Club-head Barnacle Blenny, Acanthemblemaria balanorum
Club-head Barnacle Blenny, Acanthemblemaria balanorum. Underwater photographs taken within Bahía de Banderas, Puerto Vallarta, Jalisco, July 2026. Photographs courtesy of Greg Timms, youtube.com/@CoralmasterdivesPuertoVallarta/videos. Identification courtesy of Dr. Benjamin Victor, Coralreeffish.com.
The Club-head Barnacle Blenny, Acanthemblemaria balanorum, is a member of the Tube Blenny or Chaenopsidae Family, that is also known as the Club-head Blenny and in Mexico as blenia and trambollín cirripedio espinudo. Globally, there are twenty species in the genus Acanthemblemaria, of which six are found in Mexican waters, two in the Atlantic and four in the Pacific Ocean.
The Club-head Barnacle Blenny has an elongated body with a short, blunt head and is named for large bony club-like spines with expanded tips found on the frontal bones on the middle of the head that are found in two triangular patches by a narrow spinless grove. They are normally a tan color with purplish to red heads with a cream bar across the side of the lower jaw under the eye with cream marks behind and below the eyes. Their mid-side has 6 to 8 large dark brown to blackish spots with adjacent pale dashes along the middle of the sides. The head of the breeding males is dark red in front and black at the rear with the black extending into the front of the body. They have spines on the snout and under the eye and cirri on the nostrils and over the eyes. The roof of their mouth is equipped with two rows of well-developed teeth on the sides. Their anal fin has 2 spines and 24 or 25 rays; their dorsal fin has 24 spines and 13 rays; and, their pectoral fins have 13 rays.
The Club-head Barnacle Blenny exclusively inhabits abandoned barnacle shells on rocky reefs in shallow waters at depths up to 5 m (16 feet). They reach a maximum of 5.2 cm (2.0 inches) in length. They enter tail first in the various types of shelter in which they reside and are found with only their head exposed. They feed primarily on zooplankton. Reproduction is oviparous with the females laying eggs inside the barnacle shells which are then guarded by the males until they hatch. The Club-head Barnacle Blenny is poorly studied with very limited information available about their lifestyle and behavioral patterns including specific details on age, diet, growth, habitat, longevity, movement patterns, and reproduction.
The Club-head Barnacle Blenny is a resident of Mexican waters of the Pacific Ocean but has a limited range being found around the tip of the Baja Peninsula in Baja California Sur and along the coastline of the mainland south to Guerrero.
The Club-head Barnacle Blenny is most likely confused with the Cortez Barnacle Blenny, Acanthemblemaria hastingi (mid-lateral row of large brown spots or blotches and seven to nine dark brown saddles along the base of their dorsal fin) and the Mexican Barnacle Blenny, Acanthemblemaria macrospilus (front portion of dorsal fin is red with a black spot).
From a conservation perspective the Clubhead Barnacle Blenny is currently considered to be of Least Concern with stable widely distributed populations. They are small in stature, seldom seen by humans, and of limited interest to most.