Giant larvaceans make their houses from mucus

THE deep sea is full of fantastical creatures. Gelatinous pink sea pigs shovel food with arms like tiny sea anemones. Delicate tripod fish stand on chopstick-like stilts. Barreleye fish have transparent heads that reveal all their internal workings. Giant larvaceans hold a well-deserved spot on this list of curiosities. Shaped like oversized sperm, with a head and wide tail, the faintly blue tunicates are just ten centimetres long. But their “houses”, ephemeral structures which the creatures build from a film-like mucus, can be up to a metre across.Larvaceans are a familiar sight to deep-ocean biologists. But, as Bruce Robison at the Monterey Bay Aquarium Research Institute (MBARI) told a conference in California earlier this month, it is only in the past few years that scientists have been able to study the animals in their native environment. Doing so has helped to answer the question of just why there is so much life on the floor of the deep ocean, where food was thought to be scarce.