Overview
The subclass Elasmobranchii have 5-7 separate gill openings on each side of the head; the dorsal fins and spines (if present) are rigid; dermal placoid scales are usually present; the upper jaw is not fused to the cranium; teeth are numerous and their replacement is rapid; and a spiracle opening is present.
Elasmobranchs are a rich and diverse group of sharks, skates and rays. In New Zealand they comprise six orders of sharks and dogfishes, with 18 families and at least 71 species, and one order of skates and rays, with five families and at least 22 species.
The number of endemic elasmobranch species recognised is currently 23, but this is likely to change as more new species are collected and as ongoing taxonomic research better resolves their identity and relationships. Endemism is likely to be high among groups that have relatively poor dispersal ability (e.g. catsharks, benthic skates). Tope, rig (family Triakidae) and skates (Dipturus spp. family Rajidae) are commercial species in coastal waters, and many elasmobranchs are discard bycatch-species in both demersal and pelagic fisheries.