Octopus, cuttlefish and squid are in a class of their own in multiple ways. Classified as cephalopods they lack a backbone in their soft bodies but show remarkable intelligence for invertebrates. These savvy softies arouse a great deal of interest in divers and science alike.
Probably the most fascinating aspect of cephalopods is their ability to change colour as well as the texture of their skin in a blink of an eye. This way they can blend in with their surroundings perfectly or show bright warning or hypnotizing patterns at will.
Just below the surface of their skin sit thousands and thousands of chromatophores (colour-changing cells). Each chromatophore contains a sack of a particular pigment (black, brown, orange, red or yellow). By stretching the sack, the colour appears brighter.
A complex system of nerves and muscles controls this magical transformation including the texture of the skin from smooth via small bumps to high spikes. Additionally, some cephalopods have iridophores, plates reflecting greens, blues, silvers and golds, while leucophores mirror the colour of the surrounding to perfect their camouflage.
They use their skill to hide from predators as well as to sneak up on their prey. But colour patterns are also a way to communicate to another or others in the form a flashing bright warning colouration, like the poisonous Flamboyant cuttlefish: King of critters. As a last resort, they can release a cloud of ink and disappear through any hole their bony beak fits through. That’s the only hard part in the body of these savvy softies.
Cephalopods have the largest brain-to-body mass ratio as well as the most complex nervous system among all invertebrates.
“Intelligence is generally defined as the process of acquiring, storing, retrieving, combining, comparing, and recontextualizing information and conceptual skills. [...] The scope of cephalopod intelligence and learning capability is controversial within the biological community, complicated by the inherent complexity of quantifying non-vertebrate intelligence. In spite of this, the existence of impressive spatial learning capacity, navigational abilities, and predatory techniques in cephalopods is widely acknowledged.”
Wikipedia: Cephalopod intelligence
Basically science is still struggling to understand and test certain aspects of the intelligence of cephalopods. Maybe soon there are new ways to measure and validate other forms of their intelligence too.
Almost all cephalopods are active hunters, pushing them to develop certain strategies and behaviour to find and catch their prey. Some crabs, the base of the most octopus food source, have powerful pincers to defend themselves and a long pursuit costs energy. Hence, octopuses are looking how to use the work of others to their advantage, such as stealing bait from lobster traps or climb on board of fishing boats to feast on the dead or dying crabs in containers.
As described above, cephalopods can use skin colouration and texture to communicate. Posture and locomotion add to their display. We were lucky enough to observe flamboyant cuttlefish flashing colours in courtship in Komodo ourselves. Eventually, the bigger female stopped and raised her arms to allow the small male to deliver its sperm. They went on for various rounds.
Especially, squid use colour and (flashing) patterns to communicate, not only in courtship. Caribbean reef squid can send different colour patterns to squids on either side of their bodies at the same time. Humboldt squid use communication even in cooperative hunting techniques.
Learning, use of tools and problem solving
Octopuses can be trained to distinguish between different shapes and patterns. In laboratories, they benefit from an enriched environment, using bottles or toys to play with.
Furthermore, Octopuses have repeatedly shown the ability to use tools. As seen by many divers, they collect, carry and use coconut husks and shells for protecting their soft bodies.
“Cephalopods can solve complex puzzles requiring pushing or pulling actions, and can also unscrew the lids of containers and open the latches on acrylic boxes in order to obtain the food inside. They can also remember solutions to puzzles and learn to solve the same puzzle presented in different configurations.”
Wikipedia: Cephalopod intelligence
Savvy softies: Octopus, cuttlefish and squid
Cephalopods are molluscs with their arms attached to their head. The word is based on old Greek (kephalópodes; "head-feet"). Octopus, cuttlefish and squid all belong to the subclass Coleoidae. We shall take a closer look at the different members of this subclass and add more information and materials.