Filter Feeding for Fun and Profit

Another Lens on Life post by Chuck Kopczak, PhD

A cluster of translucent tube-shaped tunicates, speckled with gold-colored flecks
Chuck Kopczak, PhD

A cluster of tunic-band tunicates (Euherdmania claviformis) at Willows West Wall on Santa Cruz Island.

Today’s photo was taken at Santa Cruz Island off the coast of California at a dive site known as Willows West Wall with a Canon EF100 mm f/2.8 Macro USM lens on a Canon EOS 5D Mk. III in an Ikelite underwater housing. Lighting was provided by an Ikelite DS161 strobe set on eTTL exposure. The exposure was set at 1/180 sec. at f/11 and ISO 400.

The odd-looking creatures in today’s photo are known as tunicates, an exclusively marine group of animals that take many forms. Those in this photo are known as the tunic band tunicate (Euherdmania claviformis) and are found along the Pacific Coast of North America from Central California south to San Diego.

Like all tunicates, this species makes a living by filtering its food from the passing water. Like this species, some tunicates are sessile, living attached to a surface, while others are pelagic, and float with the currents while filtering dinner.

Tunicates belong to a group that is more closely related to all vertebrate animals, humans included, than any invertebrate species found in the oceans. It’s hard to believe that this strange sack-like creature is a very distant relative of ours. But there you have it.