The broadnose sevengill is a type of cowshark. Cowsharks and their close relatives, the frilled sharks, are grouped into the same order: Hexanchiformes.
Often called “fossil sharks,” these sharks don’t have many of the modern features of other sharks, including better senses, a more efficient digestive system, and jaws that are not connected to their heads (which would let them thrust their heads forward to catch prey). Their skeletons so closely resemble fossils of the earliest sharks that many scientists believe they are closely related to sharks that lived more than 300 million years ago.
While frilled sharks and cowsharks look pretty different from one another, all sharks in this order have a few things in common. They all have extra gills, big mouths, eyes on the sides of their heads, spineless back fins, and an arrangement of vertebrae that’s different from most other sharks.
The origin of the name “cowshark” is not known, but it may be due to the shark’s heavy body and slow movement. There are four types of cowshark (the bigeye sixgill, bluntnose sixgill, broadnose sevengill and sharpnose sevengill) ranging in size from 5 to 14 feet long on average.