Wingsquid flies in the face of old theories

A new wingsquid species discovered from the depths of the Spec Pacific may force evolutionary biologists to reevaluate their views on baleen squid evolution.

The new species has been named Anomaloteuthis improbabilis and assigned to its own genus whithin Cthulidae, a clade of primitive balaenateuthid cephalopods thought to resemble the ancestors of the baleen squids.

This species is however unlike any other cthulid discovered so far. The genus name Anomaloteuthis stands for anomalous squid but is also an allusion to the Cambrian predator Anomalocaris, which shared some features with the newly discovered cephalopod. "This does not mean they are related any more than sharks and dolphins are," said Specworld cephalopod expert Rauno Turisas, a member of the team responsible for the discovery, "It's convergent evolution."

The unique anatomy of the animal came as a suprise to the team. "Anomaloteuthis has this row of flippers starting from the rim of the mantle, which isn't seen in any other balaenateuths," Turisas said. "You'd really expect a structure like this to be an unbroken fin instead of split into several flippers." Most cthulids indeed have just two large flippers that form from the rim of the mantle. Turisas has had the opportunity to observe the ontogeny of Anomaloteuthis, and found the origin of its multiple flippers.

"Anomaloteuthis larvae look like normal wingsquids for the first weeks of their life. After that they grow a new pair of flippers just next to the first, then another, and another, until they have six pairs of them," he said. "They're really something else."

Anomaloteuths use their flippers to swim either forwards or backwards, somewhat akin to Arel [Home-Earth] cuttlefish. "They aren't built for speed," said Penelope Gilman, who has studied Anomaloteuthis behavior for the past year, "but they are perhaps the most maneuverable cephalopods in Spec." Anomaloteuths use this maneuverability to silently sneak up on their prey, which they catch with special tentacles that lack suction cups but ending in finger-like extensions.

While Anomaloteuthis may externally appear to differ from other wingsquids only by its unusual flippers, there are more differences in internal anatomy. "Anomaloteuthis has a complex nervous system closer to that of baleen squids than other cthulids. It can also change its color very rapidly," Gilman said. Anomaloteuthis has also almost completely lost its internal shell.

"Anomaloteuthis is a curious combination of primitive and derived characteristics," says specevolutionist Sam Ling. "It's certainly going to cause some headaches back on Home-Earth." According to the current theory the four-flippered baleen squids evolved from a two-flippered animal resembling the mantasquids. The huge "wings" formed from the mantle would at some point have split in two forming the two pairs seen in modern baleen squids.

There have however been people suggesting that the slowly plodding mantasquids and actively hunting baleen squids evolved baleen feeding indepenently from each other. Now some see Anomaloteuthis as an indirect proof of this.

"Despite its primitive features, the feeding technique of Anomaloteuthis admittedly has some similarities with that of the imperial baleen squid," says Ling. Still she doesn't believe anomaloteuths are closely related to the ancestors of baleen squids. "It appears to me that we're looking at a case of convergent evolution rather than a living fossil. Anomaloteuthis is just doing what baleen squids did some thirty million years ago."

from Spexploration Weekly