Bryozoans are small colonial animals (typically about 0.5 millimeters), which have a crown of tentacles (lophophore) with which they generate a water-sucking current, which allows them to capture small prey formed mostly by plankton. To ensure the catches, the tentacles that make up the lophophore secrete a sticky substance, which favors the capture of plankton. Approximately 5,700 species have been described, most of which are marine, although there are a few exceptions that live in freshwater environments. Their feeding habits, to a certain extent, condition the habitats in which we can find Bryozoans, preferring waters that are not very turbulent, with little current and lack of pollution.
As they are colonial animals, we will find colonies in which the individuals (zooids) present a certain degree of specialization for certain functions, such as defensive, cleaning or reproductive functions. These specialized zooids only fulfill their function and are not capable of capturing food or excreting waste.
In relation to the reproduction of Bryozoans, chronologically, zooids act first as male specimens and then as female specimens. However, in a colony, there will always be zooids that are in the male state and others in the female state. Reproductive zooids release the gametes into the water, where fertilization occurs and larvae are generated. Although this mechanism of reproduction is the main one, there are certain species in which female zooids capture the male gametes that have been released into the water column, to fertilize their eggs internally.
Bryozoans are part of the diet of many species, among which we find various Nudibranchs, fish, Echinoderms and Crustaceans. They are therefore a fundamental part of the food chain, and their presence is indicative of the high quality of the water in which they are found.