Squid and octopuses, both cephalopod molluscs, have a good deal in common: advanced intelligence, dazzling colour-changing skin and defensive jets of ink, for example. But over the 270 million years since their ancestral lines split, each group has evolved its own particular brand of life.
How to tell the difference between a squid and an octopus
The simplest way to tell squid and octopuses apart is to sort through their collection of slippery limbs and count them. As the name suggests, every octopus has eight arms – limbs with suckers dotted all the way along.
A squid, on the other hand, has not just eight arms but also two tentacles, with suckers just at the end, which it uses to hunt fish and shrimp. Other differences include their preferred habitats. Most octopuses live close to the seabed, while squid zip through open seas.
Their mating habits are also dissimilar. Octopuses mate in pairs, and females guard the resulting eggs until they hatch. Squid, though, mate in groups then leave eggs stuck to rocks and corals, investing no more effort in their offspring.
Main image: White-spotted octopus (octopus macropus) in the Mediterranea sea© Getty Images
