Sunday, November 14, 2010

Jabberjaw

I was looking through IUCN’s Species of the Day list and found something adorable. It fits the two facial features that define “cute”—big eyes and a short snout. Unlike most members of its group, it has been known to play by grabbing vegetation and trailing it behind itself as others give chase. It exhibits curiosity with man-made objects. It has a cutesy name that sounds like an embarrassing nickname.

It’s a six-foot long shark.

Image by Steven Campana

















Where the Porbeagle (Lamna nasus) gets its name no one is quite sure. The commonly cited combination of “porpoise” and “beagle” seems awkward to me, but there are a number of other etymological theories to pick from. They are built for speed, with crescent tails for powerful strokes, keels on the base of the tail for balance, and large gills for better efficiency. These adaptations help them chase after mackerel and other schooling fish to eat.

Their playful antics have been widely documented. They play tag using kelp, as mentioned above, as well as playing catch with driftwood. They will also poke at fishers’ balloon floats, and appear to be confused when they pop. The phrase “mindless killing machines” is so frequently thrown around with sharks, but the Porbeagle’s actions are causing a number of shark experts to question that concept. Other sharks (including the infamous Great White) have been described as “curious,” but they only have one tool with which to explore the world, and it’s filled with enough teeth to turn the object of their curiosity into mincemeat.

Despite their potential danger (see previous statement regarding teeth and mincemeat), the Porbeagle hardly attacks anyone - ever. The International Shark Attack File lists 5 total attacks, fatal and non-fatal, from the Porbeagle in 2003. Compare that to the Great White Shark with 244 fatal, unprovoked attacks. In fact, looking at the rest of the list, anything with fewer attacks than the Porbeagle either have no teeth, are impossible to find, or are too small to be a threat to humans. The infrequency of attacks may be due to the fact that “if the water is warm enough for you to be swimming, it is too warm for the porbeagle,” but it seems that this is a very docile shark.

One place the Porbeagle will fight ferociously is on a fishing line, and for good reason. Overfishing in the north Atlantic caused population crashes that devastated not only the shark, but the fishing industry that created the problem. These incidents have led to regulations to limit Porbeagle catch. Earlier this year, CITES set trade regulations in place to help save this playful, docile “mindless killing machine.”