Octopuses tend to be solitary, but squid are often found in shoals making them a commercially viable species for fishermen to catch. Cuttlefish have an internal calcareous shell, squids have a thin cartilaginous pen, and in octopods the shell Coleoidea ( squid, cuttlefish and octopus)Įxternal shell. There are two Sub-classes, the Nautiloidea with six species, and Coleoidea which includes the squids, octopuses and cuttlefishes. The ink cloud can act as a decoy to a predator allowing the cephalopod to escape. They also have an ink gland which releases a cloud of ink through the anus when the animal is alarmed. They have a radula and a pair of beak-like jaws. This funnel is used in movement when water isįorcibly expelled through it, a form of jet propulsion. With suckers around the mouth, with one or two modified for sperm transfer (see mating below) and a muscularįunnel in the mantle cavity. The foot has developed into a number of prehensile arms They have a wide range of behaviours, a relatively large andĬomplicated brain, and a great capacity for learning. The cephalopod fossil record goes back to the Cambrian, and were similar to the nautilus extant today. There are about 660 species and a large size range, the Giant squid ( Architeuthis sp.), can be over 20 m long. The most sophisticated molluscs, and possibly the most intelligent Cephalopoda overview - cephalopod body - Coleoidea (squid cuttlefish and octopus) - eyes - chromatophores - mating Class
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