Giant ‘alien-like’ shrimp stumps scientists

It's not every day that an ordinary fishing trip turns into an encounter with a colossal alien-like sea creature, but that's what has just happened to one fisherman.

Steve Bargeron was fishing off a dock, last week when a couple fishing nearby pulled up what Bargeron jokingly described as an "alien creature."

The couple wasn't interested in keeping the strange, lobster-like animal, which was flopping its tail wildly, Bargeron told Live Science.

So the curious fisherman took a few photos and then threw the critter back into the water.

But Bargeron's close encounter with this strange-looking specimen isn't really that strange after all, according to Roy Caldwell, a professor of integrative biology at the University of California, Berkeley.

Caldwell said he saw the photos online and instantly recognized the creature as a mantis shrimp, or stomatopod, a marine crustacean commonly found in the waters off Florida.

Stomatopods are easily identified by their prominent claws, which, depending on the species, they use to either stab or smash prey, Caldwell said.

"Praying mantis have similar [appendages], which is why these creatures are sometimes called a 'mantis shrimp'" Caldwell said.

The specimen caught in Florida belongs to a species of Lysiosquilla, according to Caldwell.

Like other members of its species, the creature has three pairs of walking legs and a large, articulated abdomen, Caldwell noted.

"This particular group — Lysiosquillidae — are almost all banded yellow and black across their bodies," Caldwell said. They can live for 30 years and can grow to be 30 centimetres long, he added.

But this specimen doesn't belong to the largest of stomatopod species, according to the biologist.

That distinction goes to Lysiosquillina maculata, which inhabit the Pacific Ocean from Hawaii to east Africa. Caldwell said the largest known members of the species were 38 cm long.

Even so, Bargeron said the mantis shrimp he found recently was significantly bigger than the largest-known Lysiosquillina maculata at 46 cm long.

However, the fisherman pointed out that he didn't have a tape measure handy to properly record the size of the catch.

Caldwell, who said he's been studying stomatopods for 50 years, said a near-half-metre catch is unlikely.

Photos, he pointed out, can sometimes be deceiving.

He also noted that, with its claws extended, a stomatopod tends to look much longer than it really is. The standard for measuring the creatures is from the tip of the eye to the end of the tail — claws not included.

But the sighting of a mantis shrimp is still something to celebrate. Fishermen and other water-loving folks don't often get to see these strange-looking animals, because they live in burrows on the seafloor and seldom come out.

In fact, female mantis shrimp may never leave their burrows during their lifetime, Caldwell said.

Morning news break – September 8