LSM1303 Animal Behaviour

Killer Whales VS Sea Lions

The video above depicts two killer whale siblings on a hunt for their prey. What is extraordinary about the video is that after they have consumed the daily required intake, they start playing with their prey and return it back to the shore from whence it came. This act of mercy has confounded behavioral scientists alike; instead of just eating the prey or perhaps leaving it to fend for itself, the whales actually brought it back to its original location.

Early descriptions of “whale killers” or “killers of whales” gave rise to the common name killer whale. More in vogue is the name orca, from the species’ scientific label, Orcinus orca, but for those who know Latin, “whale from the underworld of the dead” is hardly an image upgrade. Strictly speaking, orcas are not whales. They are the world’s largest, brawniest dolphins, found in every ocean. With enormous reserves of speed and strength, one of the biggest brains in existence—four times the weight of a human’s—and no natural enemies as adults, they have staked a claim as the supreme predators across 71 percent of the planet. What do they do when they meet a great white shark? Lunch, according to witnesses.¹

They feast on marine mammals such as seals, sea lions, and even whales, employing teeth that can be four inches (ten centimeters) long. They are known to grab seals right off the ice. They also eat fish, squid, and seabirds. Though they often frequent cold, coastal waters, orcas can be found from the polar regions to the Equator. Killer whales hunt in deadly pods, family groups of up to 40 individuals. There appear to be both resident and transient pod populations of killer whales. These different groups may prey on different animals and use different techniques to catch them. Resident pods tend to prefer fish, while transient pods target marine mammals. All pods use effective, cooperative hunting techniques that some liken to the behavior of wolf packs.²

The act of mercy as shown in the video has not been restricted to only killer whales. Other species have been known to exhibit this tendency too. Foxes have been known to play with captured prey after they have satisfied their necessary daily intake. In the book Animal Minds, the Author Donald Griffin describes an observation of a six-month old red fox who extensively appeared to release a captured shrew intentionally and return it to the vicinity of its burrow. This fox had caught and immediately eaten one mouse, then caught another with which he “played vigorously for several minutes”. After it had been killed the fox carried it some distance and cached it.

Although this showed he was no longer hungry, he soon captured a shrew, which he carried some distance to an open roadway where he began to play with it. The fox’s behaviour was also described as leaping around, dancing about the shrew who runs over to one side of the road before the fox herds it back to the center. After 45 seconds of playing with the animal, the fox does an extraordinary thing. He picks the shrew up in his mouth, walks back down the slope to where he captured the prey and then with a toss of his head spits the shrew out directly at a small burrow. Perhaps there is the possibility that animals cache their food in order for future perusal, instead of trying to eat everything in sight. ³

Humans could learn a thing or two about greed, or the lack of it from these creatures. The symbiotic nature of the environment would definitely have a role to play in explaining such phenomena and we could take our cues from the animal kingdom in a bid to stave off world hunger perhaps?

More information on Killer Whales:

• http://www.seaworld.org/animal-info/Animal-bytes/animalia/eumetazoa/coelomates/deuterostomes/chordata/craniata/mammalia/cetacea/killer-whale.htm

• http://www.seaworld.org/animal-info/info-books/killer-whale/diet.htm

Videos On Killer Whales hunting Prey:

• http://odeo.com/episodes/23491062-Animals-Attack-Killer-Whale-vs-Sea-Lion

• http://news.bbc.co.uk/2/hi/science/nature/7940208.stm

^References

(http://www.flickr.com/photos/magw21/126462740/)

Just like us human beings, the Squirrel World has its own “Facebook” social network! Who would have thought that we’d have so much in common with squirrels, after all?

According to Theodore Manno, a biologist at Auburn University in Alabama, “Squirrels with many connections tend to befriend squirrels that are like them; squirrels without many connections tend to befriend squirrels like them as well.” This is parallel to the way human beings behave, whereby we visit the Facebook profiles of people whom we are either friends with or interested in, and such friends are usually similar to us in terms of social networks.

However, one stark difference between human and squirrel social networks is the degree that they are “separated” by. People appear to be “separated” by five or six degrees, whereas for squirrels, it only takes three connections for one member of a population to get to any other. The existence of such social networks amongst squirrels then highlights the complexities of animal behaviour.

Manno postulates that most of the connections were between mating squirrels and their families, but friendship, too, exists in the squirrel world. This view is in line with Dunford’s (1977) findings, which put forths the trend of the retention of offspring within the mother’s territory, as well as the trend of dominant males defending one or more females, their offsprings and their combined home range. Squirrels thus become “friends” if they interact amicably just by meeting each other in the general course of things, due to them having preferred companionships.

