Meet the squidworm: half-worm, half-squid… er, actually all-worm

By Ed Yong | November 23, 2010 7:00 pm

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Some scientific discoveries are exciting because they have the potential to save lives and revolutionise the way we live. Others are exciting because they fundamentally change the way we view ourselves and the world around us. And others are exciting because they involve a worm with tentacles on its head.

This is the third kind of discovery.

The squidworm looks like a fusion animal, half-squid and half-worm. In fact, it’s all worm, a member of the group that includes familiar earthworms and leeches. It just happens to have ten long tentacles on its head.

The tentacles are elastic and extendable, and they can be longer than the squidworm’s ten-centimetre body. Two of them – the yellower ones – are used for feeding. The other eight are used to breathe, or possibly to feel its way around. Its head also carries two feathery, brush-like structures called ‘nuchal organs’ that act like a nose, picking up chemical smells in the water.

It’s formal name – Teuthidodrilus samae – means squidworm of the Sama, the people who live in the local Philippine islands. “The name was suggested by the Philippino collaborators that took part in the expedition that discovered the animal,“ says Karen Osborn from the Scripps Institution of Oceanography, who first discovered the worm in 2007. Using remote-controlled submarines, Osborn explored the depths of the western Celebes Sea off the eastern coast of Borneo.

Osborn announced the squidworm’s existence last year (although it hadn’t been formally described then). The animal made its debut alongside six other species of deep-sea worms that it’s closely related to. Four of these are ‘bomber’worms – they release glowing fluid-filled capsules from their heads, probably as decoys to draw the attention of predators.

The squidworm has no such defence and it doesn’t seem to be a very strong swimmer either. Like the bomber worms, its flanks are lined by rows of bristled oars that beat in hypnotic waves. But unlike the bombers, the squidworm has a more leisurely pace. It’s certainly no predator; instead, Osborn thinks that it filters food from the bits of matter that sink down from the upper ocean.

Over seven dives, Osborn found 17 of these distinctive creatures and she expects to find many more. She thinks it’s probably fairly common and other related species will soon be discovered. The fact that such a striking animal has only just been discovered says a lot about our ignorance of the deep sea.

The squidworm lives in one of the richest but most mysterious layers – the demersal zone, just above the ocean floor. It’s the largest habitat on Earth, and a haven for undiscovered life. Here, animals can easily evade collection devices towed along the seafloor, while staying under the reach of mid-water nets dragged overhead. To appreciate the richness of life in these waters, you need special submersibles like the ones that Osborn used, which can move about easily and collect local animals without damaging their frail bodies. Who knows what else the subs will discover?

Reference: Biology Letters

Related: Marine worms release glowing “bombs” to fool predators
If the citation link isn’t working, read why here

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CATEGORIZED UNDER: Animals, Invertebrates
MORE ABOUT: squidworm, worm

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