s bite causes profuse bleeding and are slow to heal.

Although a dragon is not always successful in immediately bringing down a large animal, the bitten animal usually dies within a week. Infected by the bacteria, its wounds turn septic (septicemia). The Komodo dragon then tracks the weakened animal as the bacteria takes effect, for miles, using their keen sense of smell, harassing it until the animal finally dies. However, it is also interesting to note that if a Komodo is bitten by another Komodo, it doesn’t suffer any deathly effects. The anti-coagulating properties of the Komodo’s saliva, and natural immunity to each other’s saliva is being investigated for human medical applications.

Kills with One Bite – Video

http://www.youtube.com/watch?v=q7CQInAXoqY

References :

B.G. Fry, N. Vidal, L. van der Weerd, E. Kochva and C. Renjifo, Evolution and diversification of the Toxicofera reptile venom system, J. Proteomics 72 (2009), pp. 127–136.

B.G. Fry, Structure-function properties of venom components from Australian elapids, Toxicon 37 (1999), pp. 11–32.

J.J. Calvete, Digging into the evolution of venomous systems and learning to twist nature to fight pathology, J. Proteomics 72 (2009), pp. 121–126.

Website: National Geographic http://animals.nationalgeographic.com/animals/reptiles/komodo-dragon.html, Retrieved on 1st April, 2009.

Picture taken from :http://www-tc.pbs.org/wgbh/nova/sciencenow/3209/images/01-diam-komodo-l.jpg

Video Extracted from : YouTube http://www.youtube.com/watch?v=q7CQInAXoqY&feature=related

A recent study done on female orangutans has revealed that the primates engage in kleptoparasitism or food stealing to test out the level of aggressiveness of their potential mates. When their male counterparts reacted violently to having their food snatched away, female orangutans “screamed and tended to end the interactions much sooner than when the male tolerated the stealing”.

Female orangutans steal food from males to test out males' aggressiveness. Photograph by Steve Raymer. Source: National Geographic.

Male-male aggression is seen as attractive to females as it provides a physical display of the male’s virility and offers greater protection against threats. However, violent behavior towards females on the other hand, severely limits their ability to mate with other males as and when they wish. Females trapped in a relationship with an aggressive male would be forced to abide by his preferences, or risk incurring his wrath.

Being attacked by an aggressive male orangutan is not merely a case of playful shoving. Injuries sustained by the female can range from bruises to even broken bones if she is knocked off from elevated areas such as trees or rocks.

Nevertheless, researchers observed that males who did tolerate the food stealing and passed the aggressive behavior ‘test’ were not immediately rewarded by females who were ready to ‘jump in the sack’, so to speak. Rather, researcher Maria van Noordwijk believes that “stealing allows females to test males for their tendency to be aggressive toward them so they can determine whether they are worth further associating with”.

Derived from article:

Kaplan, M. (April 2, 2009). Orangutan Females Steal Food to Test Potential Mates. Retrieved April 5, 2009, from National Geographic. Website: http://news.nationalgeographic.com/news/2009/04/090402-orangutan-food-test.html

Related article:

Brockmann J.H. & Barnard C.J. (2004). Kleptoparasitism in birds. Animal Behavior, 27(2), 487-514. doi: 10.1016/0003-3472(79)90185-4.

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.