New fiery Sea Slug described

Christine Dell'Amore

Marine biologist Jeff Goddard stumbled across the carnivorous three-centimetre creature - later dubbed Flabellina goddardi - while searching for another sea slug in Carpinteria State Park. The new sea slug species is formally described in the September 15 issue of the journal Proceedings of the California Academy of Sciences.

Not long afterward, in the lab, the hermaphroditic critter laid a lacy egg mass, which hatched into tiny, snail-like babies. "That was a treat," said Goddard, of the University of California, Santa Barbara's Marine Science Institute - though not necessarily a surprise.

Sea slugs are often transparent - "you can see the gonads through the body," for example - and Goddard knew the animal was expecting. The elaborate latticework of the egg mass is a "trick of arrangement" to make sure all the embryos get enough oxygen, he added.

"That whole string is packed with thousands of egg capsules." Finding a new slug "right there under our noses" is a reminder that "there are still many species, especially in the oceans - even ones in our backyard - that haven't been described," he said.

Plus, they're just plain stunning: "People are interested in butterflies and birds and brightly coloured animals," he said. "This is the marine equivalent of butterflies."

Sea Slug eggs

The 0.1-millimetre-long babies hatch into shelled larvae after about a week after the eggs are laid, Goddard said. The babies feed and grow on plankton in shallow waters off California for a month or two before they settle, metamorphose, and start eating adult food, in this case probably plant-like organisms called hydroids.

Smooth New Species

F. goddardi is notable for its orange-and-red-tipped back tentacles, smooth head tentacles, and a long and delicate tail while crawling, Goddard said. "Those are three characteristics that made me think, Ooh, this one's new." Generally, nudibranchs are brightly coloured, either to camouflage themselves or to warn away predators, he added. Virtually all sea slugs taste horrible to predators - that's why they don't need protective shells.

As for F. goddardi's vibrant palette, though, "without knowing more about its biology, I'd be hesitant to say whether it's camouflage or warning." Like other sea slugs, or nudibranchs, the new species Flabellina goddardi has a "tooth-studded ribbon" called a radula to catch prey, Goddard said.

But mysteriously, the new species has fewer teeth than other closely related sea slugs, he said.

- National Geographic