Barnaclebill Blenny, Hyposoblennius brevipinnis
Barnaclebill Blenny, Hypsoblennius brevipinnis. Fish caught from coastal waters of San José del Cabo Rió, Baja California Sur, April 2022. Length: 7.9 cm (3.1 inches). Catch, photograph and identification courtesy of Luke Ovgard, Klamath Falls, Oregon.
Barnaclebill Blenny, Hypsoblennius brevipinnis. Underwater photographs taken in Zihuantanejo Bay, Guerrero, March, November, December 2018 and January 2019. Photographs courtesy of Ron Woheau, Zihuantanejo. Note the most interesting blue margin of the dorsal fin and the very different coloration of the faces!
The Barnaclebill Blenny, Hyposoblennius brevipinnis, is a member of the Combtooth Blenny or Blennidae Family, and is known in Mexico as borracho vacilón. 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 Ocean. The Barnaclebill Blenny is one of the few species who have migrated through the Panama Canal into the Atlantic and can now be found in both the Atlantic and the Pacific Oceans.
The Barnaclebill Blenny has a shortened elongated body with a uniform depth throughout and significant tapering at the rear into the tail. They are dark brown with very subtle colorations including 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 broad dark band running the length of the body slightly above the mid-line. They are off-white to yellow ventrally. Their head has small brown spots and a prominent oblique band behind the eyes. Their eyes have a dark-edged whitish stripe on their upper and lower margins. The head of breeding males is covered with red spots. Their head is short and robust with a very steep forehead profile. The outermost orbital cirri are unbranched but with 1 to 4 shorter cirri at the base. Their mouth is small, opens at the front, and is equipped with 1 row of teeth with blunt flattened tips on each jaw. Their anal fin has 2 spines and 14 rays; their caudal fin is rounded; and their dorsal fin has 10 to 12 spines and 15 or 16 rays with a slight notch in between. Their skin is smooth and without scales. Their lateral line terminates under the end of the spiny dorsal fin.
The Barnaclebill Blenny is a coastal species found in the intertidal shallows, bays, and estuaries in rocky areas at depths up to 10 m (33 feet). They reach a maximum of 12.0 cm (4.7 inches) in length. They inhabit empty barnacle shells normally with their heads protruding, for which they are named. They are diurnal, highly territorial predators that feed on floating debris and benthic crustaceans including small crabs. Reproduction is oviparous in distinct pairs with the females depositing eggs in protected areas. The eggs are sticky and adhere to the walls of the shelter; they are then fertilized by the males who guard them for 2 to 3 weeks until they hatch. The Barnaclebill Blenny is poorly studied with very limited information available about their lifestyle and behavioral patterns including specific details on age, growth, longevity, movement patterns, diet, habitat use, and reproduction.
The Barnaclebill Blenny is a resident of Mexican waters of the the Pacific Ocean but has a limited range being found from Magdalena Bay, Baja California Sur, southward along the southwest coast of Baja, in the lower two-thirds of the Sea of Cortez, and along the coast of the mainland south to Guatemala.
The Barnaclebill Blenny can be confused with the Bay Blenny, Hypsoblennius gentilis (rows of white blotches on flank) and the Mussel Blenny, Hypsoblennius jenkinsi (mottled brown with row of white spots along sides below mid-line).
From a conservation perspective the Barnaclebill Blenny is currently considered to be of Least Concern with stable, widely distributed populations. They are too small in stature to be of interest to most.