LSM1303 Animal Behaviour Student Blog : predator

Trench Warfare !

SHINDERJEET KAUR — Fri, 21 Mar 2008 06:36:00 GMT

If you thought Trench Warfare was a military tactic of the French and Germans of the past, you might want to you might want to reassess this hasty conclusion. A species of ants, known as the Allomerus decemarticulatus employs a somewhat similar tactic to catch its prey. These ants are masters in taking cover in the ground and setting up the ideal trap which is extremely successful in luring insects of a much bigger size than themselves. To find out the details of their master “torture” plan and of how they deceive their unsuspecting victims, have a look at the links at the end of this short write-up and the images provided should help you better visualize this unique and indeed ingenious method of feeding. Here is a quick summary of their grand plan:

Using plant fibers and fungus, the ants engineer the perfect trap.
They leave holes in the trap, big enough to poke their heads through.
Its victim happens to land at this strategic spot.
It finds its legs or antennas, or anything that the ants can grab being pulled and torn from it. This causes the victim impairment or even death.
The ants in this colony, have earned themselves a meal and will carve out their winning which they will share amongst themselves.
Here’s a limiting factor to their tactic though, the victim’s legs, hands or antennas have to be able to fit into these holes to for the plan to be successful.

I find this article particularly interesting because it is relevant to the topic of cooperative hunting we saw in the Harris Hawks as discussed in lecture. Because these ants work in a colony, they are able to feed on such a large insect which would otherwise not be possible if they were to attempt this feat alone.In fact, there is no doubt that the prey they caught collectively could be a predator if not for this method of kill.Pretty interesting reversals of prey and predator !

Besides that, the articles also mention that these ants work in a hierarchy of which we encountered during lecture again. Apparently, the oldest ants in the colony will do the work of trap building. It must come from experience that they are chosen to carry out this critical task. Any loopholes will evidently result in a failed plan which the ants overcome with the division of labor.. The younger ants will learn from their elders and the tradition will then pass down the successive generations. Reminds us a little about the archer fish too with regards to learning the exact positing from which it should sprout water and get its prey !

In sum, these articles have highlighted both feeding and predatory behavior and the importance of hierarchy in ants.

Ants; traps; torture; prey; cooperative hunting; feeding; colony; hierarchy; division of labor; group30

References

Amazing Ants Ambush Prey from Foxholes

By Robert Roy Britt, LiveScience Senior Writer ,20 April 2005

http://www.livescience.com/animals/050420_ant_trap.html

Fierce ants build 'torture rack', 23 April 2005

http://news.bbc.co.uk/2/hi/science/nature/4472521.stm

"Torture Racks" Are First Known Traps Made by Ants, James Owen, 20 April 2005

http://news.nationalgeographic.com/news/2005/04/0420_050420_ant_trap.html

Prey vs. Predator - A No-holds-barred Title Match!

TAN SZE HUI VALERIE — Wed, 19 Mar 2008 17:29:00 GMT

In the red corner, spanning a wee 0.1 of an inch from tip to tip, the common cabbage aphid! Found world-wide, though more common in temperate regions; today's contender for the world light light light light light weight championship belt is armed to the teeth with... a soft body (too many beers, tsk tsk), long thin legs (wolf whistles) with two-jointed, two-clawed tarsi!!!

And in the blue corner, at four times the contender's size of 0.4 inch, our returning champion, Coccinella septempunctata a.k.a. the L~a~d~y B~i~r~d (and the crowd goes wild)! Dressed up in his crowd pleasing customary costume of black spotted red armour, this lean, mean, fightin’ machine is the natural enemy of today's upstart contender.

*ding ding ding* and Round One begins!!!

Back to the ring, WHAT do we see here? Who can believe their eyes?! Today’s contender, the wee little aphid, has turned tail and retreated to his corner; can’t say I blame him though. He's huddled trembling in the corner, with his BACK facing our champion… it has nowhere to run, and nowhere to hide. The ladybird is moving ever so much closer, closing the gap between them with every step. Poised to strike, the champion is almost upon the timid contender and.....BOOOOM!

What in the world has happened, the ring has exploded with a great big puff of smoke... and LOOK! There, in the center of the ring, the champion! OH MY GOD, he's not breathing, what did the aphid do?!

