Hammerhead sharks like to hang out in groups, especially during the summer when huge numbers of them migrate to cooler waters. Hammerhead sharks also take great pride in their appearance, especially their fins. Like their head, they’re a bit unusual—their dorsal fin is very tall and shaped like a sickle.

Unfortunately, humans like their fins, too. Many hammerhead sharks have been killed for their fins to be used in shark fin soup, as well as for their liver oil for vitamins. Sometimes people just slice off the fins and dump the hammerhead shark back into the ocean, where they bleed to death. Plus, they’re at risk for being caught as bycatch when fishermen catch them while they’re looking for food. Because of these threats, many hammerhead sharks are threatened or near threatened and some species, like the great hammerhead and scalloped hammerhead, are endangered.