what is the difference between an octopus and a squid

An octopus has 8 arms, while a squid has 8 arms plus 2 longer tentacles. Octopuses are usually rounder, live near the seafloor, and are more solitary; squids are usually more streamlined, live in open water, and are often more active swimmers.

Main differences

Feature| Octopus| Squid
---|---|---
Arms/tentacles| 8 arms 12| 8 arms + 2 tentacles 12
Body shape| Rounder, softer body 24| Longer, more torpedo-shaped body 24
Habitat| Usually on the seafloor or in dens 13| Usually open ocean 13
Social behavior| Mostly solitary 14| Often swim alone or in schools 14
Movement| Flexible, good at squeezing into crevices 14| Built for faster swimming 4

Easy way to tell them apart

If it has 8 sucker-covered arms and a round body, it’s probably an octopus. If it has a more elongated body, fins, and 10 limbs total , it’s a squid.

Tiny memory trick

Think: octopus = “8 only,” squid = “8 + 2.” That one detail catches the biggest difference fast.

TL;DR: octopuses are 8-armed, rounder, and bottom-dwelling; squids are 10-limbed, more streamlined, and open-ocean swimmers.