Lacks dorsal fin spines. It has a slender body with a very short, blunt snout, large eyes, and thick lips. Its teeth are highly differentiated between the upper and lower jaws, with the upper teeth small and narrow and the lower teeth large, triangular, and serrated. Its typical length is 1.0–1.4 m.

It is found sporadically around the world, usually close to the sea floor at depths of 200–600 m.

Armed with large teeth and a strong bite, the seal shark is a powerful, solitary predator that takes many different types of prey, ranging from bony fishes, sharks and rays, to cephalopods, crustaceans, polychaete worms, siphonophores, and possibly carrion. It also takes bites out of animals larger than itself, similar to its smaller relative, the cookiecutter shark (Isistius brasiliensis).

This shark is aplacental viviparous and has 10-20 young born at 30-42 cm.
. Closely related to the Cookie Cutter Shark which is famous for it's eating habits.

Deep New Zealand: Batson P