gill cleft การใช้

At an embryonic length of, the gill clefts close dorsally, leaving the gill slits beneath the disc as in all rays.
Members of this subclass are characterised by having five to seven pairs of gill clefts opening individually to the exterior, rigid dorsal fins and small placoid scales on the skin.
Members of the elasmobranchii subclass have no swim bladders, five to seven pairs of gill clefts opening individually to the exterior, rigid dorsal fins, and small placoid scales.
Snout and head are densely covered with speckles that extend posteriorly to nuchal area and onto gill cleft . Scales over flanks fringed by diamond-shaped darker outlines ( scale-pockets ), thicker over posterio-ventral half, giving the flanks a reticulate appearance.