It is also interesting to note that if more than 10% of the important members of the squirrel network were to be removed, the network would fragment, thereby becoming vulnerable to collapse. “Importance” in a squirrel colony generally refers to “adult males that are putting out feelers for sex opportunities, or adult females that are experienced at mating and want to have their choice of a bunch of males, as Manno discovered from his experiments.This effect is not confined to the squirrel population, though. Populations of other social animals, such as that of primates, fish, killer whales, and dolphins, could also experience comparable collapses when disrupted.

The study of social networks of animals brings out the different relationships of individuals with others, and this is imperative as it is often an aspect that we fail to take into consideration, due to our assumption that animal relationships are more or less homogeneous. Blumstein, an associate professor of ecology and evolutionary biology at the University of California at Los Angeles, also acknowledges the importance of studying social networks, as diseases might be better controlled in animal societies if key networkers, which might become “super-spreaders,” are removed, perhaps temporarily.

So, the next time you plan on befriending someone, think twice before expanding your social network!

Example of Squirrel Social Network

References:

“Squirrels Network Like Facebook Friends” by Jennifer Viegas, Discovery News, 21 February 2008, http://dsc.discovery.com/news/2008/03/21/squirrel-social-network.html

Dunford, Christopher, 1977. Social system of round-tailed ground squirrels. Animal Behaviour, Vol. 25(4), 885-906.

Manno, Theodore G., 2008. Social networking in the Columbian ground squirrel, Spermophilus columbianus. Animal Behaviour, Vol. 75(4), 1221-1228.

Blacktip Reef Shark Sea Life Centre München, by Wolfgang Kopp

(http://www.flickr.com/photos/96922481@N00/146333555/)

So you think DNA testing can only be used on humans? Think again. Scientists have used DNA testing once again to verify shark parthenogenesis—the process that allows females of some species to produce offspring without sperm.

Tidbit, a female shark, which died recently, was found to be pregnant despite being held in captivity in a no-males tank, way before sexual maturity. It seemed like a case of immaculate conception (very much in the realm of Christian saints huh?) Scientist Demian Chapman and his colleagues generated a DNA fingerprint for the mother shark and her pup fetus with a procedure identical to a human paternity test. Ordinarily, a shark’s DNA contains some genetic material from its mother and some from its father. Tidbit’s pup, however, was not ordinary.

“Every part of the fingerprint of the embryo comes from the mother,” Chapman said. “In other words, there is no genetic material from a father.”

However, sadly for Tidbit, the birth may have been a cause for her premature death. The scientists have not ruled out the possibility that increased stress from the abnormal pregnancy contributed to Tidbit dying at such a young age.

This is no isolated case though. Parthenogenesis has been documented in all major jawed vertebrate lineages except mammals and cartilaginous fishes. In a widely publicized case that occurred on 14 December 2001, one of the three captive adult female bonnethead sharks (Sphyrna tiburo, family: Sphyrnidae (hammerhead sharks)) gave birth to a normally developed, live female pup which was apparently later killed by another fish in the aquarium.

Great hammerhead shark (Sphyrna mokarran) by echeng

(http://www.flickr.com/photos/echeng/303369170/)

This birth is significant because the well-documented capture history of these sharks is inconsistent with sperm storage by the mother as the probable explanation. All three-candidate mothers had been held in the absence of males for 3 years, since they were wild caught in the Florida Keys as immature animals less than 1 year old. At least 2 years away from the age of first maturity, it is improbable that they were capable of sexual activity and sperm storage prior to capture.

Perhaps the animal kingdom is not too far away from being entirely reliant on females alone for reproduction! That should please some of the feminists among us.

References:

“Shark Virgin Birth Confirmed” by Sara Goudarzi, National Geographic News, 10 October 2008, http://news.nationalgeographic.com/news/2008/10/081010-shark-virgin-birth-2.html

Virgin Birth in a Hammerhead Shark, Demian D Chapman,^1† Mahmood S Shivji,¹ Ed Louis,² Julie Sommer,² Hugh Fletcher,³ and Paulo A Prodöhl^3,*Biology Letter 2007 August 22; 3(4): 425–427.

The Great White

        Thanks to the classic movie “Jaws” by Stephen Spielberg, the legendary Great White shark has enjoyed the reputation of being one of the world’s most fearsome man-eating machines. Fortunately, only half of that is true. While they have evolved to become a ruthless and efficient predator, the taste of human meant do not particularly appeal to them. Seals, sea lions and smaller sharks (yes, it is cannibalistic) are much preferred.

