Zoologger: Baby lobster with a taste for jellyfish surfing

Zoologger is our weekly column highlighting extraordinary animals – and occasionally other organisms – from around the world Species: Ibacus novemdentatus Habitat: Western Pacific and Indian Oceans It's not every day you see a crustacean surfing a jellyfish. Adapted perfectly for hiding on the sandy ocean floor, the adult animal looks like it has been squashed flat by a hard object in early life. However, this couldn't be further from the truth. Young lobsters spend their first weeks in the softest surroundings imaginable – floating on a pillow of jelly.

Well, jellyfish to be precise. Smooth fan lobster larvae are underwater surfers. They latch onto their jellyfish host and then kick back and relax while it does all the hard work. And if a free transport service was not enough, the work-shy youths also treat the hapless animal as their own private buffet. It's first class travel. Easy rider "By using jellyfish as food and a vehicle they can eat and rest at the same time," says Michiya Kamio from the Tokyo University of Marine Science and Technology in Japan. "It may be lazy but it's also very smart."

Free room and board is an attractive proposition but jellyfish don't make the easiest bedfellows. First there is the thicket of poisonous tentacles to contend with. Evolution has been kind though, giving lobster larvae an immunity to toxins which allows them to quickly chomp through this first line of jellyfish defence. Despite now being armless, the jellyfish has another trick up its sleeve. It secretes a thick mucus from its skin that covers the hitchhiker from head to toe. This sticky goo prevents the lobster from breathing properly and is a feast for bacteria. In this dirty state, the larvae itself risks becoming the dish of the day. With their lives at stake, young lobsters spend half their time grooming themselves. This got Kamio and his team wondering how the larvae manage such a time-consuming beauty regime. Clean living They focused on one of its elongated appendages, which exists in a much stubbier form in other species to help with feeding.

Kamio suspected this limb had evolved into a specialised windscreen wiper whose sole job was to keep the growing lobster spotless. He was right. When covered in a substance that mimicked the foul jellyfish secretion, lobsters used this brush to fastidiously clean every nook and cranny. Animals who had this tool immobilised with super glue came out of the lab tank filthy. Without this unique grooming device, which is long enough to clean its entire body, jellyfish surfing would be almost impossible, says Kamio.

As it is, larvae can dine at their leisure, taking anywhere from a few hours to several days to polish off their ride. At which point, the youngster heads off in search of its next mobile meal. Journal reference: Journal of Experimental Marine Biology and Ecology , DOI: 10.1016/j.jembe.2014.11.008 If you would like to reuse any content from New Scientist, either in print or online, please contact the syndication department first for permission. New Scientist does not own rights to photos, but there are a variety of licensing options available for use of articles and graphics we own the copyright to.