Squid Squid are cephalopods in the superorder Decapodiformes with elongated bodies, large eyes, eight arms, and two tentacles. Like all other cephalopods, squid has a distinct head, bilateral symmetry, and a mantle. Squid are rapid swimmers, moving by jet propulsion, and largely locate their prey by sight.
Squid are cephalopods in the superorder Decapodiformes with elongated bodies, large eyes, eight arms, and two tentacles. Like all other cephalopods, squid has a distinct head, bilateral symmetry, and a mantle. Squid are distinguished by their enlarged ends of the body used for jet propulsion by water expulsion. The ends of the arms and tentacles are lined with suckers, but these have lost their ancestral function of catching prey in some species. An adult squid has ten arms arranged in two rows of five on either side of its body, and two long tentacles that can be up to twice as long as an arm span. Many squid species, such as the Humboldt squid, can discard some of their arms. Like all cephalopods, squid use organs known as statocysts (balance organs) to keep upright and in their proper habitat.
Squid is equipped with two highly developed eyes sensitive to light and color. The eyes include hard lenses, corneas, and retinas. Squid can thus form a clear image of objects with great detail. Beyond these simple eyes, squid has complex photoreceptive cells that can distinguish between different wavelengths of light as well as polarized light. These photoreceptors give the squid an acute sense of vision at their disposal. However, they are not very useful when out of the water, because salt water is so much denser than air. Squid are also able to perceive the polarization of light with these photoreceptors, making it possible to orient themselves in the ocean or navigate through cloudy waters.
Squid have eight arms arranged in pairs and two longer tentacles that cross over their mouth-ventral sides. The arms and tentacles of the squid are attached to muscular bands along their body which keeps them rigid and is similar to a skeleton. Squid move by either swimming with their fins, crawling with their arms and tentacles, or "walking" along the sea bottom using their arms and tentacles, this last way being most common among octopus species.