What is the difference between squid and octopus? A quick guide to telling the two apart

Octopus is the general name for animals of the genus Octopus in the family Octopodidae; it is a marine mollusk and does not belong to the fish. Squid generally refers to the loligo, a shallow-sea species that lives mainly within the continental shelf; by day it is mostly active in the middle and lower layers, and at night it often rises to the middle and upper layers, with a vertical migration range from the surface down to more than a hundred meters. Let us take a look below at what the differences between squid and octopus are!

The difference in family and genus between squid and octopus

1. Squid: Squid is a mollusk of the animal kingdom, phylum Mollusca, class Cephalopoda, subclass Coleoidea, order Teuthida, family Loliginidae, genus Loligo.

2. Octopus: Octopus is a mollusk of the animal kingdom, phylum Mollusca, class Cephalopoda, subclass Octopodiformes, order Octopoda, suborder Incirrata, family Octopodidae, genus Octopus.

The difference in arms and tentacles between squid and octopus

1. Squid: The squid has a slender body in a long conical shape, with more than ten tentacles, two of which are longer. The front ends of the tentacles have suckers, and inside the suckers are horny toothed rings; when hunting food it uses its tentacles to entangle and swallow it. It likes to gather in groups, especially during the spring and summer mating and spawning season.

2. Octopus: The octopus has a short oval, sac-like body with no fins, and the boundary between head and body is not obvious. On the head are large compound eyes and 8 retractable arms, each arm having two rows of fleshy suckers. It usually crawls with its arms, sometimes swims by stretching and contracting the web between the arms, can grip other objects powerfully, and uses the funnel under its head to squirt water for rapid backward swimming.

The difference in diet between squid and octopus

1. Squid: The squid is a fierce carnivorous animal; its food is mostly small middle and upper layer species such as anchovies, sardines, trevally and krill, and it also preys heavily on its own kind. It is itself an important food source for tuna, mackerel, hairtail and seabirds.

2. Octopus: The octopus feeds on lamellibranchs and crustaceans (shrimp, crabs, etc.), and some species eat plankton. The octopus draws water into its mantle, and after breathing expels the water from its body through a short funnel-shaped siphon. It mostly crawls along the seabed with its suckers, but when startled it squirts a stream of water from its siphon; the jet of water is powerful, moving it quickly in the opposite direction. When in danger it ejects an ink-like substance as a smoke screen, and some species produce substances that can paralyze an attacker's sensory organs.

The difference in distribution between squid and octopus

1. Squid: Squid is distributed in the tropical and temperate seas between 40° north and south latitude. The world's main loligo fishing grounds are in the northern South China Sea, the Gulf of Siam, Kyushu in Japan, the central Philippine Islands, western Western Europe, and the eastern and western seas of the United States. The fishing grounds are mostly located around islands and reefs, where the water is clear and the current slow, the salinity relatively high, the bottom hard and coarse, and the seabed hollowed; they lie where coastal water systems and warm current systems meet.

2. Octopus: Octopus is widely distributed in tropical and temperate seas around the world, and is found along the coasts of both northern and southern China. It lives underwater, and the water temperature it can adapt to must not be lower than 7°C; a seawater specific gravity of 1.021 is most suitable, and it will die in a low-salinity environment. The bottom of the sea area is best a gravel zone.