Membras martinica has an elongated body with a rather pointed snout and oblique mouth. The color is pale yellow to off-white with silvery stripe along the flanks and a white swimbladder which can be seen through its flesh. There are two dorsal fins, there are only spines in the first dorsal fin. The pectoral fins are situated high on its flanks. The back has parallel colored rows. This species has scales which are rough to the touch. The caudal fin has a dusky margin. The maximum recorded total length of.
Membras martinica is a pelagic species which occurs in a variety of different habitat types. The normal habitat is exposed shoreline and beaches where there is a firm substrate is also occurs on coastal rivers. On the coastlines around the Gulf of Mexico the females are ripe in the warmer months from early Spring in to the early fall with a hiatus reported between May and July. This results in two size classes of juveniles each year. Spawning occurs just beyond the surf zone and the eggs are demersal and stick to each other, forming large clusters which are transported into the intertidal zone by the waves.