My home is my castle… my boat … my fishing net

Appendicularians are wondrous creatures found everywhere in the world’s oceans. They build complex houses they use as a safe home, as a filtration device to capture food, and as their marine Winnebago. Using these houses, the animals can remove tiniest particles down to the size of viruses from the water and play an important role in the global carbon cycle, by facilitating the carbon efflux into the deep sea. We show, how the appendicularian house functions and how this function differs between species. We explain what is known about the production of the house as an intricately folded mucus rudiment by specialized cells of the animals’ skin. We also present the latest results from our ongoing studies of the evolution of the diversity of the 70 known species of appendicularians and discuss their crucial role for our understanding of the evolutionary transition from invertebrates to vertebrates.