The octopus is one of the most well-recognized animals in the sea, but what about their lesser-known cousins? Squid and cuttlefish may not get as many Hollywood roles as their eight-armed relatives, but they’re equally as interesting. Take a minute to explore these tentacled invertebrates—and learn how to tell them apart.
Let’s start with what they have in common. Both squid and cuttlefish are part of class Cephalopoda, which is a type of mollusk that also includes octopus and nautilus. Unlike other mollusks, like clams and snails, most cephalopods have lost their hard outer shells. Cephalopods get their name from the Greek word meaning “head-feet”, because their arms encircle their heads. Both squid and cuttlefish are known as ten-armed cephalopods because they have eight short arms and two long tentacles (as opposed to eight-armed cephalopods like octopuses).