Big Sharks 1

The Plankton-Strainers

LIKE THE LARGEST whales, the largest fish in the world are not dangerous predator carnivores. They are plankton-strainers and plankton-eaters: the basking, whale and megamouth sharks. These sharks swim steadily through the water, mouths open, engulfing a soup of assorted copepods, krill and other zooplankton. More sea-monster stories come from this group of animals than from most other quarters, with the exception of carnivorous sharks and the giant squid. Early mariners can perhaps be forgiven for mistaking plankton-eating sharks for sea monsters; their sheer size, their open-mouthed swimming posture and their occasional “ferocity” when harpooned—dragging a boat underwater, for instance, or smashing it in an effort to escape—are formidable traits. Add to this the tendency for dead sharks (particularly basking sharks), perhaps partially eaten by carnivorous sharks and battered by waves, to break into rather large, monstrous pieces.

One of the great, long-running 19th-century monster stories describes just such a demi-beast from the Orkney Islands north of Scotland, initially thought to be a 55-foot-long (17 m) sea snake with a horse’s mane and six legs. The scientific paper published in 1811 created a new genus and species for this “seawater snake,” but scientists continued to argue about the monster’s true identity. Only 122 years later, in 1933, did a paper published by the Royal Scottish Museum (now the National Museum of Scotland) throw out the new species by showing that the monster was a decomposed basking shark. The “mane” of shark fin fibers, the extra “legs” of the shark’s claspers and the skeletal remains of the vertebral centrum were those of a basking shark. In fact, the animal must have broken into two pieces: one, the piece that was found, contained the cranium and backbone; the other contained the jaws, gill arches and flippers.