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- Type of predatory marine mollusc with the
- mouth and head surrounded by tentacles. They
- are the most intelligent, the fastest-moving,
- and the largest of all animals without
- backbones, and there are remarkable
- luminescent forms which swim or drift at
- great depths. Cephalopods have the most
- highly developed nervous and sensory systems
- of all invertebrates, the eye in some
- paralleling closely that found in
- vertebrates. Examples include octopus, squid,
- and cuttlefish. Shells are rudimentary or
- absent in most cephalopods. Typically they
- move by swimming with the mantle (fold of
- outer skin) aided by the arms, but can squirt
- water out of the siphon (funnel) to propel
- themselves backwards by jet propulsion. They
- grow very rapidly and may be mature in a
- year. The female common octopus lays 150,000
- eggs after copulation, and stays to brood
- them for as long as six weeks. After they
- hatch the female dies, and, although
- reproductive habits of many cephalopods are
- not known, it is thought that dying after
- spawning may be typical.
-