        To be able to rule supreme over the oceans means that this monster of a fish has developed killer instincts which give it an unfair advantage over their prey. Powerfully built, it can travel up to speeds of 24 km/h. It has an amazing additional sensory adaptation called the Ampullae of Lorenzini, which serves as a radar to detect the electromagnetic fields that other fish emanate. The 300 or more serrated teeth that line the jaws of the Great White allow for easy tearing of the prey’s flesh. As though these were not enough, it has an excellent sense of smell and has eyes which adapt very quickly to darkness.

        The manner in which the Great White hunts is interestingly, rather unorthodox. Rather than track its prey near the surface with its dorsal fin slicing through the water a la Jaws, they strike like a torpedo from below. Using their speed and strength, they charge and ram their unsuspecting preys at the surface. At the same time, they take a “test-bite” and return to feed on the wounded victim or carcass. They often use this method to satisfy their curiousity about their environment as well. Check out the video clip from the documentary “Planet Earth” to see this beautiful beast in motion.

Attack of the Great White – Planet Earth

        Ironically, it is this behaviour that most often allows humans to escape with their lives. Although badly wounded, they are usually able to reach aid in time. The reason why the Great Whites attack humans is only because humans resemble their natural prey – the seal, when swimming or surfing.

        Sadly though, despite its sheer strength and raw power, these ancient creatures have no response toward human cruelty and greed. Often killed because of the unwarranted fear that has become associated with it, or for human consumption, their numbers are gradually but surely dwindling. It’s time to raise awareness and knowledge about this awesome animal for it to remain the king of the ocean for years to come.

References:

www.nationalgeographic.com, Great White Shark: Carcharodon carharias,  (Assessed 10th April 2009).

www.marinebio.org, Carcharodon carharias, Great White Shark, (Assessed 10th April 2009).

http://serendip.brynmawr.edu/biology/b103/f00/web1/mccabe.html,  McCabe, Megan, “Sharks: Killing Machines?”, (Assessed 10th April 2009)

Treichel, Joan A, “Demystifying the Shark”, Science News, Vol. 110, No. 10 (Sep. 4, 1976), pp. 154-156.

 Images from:

www.cartoonstock.com

www.paranormalknowledge.com

Video from:

http://www.youtube.com/watch?v=5ZPhQewYf3c

Mind control is a word that is not usually associated with the real world. What comes to mind when this word is mentioned are images from horror movies. However, in actual fact, the manipulation of the mind for the benefit of self is not that far fetched after all! There have been recorded instances of animals that appeared to have the ability to control the behaviour of others through parasitism.

Parasitism refers to a type of relationship between two organisms, in which one receives benefit from the other at the expense of the other organism. Some examples of well known parasites are the tapeworms and fleas.

Tapeworm

While some parasites induce pain, spread diseases and cause general deterioration of the host’s health, there are some parasites that do far more than merely affecting the physical being of the host.

wasp eggs deposited on caterpillar

The trematode parasite, Microphallus sp. was found to affect the behaviour of infected snails radically. The snails are the intermediate host for the parasite while birds are the eventual host. It was found that snails that were infected by the parasite were more prone to linger in open areas, where they were more noticeable by its predators. This bizzare behaviour greatly increases the possibility of the snails being spotted and consumed by birds. Once the parasitized snail is consumed by a bird, the parasite is then able to complete its developmental cycle in the bird’s body. Hence, through the modification of the behaviour of the snail, the parasite significantly increased its chances of completing its development (Levri, 1999).

Another example of such mind control actions of parasites include how wasps affect the behaviour of orb weaving spiders. The wasp Hymenoepimecis argyraphaga parasitizes on its host, the orb-weaving spider Plesiometa argyra by laying eggs on the abdomen of the spider. The spider is then able to carry out its normal daily function and appeared unaffected by the infection while the larva of the wasp feeds on the spider through small holes made on the spider’s abdomen. However, on the night before the larva kills off its host, the spider is induced to make a cocoon web that is able to support the cocoon of the larva, instead of its usual orb shaped web. Upon completion of this task, the spider is then killed and becomes food for the growing larva (Eberhard, 2001).

Normal orbweb vs Web spun by parasitized spider

Researchers are currently looking into the mechanism behind such phenomenon and if successful, this could translate into highly effective pest control measures.

References

Eberhard, W.G. (2001). Under the influence: Webs and building behaviour of Plesiometa argyra (Araneae: Tetragnathidae) when parasitized by Hymenoepimecis argyraphaga (Hymenoptera: Ichneumonidae). Journal of Arachnology 29, 354-366.

Levri, E.P. (1999). Parasite-induced change in host behaviour of a freshwater snail: parasitic manipulation or byproduct of infection? Behavioural Ecology 10, 234-241.