The genera and species of "Sawsharks"

Saw sharks are a very unusual group of sharks with a very long flat snout and lateral sawteeth. The snout resembles a saw with ventral barbels. Saw sharks are often confused with saw fishes, which are rays. Most obvious differences between these two groups are that rays lack barbels, and have their gill slits on the ventral side. Furthermore, saw sharks are of smaller size, compared to saw fishes. The biology of saw sharks is poorly known. Except for the Bahamas sawshark, Pristiophorus schroederi, all of them live on the southern hemisphere. All prefer deeper water and show an aplacental viviparous style of reproduction (ovoviviparity). Of the only 5 species known, one of them, Pliotrema warreni, possesses 6 pairs of gill slits.