The disposable mansion
In the midwater depths of the world's oceans, a tadpole-shaped animal builds and discards a new, elaborate house for itself on a continuous cycle. This creature is a larvacean, a type of tunicate. Despite their simple appearance, larvaceans are chordates, placing them among the closest living invertebrate relatives of vertebrates like humans. Species like Oikopleura dioica keep their tadpole-like shape throughout their lives. The "giant" larvacean, in the genus Bathochordaeus, is only about 10 centimeters long. Its disposable home, however, is more than a meter across.
The house is not built from collected materials but is secreted entirely from the animal's own body as mucus. The larvacean inflates this secreted blob into a filtering structure, a process that can take less than an hour. This "snot palace" has two main parts: a coarse outer filter to block large debris and a fine-meshed inner filter to concentrate food particles of the correct size. The animal lives inside this structure, beating its tail to pump vast amounts of seawater through the filters. A single giant larvacean can filter up to 76.2 liters per hour. When the filters become clogged, typically after just a few hours for smaller species, the larvacean abandons the entire structure and secretes a new one.