The northern clingfish is a common intertidal and shallow subtidal inhabitant of rocky areas from southeast Alaska to Baja California. It is one of several local fish that have suckers on their bellies.
Normally found under rocks or clinging to kelp, it uses its sucker to keep strong water movement from carrying it away. The sucker, formed from its pectoral and pelvic fins, also is used at low tide to hold some water close to the gills for breathing.
The clingfishs body is further modified by having a compressed head, tadpole-like body proportions and smooth skin.
The skin is dark, ranging from a gray to brown to red with a chain-like dark pattern. The fish commonly are about 3 inches long but can be as long as 6 inches.
While feeding on small limpets, chitons and other small molluscs, it uses its sucker as an anchor so the head and bottom teeth can be used to pry a limpet or chiton off a rock.
The northern clingfish can fall prey to a variety of animals that hunt among the rocks at high tide.
However, it also is at risk during low tide, when upland predators such as snakes and raccoons hunt among the boulders.
Reproduction occurs in the early spring, when eggs are deposited on the underside of rocks. The males remain to tend the egg masses. The larvae are planktonic.
David W. Jamison is a Boston Harbor resident and marine biologist.