Squid: That is squid.
Octopus: It belongs to the order Octopus in the phylum Mollusca, and is the general name of octopus. Because it has eight wrists on its head, there are membranes of different lengths connected between them, and there are two rows of sessile suction cups on the wrists, so it is called "eight wrists". It is a marine animal, not a fish. Octopus is short oval and has no fins. The boundary between the head and the body is not obvious. There are big compound eyes and eight retractable wrists on the head. Each wrist has two rows of fleshy suckers. I usually crawl with my wrist, sometimes I swim by stretching my wrist membrane, so that I can hold other things strongly and use the funnel at the bottom of my head to spray water and retreat quickly. The base of the wrist is connected with a reticular tissue called the skirt, and there is a mouth in the center. There are a pair of sharp horny palates and file-like toothed tongues in the mouth, which are used to drill through shells and scrape off their meat. This species is considered to be the smartest invertebrate, with highly developed cells and pigments, which can change body color very quickly.
Squid: also known as squid, sentence male, soft fish. It is an eye-opening suborder of Cephalopoda, a mollusk. The body is slender, long and conical, with more than a dozen wrists, two of which are longer. There is a sucker at the front end of the wrist, and there is a horny toothed ring in the sucker. When preying on food, wrap it around your wrist and swallow it. I like to get together in groups, especially when mating and laying eggs in spring and summer.