Read on to find out =p

http://www.sciencedaily.com/releases/2007/07/070711105844.htm

Survival Adaptations Score Board:

Prey 1 Predators 0

Adaptation of predators in increasing efficiency and success rates of catching their prey has been known far and wide, and often to the astonishment of many researchers. Sharks have adopted efficient and strength conserving prey searching movement patterns as they scour the vast expanse of the oceans, Cheetahs and other larger cats have learnt to observe herds of their prey, waiting patiently for that special individual that dares to stray away from the security of their family. However successful the predatory behavior and adaptations of the aggressor, the apparent prey is still rather prevalent in each and every habitat, suggesting that the prey too, perhaps has developed some clever behavioral patterns to outwit its predators and survive their dangerous encounters.

Siberian Jays featured in the following article; seem to have taken a leaf out of Sun Tzu’s “The Art of War” by learning their predator’s behavior. However, this as expected, is never enough. Hence, the Siberian Jays have built on this and created their own way of keeping themselves safe from harm, read on at

http://www.sciencedaily.com/releases/2008/01/080109100221.htm

Survival Adaptations Score Board:

Prey 2 Predators 0

And the score is out! The prey are the new champions! Better luck next time, predators!

References:

Imperial College London (2007, July 12). Aphids Make 'Chemical Weapons' To Fight Off Killer Ladybirds. ScienceDaily. Retrieved March 20, 2008, from http://www.sciencedaily.com /releases/2007/07/070711105844.htm

Uppsala University (2008, January 11). Some Birds Can Communicate About Behavior Of Predators. ScienceDaily. Retrieved March 20, 2008, from http://www.sciencedaily.com /releases/2008/01/080109100221.htm

Green Anaconda Devours The Spectacled Caiman Alligator!!! (Warning: Not for the faint-hearted)

CHUA CHING HOCK — Mon, 17 Mar 2008 19:16:00 GMT

Never thought that an adult Spectacled Caiman alligator (Caiman crocodilus) can be eaten alive by another predator? Well, think again!! Especially when you have this chap around:

(Image Source: http://animals.nationalgeographic.com/animals/reptiles/green-anaconda.html)

Introducing.... The Green Anaconda (Eunectes murinus) !!!

Well, I have always thought that anacondas' diet consist only of fishes, birds, rodents, mammals, and other small reptiles. But little did I expect to discover that this particular species, the Green Anaconda, actually feeds on full-grown Spectacled Caimans (which can grow up to 2.5m) as well!

Devouring a fellow fearsome predator? Wow.

My interest in inter-species conflict originally led me to stumble upon the incredible videos listed below. And upon closer research, I discovered that the Green Anaconda, located primarily in South America, is actually the largest snake in the world in terms of weight. They can grow up to 30 feet (9 meters) long, weigh 1,200 pounds (550 kilograms), and measure more than 12 inches (30 centimeters) in diameter.

Youtube Link:
http://www.youtube.com/watch?v=acVlIJeY9ws&feature=related

As illustrated in the video above, the Green Anaconda kills with power, not poison. By coiling its muscular body around its prey, the Green Anaconda can even crush the armoured Caiman until it can no longer breathe. This constriction tactic allows the Green Anaconda to take down other prey as large as adult capybaras (giant rodents), adult white-tailed deers, adult jaguars, and even humans of approximately 55kg or more.

At the same time, this brutal predator can be really covert and sleek in the water, with its dull colour and black blotches enhancing its camouflaging capabilities in the marshes and swamps. Its eyes and nasal openings are on top of its head, allowing it to wait and ambush its prey while remaining almost completely submerged.

Youtube Link:
http://www.youtube.com/watch?v=Xc06MVH6W98

Interestingly, while all the videos here highlight the Green Anaconda prevailing over the Spectacled Caiman, my research indicates that this is not always the case. In fact, renowned anaconda specialist Jesus Rivas once documented an intriguing event of the Spectacled Caiman preying on a green anaconda in return:

"On 25 of May 1996 we discovered a large caiman (>90 cm svl) firmly gripping the head of a radio-implanted female anaconda (494 cm TL, 29 kg), who in turn had wrapped herself around the caiman’s head and neck. After approximately 15 min the snake relaxed her coils, apparently losing the struggle with the caiman.

