What is a Cephalopod?

Seeing as these guys exclusively live in the ocean, let's dive right into the world of cephalopods! Cephalopods are in the family of mollusks, the same way that lizards would be in the family of reptiles. So right away cephalopods have some unique traits:

  • They are marine animals, only found in the oceans
  • They are invertebrates, and some of the most neurologically advanced invertebrates on our planet
  • There are roughly 800 living species of cephalopods
  • Is the class that has the largest known invertebrate species, the giant squid and colossal squid
  • Cephalopods have a mantle, a radula, and and the structure of a nervous system as their most universal features


Aside from the Nautilus and some deep-sea octopuses, all cephalopods can release ink, generally as a defense mechanism. This has led some fisherman to refer to this group of animals as "inkfish". Vision is the sense cephalopods use most for detecting predators and prey, as well as communicating with each other. Training experiments have shown that even the common octopus can notice differences such as size, shape, brightness, and more, from objects it has seen. Some species of Cephalopods include...


  • Squids
  • Octopuses
  • Cuttlefish
  • Nautilus


No cephalopod can tolerate freshwater so they are only found in the ocean. However one species, the Atlantic brief squid, can tolerate brackish water. Cephalopods are regarded as the most intelligent invertebrates, with large brains, well developed senses, and a very complex nervous system. Cephalopods in captivity have been observed climbing out of the aquarium they live in, going to another to feed on crabs, and then returning back. Many of them are social creatures, and when they are separated from their own species, they can sometimes be found schooling with fish. Cephalopods can also change their coloration and patterns extremely fast, helping with camouflage as well as warning coloration to deter predators. Physically they are known for their two-part beaks they use for eating, and the arms and tentacles extending from their heads.



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