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.