San Diego County, California, US
A pair of Atkinson's Okenia (Okenia atkinsonorum) on the bryozoan Pleurotoichus clathratus
Night low tide on the city dock (-5 ft), on limstone riprap.
The Bryozoa, also known as Polyzoa, Ectoprocta or commonly as moss animals, are a phylum of aquatic invertebrate animals. Typically about 0.5 millimetres (0.020 in) long, they are filter feeders that sieve food particles out of the water using a retractable lophophore, a "crown" of tentacles lined with cilia. Most marine species live in tropical waters, but a few occur in oceanic trenches, and others are found in polar waters. One class lives only in a variety...