Species are pelagic in that they live and feed upon surface-floating hosts, the colonial hydroids such as Physalia (bluebottles), Porpita and Velella. They float upside-down in the ocean utilizing a gas bubble in their stomach for buoyancy which is usually visible on the ventral (uppermost in this case) surface of the body. The oral tentacles and rhinophores are much diminished compared to other aeolids. The cerata are arranged in rows on the ends of 3 or 4 lateral lobes down each side of the body like the fingers of a hand. These rows can be arranged in a single plane or as multiple rows. The anterior lobes are so large they give the animal a T-shaped appearance. The cerata, as with most aeolids, possess nematocysts stored in the tip that are used in defence having been obtained from their prey during feeding. They are able to “swim” by rowing the lateral lobes and by bending the body up and down. There are no special gill structures. Across the family they have a worldwide distribution in the tropical and warm temperate zones due to the floating lifestyle and are often found washed up on ocean beaches together with their prey.