Octopus, also known as octopus (English name octopus), the same marine mollusks.
Octopoda (Octopus) cephalopod mollusks. However, strictly speaking, it refers only to the octopus genus (Octopus) animals, widely distributed in shallow water.
The size of octopuses varies greatly. The smallest octopus is the arborescent octopus (O. arborescens), which is about 5 centimeters (2 inches) long, while the largest species can be up to 5.4 meters (18 feet) long, with a carapace spread of up to 9 meters (30 feet). The body of a typical octopus is sac-like; the head is not clearly separated from the carapace, and is surmounted by large compound eyes and eight retractable wrists. Each wrist has two rows of fleshy suckers that provide a strong grip. The base of the carapace is connected to webbed tissue called the skirt, which has a mouth at its center. The mouth has a pair of sharp, horny palates and a file-like toothed tongue, which is used to bore through shells and scrape their flesh.
The octopus draws water into its coat membrane, breathes it in, and then expels it through a short funnel-shaped body tube. Most octopuses crawl along the seabed on suction cups, but when startled, they eject a stream of water from their body tubes and move quickly in the opposite direction. When in danger, they emit an ink-like substance that serves as a smoke screen. Some species produce a substance that can paralyze an attacker's sense organs.
The most familiar octopus is the common octopus (O. vulgaris), medium-sized, widely distributed in tropical and temperate seas around the world, inhabiting the rocky seabed in caves or crevices, preferring to stay hidden. It mainly feeds on crabs and other crustaceans. This species is considered to be the highest invertebrate intelligence, and has a highly developed pigment-containing cells, so it can change its body color very quickly, and the rapidity of the change is also surprising.
Octopus dioecious. The male has a specialization of the wrist, known as the stem wrist or handing wrist, used to put the sperm packet directly into the female body of the coat cavity. The common octopus mates in winter. Eggs are about 0.3 centimeters (1/8 inch) long, totaling more than 100,000, and are laid under rocks or in caves. Juveniles hatch after 4, 6, or 58 weeks, and during incubation the female guards the eggs, cleaning them with a suction cup and stirring them with water. The juvenile octopus is small and similar in shape to the adult, and after hatching, it drifts along with the plankton for a few weeks before sinking to the bottom and hiding.
The octopus feeds mainly on shrimp and crabs, but some species eat plankton. Many marine fish feed on octopus. In the Mediterranean region, Eastern countries and some other parts of the world, people have long regarded octopus as a delicacy.
Octopoda (Octopoda) cephalopod mollusks of the common name. But strictly speaking only refers to the octopus genus (Octopus) animals, widely distributed in shallow water.