There are more than 400 living species of sharks, taxonomically grouped into 14–30 families. Several larger species can be dangerous to humans. Numerous sharks are fished commercially. However, overfishing has substantially reduced the populations of some shark species. The whale shark and the basking shark, both of which may weigh several tons, are harmless giants that subsist on plankton strained from the sea through modified gill rakers.

Zebras are strikingly black-and-white striped mammals of the horse family. There are the plains zebra, which is found in rich grassland over much of eastern and southern Africa; the Grevy’s zebra which lives in arid, sparsely wooded areas in Kenya and a few small areas in Ethiopia; and the Mountain zebra which inhabits dry upland plains in Namibia and a few scattered areas in western South Africa.