With his sail unfurled he is a pretty imposing little blenny. His dorsal fin is also used to attract a mate. He jerks in and out of his tube and flashes his big fin, hoping to get a female's attention. If she likes what she sees, the female will deposit a few eggs on the outside of his tube. He will guard the eggs from predators for several days until they hatch.
Blennies eat mainly zooplankton, including isopods and amphipods.
From Baja, California, south to Peru.