While many species found in the ocean are recognizable as being an animal or a plant, the ocean is filled with species that to the naked eye defy these standard classifications with which we are all familiar. As case in point is the subject of this week's photo - the lacy bryozoan (Phidolopora pacifica). Bryozoans are a unique phylum of invertebrate organisms that are colonial in nature.
A phylum is a classification in the scientific hierarchy of how we think all living species are related. In the hierarchy of life, phyla (the plural of phylum) rank just below kingdom, which separates species into groups like animals, plants, fungi, bacteria, etc. For comparison, if we considered all human beings on Earth as being grouped into the equivalent of a kingdom, then each person's country of origin would group them into approximately the equivalent of a phylum. But the differences between the kinds of animals found in different phyla are much, much greater than the differences found between people from different countries.
Bryozoans are in a phylum that groups together animal species that are colonial in nature; filter food from the water using a specialized crown of tentacles lined with tiny hairs called cilia; form limestone-like chambers in which individual colony members live; and are fixed to a single location on the bottom. It is the structure of these limestone-like chambers that gives the colonies of each species a unique, identifiable three-dimensional form. Each individual member of the colony has digestive and reproductive systems and a simple simple nervous system, but lack any advanced sensory organs. Individuals colony members in some species are further differentiated exclusively for colony protection, brooding of embryos, or attaching colonies to the substrate.
The lacy bryozoan pictured in this week's photo is found on rocky reefs from British Columbia, Canada, to South America. It can range in color from bright to pale orange with perforations in the hard, brittle structure of the colony. These perforations give rise to the common name of the species.
While often confused with animals with stinging cells like hydroids or corals, bryozoan feeding tentacles lack stinging cells. The tentacles are used to capture bacteria, phytoplankton, other small organisms and detritus suspended in the water.
This photo was taken with a Canon EF100mm f/2.8 macro lens on a Canon EOS 5D Mk III in and Ikelite underwater housing. Lighting was provided by two Ikelite DS-161 Substrobes in eTTL mode. The exposure was set to 1/90 sec at f/8.0 and ISO 100.