Sailfin Signal Blenny, Emblamaria piratica

Sailfin Signal Blenny, Emblamaria piratica. Underwater photographs taken in Zihuantanejo Bay, Guerrero, in February 2022. Photographs courtesy of Ron Woheau, Zihuantanejo.

The Sailfin Signal Blenny, Emblamaria piratica, is a member of the Tube Blenny or Chaenopsidae Family, and is known in Mexico as known tubícola de Cortés. Globally, there are seventeen species in the genus Emblamaria, of which four are found in Mexican waters, one in the Atlantic and three in the Pacific Ocean.

The Sailfin Signal Blenny has an elongated body. They are dimorphic with the males having a dark brown head, a lighter brown head and the sides with faint brown bars and white flecks. Their dorsal fin is black in the front transitioning to broad yellow or red areas between diagonal black bands. The females are lighter in color and sometime translucent with a mid-lateral row of brown spots and numerous white flecks on the sides. They have a short blunt head that does not have spines. They have one unbranced cirrus over that eye that is longer than the eye. They have one row of teeth on the roof of the mouth. The anal fin has 2 spines and 21 to 23 rays, their first dorsal fin has 20 to 21 spines; the second dorsal fin has 13 or 14 rays their pectoral fins have 21 to 23 rays; and, the pelvic fins are longer than the pectoral fins. The males have a large, sail like front dorsal; the first three dorsal spines of the females are elevated.

The Sailfin Signal Blenny are found demersal in empty mollusk tubes on sand bottom in shallow waters at depths up to 30 m (100 feet). They reach a maximum of 4.0 cm (1.6 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 are known to have very poor eyesight and to exhibit fearless and extremely aggressive behavior in captivity and will attack anything large or small that approaches their home. They feed primarily on zooplankton. The Sailfin Signal 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 Sailfin Signal Blenny is a resident of Mexican waters of the Pacific Ocean but has a limited range being found from Mazatlán, Sinaloa south along the coast of the mainland south to Guatemala.

The Sailfin Signal Blenny is similar to and can be confused with the Elusive Signal Blenny, Emblemaria walkeri and the Gulf Signal Blenny, Emblemaria hypacanthus (both are out of range being found along the east coast of the Baja within the Sea of Cortez).

From a conservation perspective the Sailfin Signal Blenny is currently considered to be of Least Concern with stable, widely distributed populations. They are small in stature and of limited interest to most.