Darkfield Digital Image Gallery Dogfish Shark Placoid Scales Dogfish sharks are small sharks belonging to one of three families: the dogfish shark family, Squalidae; the requiem shark family, Carcharhinidae; and the cat shark family, Scyliorhinidae.he green dogfish, along with several other members of the dogfish shark family, is luminescent. Scales are small plates that form part of the skin of certain animals. They provide protection from the environment and from predators. Sharks have placoid scales, bony, spiny projections with an enamel-like covering.