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.