Barnaclebill Blenny, Hyposoblennius brevipinnis
The Barnaclebill Blenny, Hyposoblennius brevipinnis, whose Spanish common name is borracho vacilón, is a species in the family Blenniidae, the Combtooth Blennies, known as borrachos in Mexico. Globally, there are sixteen species in the genus Hyposoblennius, of which four are found in Mexican waters, one in the Atlantic and three in the Pacific.
The Barnaclebill Blenny is a smaller blenny with a shortened elongated body with a uniform depth throughout most of its body tapering significant at the rear into the tail. They are dark brown in color with very subtle colorations that include a horizontal row of circular tan patches just below the base of the dorsal fin, a second row of smaller patches or spots just below the first row, and a dark broad band that runs the length of the body slightly above the mid-line. They are off-white to yellow ventrally. The head has small brown spots and a prominent oblique band behind the eye. The eye has a dark edged whitish stripe on the upper and lower margins. The heads of breeding males are covered with red spots.
The Barnaclebill Blenny has a short and robust head with a very steep forehead profile and the outermost orbital cirri are unbranched but with one to four shorter cirri at the base. The mouth is small and opens at the front and is equipped with one row of teeth with blunt flattened tips on each jaw. The anal fin has two spines and fourteen rays, the caudal fin is rounded, and the dorsal fin has ten to twelve spines and fifteen or sixteen rays with a slight notch in between. The lateral line ends under the end of the spiny dorsal. Their skin is smooth without scales.
The Barnaclebill Blenny is a coastal resident found in the intertidal shallows, bays, and estuaries in rocky areas. They inhabit empty barnacle shells normally with the head protruding, for which they are named, at depths up to 33 feet. They reach a maximum length of 12.0 cm (4.7 inches). The Barnaclebill Blennies are diurnal, highly territorial predators that feed on floating debris and benthic crustaceans including small crabs. Reproduction is oviparous in distinct pairs with the female depositing eggs in protected areas that are sticky and adhere to the walls of the parent’s shelter which are then fertilized by the males who then guards them for two to three weeks until they hatch. In Mexican waters of the Pacific the Barnaclebill Blenny is found south of Magdalena Bay along the west coast of Baja, in the lower two-thirds of the Sea of Cortez and along the coast of the mainland south to Guatemala. They are one of the few species that have migrated through the Panama Canal into the Atlantic. They are a small, shallow-water species and not much is known about their behavioral patterns.
The Barnaclebill Blenny can be confused with the Bay Blenny, Hypsoblennius gentilis (flank with rows of white blotches) and the Mussel Blenny, Hypsoblennius jenkinsi (mottle brown with a row of white spots along the sides below the mid-line).
The Barnaclebill Blenny is too small to be of interest to most and normally a “catch-and-release.”