We interrupted the event to recover the transmitter when the snake stopped struggling. One of the teeth of the caiman had gone right through the skull and into the brain region, other tooth mark where present in the first fifth but did not look life threatening. The snake died two months later in captivity due to a generalized infection. As we had found this snake severely wounded from 2 months previous to being preyed on by the caiman, it is likely that she was not in top physical shape and this may have played some role in the attack."

Certainly, there appears to be a history of inter-species conflict between these two large predators. One possible reason could be due to the fact that both share very similar habitats in the seasonally flooded savannahs of South America and the Amazon Basin.

Youtube Link:
http://www.youtube.com/watch?v=KMwt_fEe3CY&feature=related
(Warning: Do not watch this if you just had a heavy meal.)

As seen in the fascinating video above, the Green Anaconda possesses jaws attached by pliable ligaments, which enables it to swallow the Caiman as a whole. Such a sizeable and yummy meal can allow it to go for weeks or even months without food.

At the same time, the Green Anaconda's unique adaptation and natural selection allow it to experience an incredible change in body size from birth to adulthood, as compared to other snakes. This explains how it can grow to such a massive bulk despite the occasional meal. Moreover, the role of nature has also dictated that baby Green Anacondas can almost immediately be able to swim and hunt once they are born. A top, ectothermic predator indeed.

Poor Caiman.

Finally, just to make you feel a little better, Green Anacondas are not known for being fond of attacking humans, despite their mythical reputation as man-eaters. Thankfully. =)

References:

BBC Science and Nature, Amazon Abyss (Apr 2005)
<http://www.bbc.co.uk/sn/tvradio/programmes/amazon/creatures.shtml> 16 Mar 2008

Isho, Fady D., AllExperts, Interspecies Conflict: Saltwater Crocodile vs Green Anaconda (26 Jan 2008)
<http://en.allexperts.com/q/Interspecies-Conflict-3754/2008/1/Saltwater-Crocodile-vs-Green.htm> 17 Mar 2008

Mayell, Hillary, National Geographic News, Anaconda Expert Wades Barefoot in Venezuela's Swamps (13 Mar 2003)
<http://news.nationalgeographic.com/news/2002/04/0430_020503_anacondaman.html> 16 Mar 2008

National Geographic, Green Anaconda
<http://animals.nationalgeographic.com/animals/reptiles/green-anaconda.html> 16 Mar 2008

Peach, Natasha, BBC Oxford, New Arrivals and Happy Feet (7 Jan 2008)
<http://www.bbc.co.uk/oxford/content/articles/2008/01/07/happy_feet_feature.shtml> 16 Mar 2008

Rivas, Jesus A., The Life History of the Green Anaconda (Eunectes murinus), with emphasis on its reproductive biology, Introduction (2000)
<www.anacondas.org/diss/intro.pdf> 17 Mar 2008

Rivas, Jesus A., Life history and conservation of the green anaconda - Eunectes murinus (2000)
<http://pages.prodigy.net/anaconda/research.htm> 16 Mar 2008

Rivas, Jesus A., Herpetological Review, Eunectes murinus: caiman predation (1999)
<http://pages.prodigy.net/anaconda/fight.htm> 16 Mar 2008

Rivas, Jesus A., Herpetological Review, Eunectes murinus: Juvenile predation (2001)
<http://pages.prodigy.net/anaconda/juvpred.htm> 16 Mar 2008

Vancouver Aquarium Marine Science Centre, AquaFacts: Green Anaconda - Eunectes murinus
<http://www.vanaqua.org/education/aquafacts/anaconda.html> 16 Mar 2008

Wikipedia, Anaconda (16 Mar 2008)
<http://en.wikipedia.org/wiki/Anaconda> 16 Mar 2008

Wikipedia, Green Anaconda (4 Mar 2008)
<http://en.wikipedia.org/wiki/Green_Anaconda> 16 Mar 2008

Wikipedia, Alligatoridae (10 Mar 2008)
<http://en.wikipedia.org/wiki/Caiman> 16 Mar 2008

Wikipedia, Spectacled Caiman (11 Mar 2008)
<http://en.wikipedia.org/wiki/Spectacled_Caiman> 16 Mar 2008