Baby lobsters don’t just play with their food. They ride it.
For a year or so before they morph into the bottom-crawling creatures that probably spring to mind when you hear the word “lobsters,” baby slipper lobsters drift in the open ocean, struggling to survive. Then along comes a jellyfish. What happens next is part buffet, part rodeo.
First, the baby lobster grabs onto the passing jellyfish, clambering up its body until it’s on top of the jellyfish’s head-like bell, gripping tight with its legs so that it “surfs” its gelatinous mount. And then the baby lobster chows down on the jellyfish—tentacles first—until it eats the creature out from under itself. It typically takes a baby lobster about three or four days to gobble up a jellyfish that’s 8 cm (3 inches) in diameter, says Kaori Wakabayashi, a marine science professor at Hiroshima University and Tokyo University of Marine Science and Technology.
What’s even more incredible is these are some highly venomous jellyfish we’re talking about here. Were you or I to nibble the tentacles of, say, a sea nettle, we’d be in for a world of pain (and maybe a trip to the hospital). So how do lobsterlets feast on these species without zapping their guts with toxins? It turns out that when smooth fan lobsters—a species of slipper lobsters—munch on a jellyfish, a filter in their mouth sucks liquid from the tentacles, digesting this nutritious fluid separately from the venom-packed cells. As for those usually deadly cells, the lobster’s digestive system somehow—scientists aren’t clear exactly how—bundles them up in a semi-permeable membrane that protects the lobster’s insides. (This is what Wakabayashi and her colleagues recently discovered (pdf) when they ran experiments on lobster larva feces.)
This isn’t just cool weird animal trick. Understanding how slipper lobsters feed on jellyfish could be a boon to Japanese fishing.
While slippers have long been sold in Asian seafood markets, they’re hard to raise—in part because they spend as long as a year as a tiny larva. And though we’ve figured out how to farm a few species in the slipper lobster family, their diet of bivalves makes feeding them labor intensive and expensive. Research led by Wakabayashi has found that three species of these lobsters could be raised on jellyfish alone.
There’s another potential upside, says Wakabayashi. Huge jellyfish blooms swarm the shores of Japan nearly every year now, thanks to environmental changes wrought by humans. These blooms can be disastrous for fishermen as the jellyfish’s blobby bodies clog their nets and sting the fish they catch. Or worse. For instance, in 2009, a bloom of giant jellyfish sank a 10-ton trawler when the crew tried to haul up its nets. The problem is, getting rid of jellyfish isn’t easy. Even if you kill them, as jellyfish corpses rot, they strip the water of oxygen, creating “dead zones” (paywall) in which most sea life struggles to survive. By collecting them as feed, Wakabayashi hopes to turn these terrible jellyfish blooms into a lobster boom instead.