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Northern Staghorn Bryozoan          Heteropora pacifica

by Scott Boyd

A very common animal that divers swim by in our lush emerald waters is the Nothern Staghorn Bryzoan. This colonial invertebrate is often confused with a coral, and looks much like it’s tropical cousin with its yellow branching structure. In fact, it is a sessile animal found at depths from subtidal to about 90’ that ranges from Alaska to Central California.

The branching colonies that make up the Bryzoan grow to over 4 inches in height with a round cross section that is made up of many individual animals called zooids. Each zooid posses a simple nervous system along with a digestive track and reproductive systems. A typical zooid consists of a body within a calcareous chamber and an exposed tentacle crown. The tentacles are used to capture bacteria, plankton and other suspended detritus in the water. There are no advanced sensory organs present.

Bryzoans reproduce sexually, but grow their colonies by asexual budding. Many nudibranchs and sea stars feed upon the Northern Staghorn Bryzoan. The Phylum Bryzoan is referred to as the “Moss Animals”.

Staghorn Bryzoans are very common in Hood Canal and throughout Puget Sound, so next time you are cruising along the wall at Sund Rock, and you see what looks like a piece of yellow staghorn coral or sponge, now you’ll know it’s a colony of Northern Staghorn Bryzoans.