Tuesday, July 3, 2007

Guppies of the Amazon

Some of us may have been seated in a dark theater in 1978, silently watching as the two hikers onscreen enjoy a cooling splash in that inviting pool. Within minutes all that could be seen was blood, lots of blood and of course, the "no trespassing" sign they had ignored.

That movie, Piranha, a horror film made for a reported $660,000 and followed in 1981 by Piranha II: The Spawning, cemented the reputation of the red-bellied piranha's deadly behavior. That reputation seems to have begun here in 1913, when president Teddy Roosevelt upon encountering them on a trip to Brazil, wrote they are "the most ferocious fish in the world."

According to new research though, they are far from that fierce. Professor Anne Magurran , a St Andrews University biologist has published a Royal Society paper with Brazilian scientist Dr Helder Queiroz from their 12 years of studies in the Mamiraua area of the Amazon. They decided to find out why the piranhas congregated in large shoals and tested their theory that this behavior allowed them to kill much larger animals in a swarming attack.

"That's what we thought when we started to do it and we looked for behavior consistant with co-operation, but we realized that primarily it was for defense and they are not that different from other fish species. They like to school when there are more predators around," Prof Magurran stated.

They are more worried about being eaten by larger fish, caimen, cormorants and fresh-water dolphins than using their ferocious teeth on prey. There have been no confirmed deaths from piranhas of humans probably because we tend to not look like the waterfleas, invertebrates, crabs, shrimp, small fish and various fruits and vegetable matter they usually dine on. There is no doubt that they can inflict a nasty bite but they tend to do that only in defense.

Piranha are so incredibly shy and afraid of being eaten that they began to hyperventilate when people approached their observation tank too closely. That's correct, hyperventelate. The ferocious fish that slashed their way through the Piranha movies, reduced whole cows to dog bones in literature and made Spectre agent No 11, Helga Brandt, their own sushi meal in "007's You Only Live Twice" are afraid of people. Fortunately, a screen installed around their tank stopped the gulping and flared, flapping gills on the fish. I don't care how docile and shy Prof Magurran says they are, I am not going to be the research assistant sticking my arm into a tank of piranha to hold little fish-sized bags over their mouths.

"It turns out their reputation is not really deserved and they are a little more gentle than most people think," said Magurran, who incidently also studies guppies off the coast of Trinidad.

Now that the word is out on the "ferocious" piranhas, I think I will have to put aside my idea of joining the Piranha Club.

1 comment:

Karen said...

I didn't even know there WAS a movie called "Pirhana". Of course.... I was born in '80....