Monday, July 02, 2007

Animal of the Week -- July 2, 2007

What a week for news!

On the plus side Tony Blair has gone, and although ballots were absent in the selection of his successor, and East Timor have held their first public democratic vote, and although the count is slow, the process looks good. On the downside, floods have ravaged the north of England and various US states, Wimbledon has barely started, the UK is on the highest state of terror alert after some deluded fanatics tried to car bomb London and Glasgow, and perhaps worst of all, to compound all the misery in the world that I have not been able to summarise in my brief introduction so far, the Spice Girls have reformed.

Thank god that news about animals tends to be more neutral, like that about this week's animal Pygocentrus nattereri (red-bellied piranha), in fact, this news is just about the best and most complete image overhaul sine Paris Hilton vowed to invest her time, money, and, er, intellect for good on her release from jail. For researchers now claim that piranhas are not the frenzied, blood thirsty, pack predators capable of stripping a cow carcass in minutes, but rather their shoaling behaviour is driven by cowardice in an attempt to avoid predation by river dolphins (AOTW, Feb 21, 2005: http://animal-of-the-week.blogspot.com/2005_02_01_archive.html), caimans, and the enormous fish that live in the amazon.

Now, I can't find out the exact species of piranha studies, but at red-bellied piranhas are some of the most aggressive, and certainly not the sort of fish immortalised in the "One, two, three, four, five, once I caught a fish alive" nursery rhyme, which would no doubt have a different ending if it were.* Most piranhas are vegetarian anyway, and the most aggressive ones, such as this and its close relatives, are likely to have been the subject of the study, if not, why bother?! Apparently even these typically only hang around in small shoals and prey on small fish, carrion, or bits of larger fish. According to the researchers, they only form large shoals when the waters recede and they are more prone to predation, and not for the purposes of hunting large animals and stripping the flesh from captured secret agents at the behest of Ernst Bloefeld.

Of course, you may have seen demonstrations of these voracious fish stripping a chicken carcass to bare bones in seconds, and they will do that, but only when kept in small tanks and deprived of food. Despite this image makeover for the piranhas, you still can't keep them in aquaria with smaller fish, they'd eat them.

*One two three four five
Once I caught a fish alive
Six seven eight nine ten
Then I let it go again
Why did you let it go?
Because it bit all my fingers off and I didn't have a choice.

Tak tak,

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2 Comments:

At 2:00 PM, Anonymous Scott K said...

The piranhas in question are indeed the red-bellied piranha Pygocentrus nattereri - I went to the Royal Society Exhibition where they were showing off this research. The factsheet they gave out named the species.

They also said that about half the diet was fruit and veg, and that the only time it was likely that a shoal would attack a living creature was during low-water droughts, when many fish were concentrated in small pools without much food - if you go swimming then, you're asking for trouble.

 
At 7:23 PM, Blogger animal_oftheweek said...

Cool, I wanted to go but was ill. Thanks for confirming the ID.

 

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