What a bunch of suckers

So recently I made a blog about tool usage in non-human animals to show the wide range of intelligence in different species. However, there is one species, or more accurately group of species, that I didn't mention in that post which cannot be overlooked when discussing the most intelligent animals on the planet.

Left-Right: Giant Pacific Octopus, Enteroctopus dofleini; Flamboyant Cuttlefish, Metasepia pfefferi; and the Hawaiian Bobtail Squid, Euprymna scolopes.

The octopus, squid, and cuttlefish pictured above are all Cephalopods, and are in fact grouped together in the subclass Coleoidea. Cephalopods are considered the most intelligent invertebrate group for several reasons. Firstly the brain-body mass ratio, a common rough estimate of intelligence in species, is higher among octopuses and cuttlefish than any other invertebrate. Bigger brains relative to body size is considered a good estimate of animal intelligence, although the estimation is imprecise and not fool-proof. Another example of Cephalopod intelligence is their tool use, which I touched on in other species previously. The veined octopus, Amphioctopus marginatus, has been observed collecting discarded coconut shells on the sea floor, cleaning them out, and then carrying them awkwardly away.

Veined octopus, Amphioctopus marginatus, carrying coconut shells to use as shelter.

This behaviour might seem odd at first, but all becomes clear when the octopus settles down and constructs a "tent" out of the shells for protection. This collection and preparation of objects, as well as the continued and clearly conscious use of them for a specific purpose fulfills all the requirements of tool usage which, as discussed in previous posts, is a major indicator of intelligence. While some of you may be surprised at the intellect of these humble molluscs, their dexterity, and curiosity have been documented several times before. Octopuses held in captivity have been known to break bits of their tanks causing aquariums to flood, spray feeders with water, juggle tank mates, and smash aquarium tanks with rocks. There are also multiple stories (and you've probably all heard one of these) about octopuses escaping their tanks at night and visiting some of their fellow aquarium species. Specifically stories mention a nearby lobster tank which is invaded by the eight-legged adventurer who then proceeds to kidnap several lobsters. Aquarium staff are reported to return the next day and find they are missing lobsters. The stories go on to describe investigations into lobster thieves, added security measures, and the eventual discovery of the culprit in the act. Following examinations of the octopus's tank the remains of discarded lobsters are found secreted away beneath rocks.

Octopus displaying its dexterity, strength, and ingenuity by opening a jar while inside it.

Cuttlefish and other Cephalopods are renowned for their amazing, near instantaneous, color changing capabilities. While this ability is certainly beneficial for camouflage, it has also been adapted in some species of Cephalopod for use in communication. Species such as the Caribbean reef squid, Sepioteuthis sepioidea, which utilizes chromatophores, pigment rich cells, to flash color signals to other squid, usually as part of a courtship ritual. The squid can even send different signals to fellow squid on opposite sides simultaneously!

Sir David Attenborough discussing various amazing abilities of Cephalopods.

While these creatures are unquestionably intelligent scientists are just beginning to discover how smart they really are. Research has shown that octopuses have on average around 130 million neurons in their brain which doesn't seem like a lot when compared with the 100 billion in the human brain. However, two-thirds of the neurons in an octopus's body are spread throughout it's arms rather than concentrated in the cerebral cortex like vertebrates. In terms of total number octopuses actually have more neurons than several species of rats and mice. The location of the neurons in their arms is theorized to grant them the ability to operate all of their limbs independently, as they each have "a mind of their own" so to speak. Studies where researchers have severed a limb of an octopus (they can grow back calm down) have shown that the limbs not only move on their own, but will seize any item it "perceives" as food. This is similar to our reflex to drop anything which is too hot to avoid burning ourselves.

All in all Cephalopods are some of the most intelligent species on the planet ranking up there with dogs, mice, and even the great apes in some areas. Not bad for animals that are cousins with the clam. So I will leave you with two great videos of some True Facts About The Octopus and Cuttlefish courtesy of zefrank1 on Youtube.

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