Cephalopods (meaning “head foot”) are some of the most astonishing creatures in the animal kingdom. The extant subclass called Coleoids (squids, octopuses, and cuttlefish) are essentially a bilateral head and body unit surrounded by multiple muscular, grasping arms (used primarily in predation). The other remaining subclass is the shelled Nautiloids, which are now represented by only two remaining genera, while extinct species were once far greater in numbers. Cephalopods are known for being the most intelligent of the invertebrates, exhibiting extraordinary skills in navigation, predation, learning, mimicry, and communication. A variety of cephalopods employ colored pigments in their skin called chromatophores, which can allow a cephalopod to change color and display bioluminescence for signaling and communication. If camouflage doesn’t work against a predator, then a cephalopod (with the exception of nautiluses) can secrete a cloud of ink to mask its escape. Cephalopods have an extremely rich prehistory that goes all the way back to the Cambrian period, approximately 540 million years ago. The earliest floor-crawling forms would eventually evolve into habitual swimmers, complete with a protective, gas-filled shell that could help increase or decrease buoyancy. From the Cambrian forward, great numbers of nautiloids and ammonoids (including the famous Ammonites) would fill the oceans and diversify into thousands of species. Future extinction events would cut down the number of shelled cephalopods considerably, leaving only a handful of nautilus species left today, in addition to the hundreds of shell-less and highly intelligent squids, octopuses, and cuttlefish.
SQUIDS & OCTOPUSES