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 http://dx.doi.org/10.1098/rsbl.2010.0923
Related: Marine worms release glowing “bombs” to fool predators
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Animals must wage a never-ending war against parasites, constantly evolving new ways of resisting these threats. Resistance comes in many forms, including genes that allow their owners to shrug off infections. But one species of fly has developed a far more radical solution – it has formed a partnership with a bacterium that lives in its body and defends it against a parasitic worm. So successful is this microscopic bodyguard that it’s spreading like wildfire across America’s besieged flies.
The fly Drosophila neotestacea is plagued by a nematode worm called Howardula. Around a quarter of adults are infected and they don’t fare well. The worm produces thousands of young in the body of its hapless host, and the little worms make their way into the outside world via the fly’s ovaries. Not only does this severely slash the fly’s lifespan, it also always sterilises her. But according to John Jaenike from the University of Rochester, the fly is fighting back.
During chase scenes, movie protagonists often make their getaway by releasing a decoy to cover their escape or distract their pursuer. But this tactic isn’t reserved for action heroes. Some deep-sea animals also evade their predators by releasing decoys – glowing ones.
Karen Osborn from the Scripps Institute of Oceanography has discovered seven new species of closely related marine worms (annelids) that use this trick. Four of these pack up to four pairs of “bombs” near their heads – simple, fluid-filled globes that the worms can detach at will. When released, the “bombs” give off an intense light that lasts for several seconds.
The worms were collected from the Pacific Ocean by remote-controlled submarines. Unfortunately, the small size of the bombs and the low resolution of the sub’s cameras meant that Osborn was never able to film the worms actually releasing their glowing payload in their natural environment (although she did capture some great videos; see bottom of post).
Nonetheless, the specimens she recovered would indeed launch one or two bombs, when they were prodded on any part of their body. If she prodded them further, they would release more bombs, until they ran out. The fact that some worms also carried much smaller globes suggests that they can regenerate them once their supply is exhausted.
Aesop’s fable “The Crow and the Pitcher” has been confirmed in a wonderful experiment. In the classic tale, a thirsty crow uses stones to raise the level of water in a pitcher until it rises within reach of its beak. This is no mere fiction – rooks, close relatives of crows, have the brains to actually do this.
The aptly named Chris Bird, along with Nathan Emery, gave four captive rooks (Cook, Fry, Connelly and Monroe) a chance to reach a small worm floating in a cylinder of water, with nothing but a small pile of stones sitting on the side. All of them solved the task, and Cook and Fry succeeded on their first attempt. They were savvy about the stones too, using exactly the right number to bring the water within reach and preferring larger stones over smaller ones.
The accomplishments of Bird’s rooks are even more impressive when you consider that rooks are not natural tool-users. Many of the corvids – crows, ravens and the like – are avid tool-users and the skills of the New Caledonian crow are rapidly becoming the stuff of popular science legend. But rooks are different – even though they too excel in laboratory tests (as Bird and Emery have previously shown), they hardly ever use tools in the wild. Rather than any special tool-using adaptations, their skills must stem from the sort of general intelligence that great apes are thought to possess.
More so than other members of the family, rooks are extremely opportunistic feeders, relying on a varied menu of seeds, insects, dead meat and rubbish. With such catholic tastes, food is never far from their beaks and they may have little need for specialised tricks involving tools. The same might be true for capuchin monkeys, which happily brandish tools in a lab but only ever use them in the wild when food is scarce. As Aesop’s fable moralised, “Necessity is the mother of invention.”