Weird Gramma
Previous Editions

An giant larvacean’s abandoned “sinker,” on its way for recycling on the sea floor.

Photo: Science Magazine/Monterey Bay Aquarium Research Institute
Giant Larvaceans
An active “house” occupied by the giant larvacean Bathochordaeus off Monterey Bay, California.
Photo: Science Magazine/Monterey Bay Aquarium Research Institute

Download Audio Version
Howdy, Weird Gramma here with “WeirdFins,” all about strange stuff in the sea, and brought to you by the National Oceanic and Atmospheric Administration. And how’s this for strange: a critter that spins a new web of sticky mucus every day and lives inside it! This jelly web looks like a big cloud of snot, and the animal that lives inside it is called a larvacean.

Larvaceans are tunicates, animals with a primitive spinal cord but no real backbone. They live in the open ocean, and their floating balloons are really big filters for feeding. The tadpole-shaped larvacean inside pumps water, plankton, and suspended debris into the web by beating its tail. Even giant larvaceans are only about the size of your little finger, but their houses are sometimes more than 3 feet in diameter, longer than a yardstick!

The reason some larvaceans build a new house every day is that that after filtering all kinds of gunk, the web gets clogged with debris. So the critter just throws its house away and builds a new one, and the old web sinks to the sea bottom like a collapsing parachute. Wouldn’t you like to just throw your messy bedroom away and get a new one every day? But these mucus sacs are important to a healthy ocean. For a long time, scientists wondered how deep-sea critters could get enough food since most ocean plants and animals are at the surface. What researchers at t he Monterey Bay Aquarium Research Institute found was that larvaceans’ discarded houses, called sinkers, are really a treasury of food particles for all that life on the sea floor. You’ll probably never see the house of giant larvacean in person--they’re so fragile, they break apart before they can be brought to the surface. But you can see pictures of a giant larvacean on the National Marine Fisheries Service WeirdFins link at

Home | About Us | Forms | Privacy Policy | Information Quality | Disclaimer | Contact Us | Feedback | Search