Octopuses are one of the few invertebrate animals whose intelligence rivals our own, yet they evolved their brains in an environment which is completely alien to us. Lisa O’Dowd explores.
In the 1980s, several rare fish disappeared from their tank at an aquarium in Boston. Workers were scratching their heads wondering what had happened. A researcher arrived early one morning and caught an octopus mid-dinner. The octopus had been escaping its tank and entering the fish tank for an extra feed before returning to his own tank in time for the morning. This octopus was the culprit for the missing fish.
In late February 2009, an aquarium in Santa Monica, California was flooded with saltwater. CCTV footage filmed the unravelling scene. It showed an octopus disassembling a water recycling valve and directing a tube to spew out of the tank. When workers arrived, the octopus in question was in its tank looking on at the chaos around him, innocent as could be.
“These animals are unique amidst
invertebrates as they have an extremely large nervous system that contains a similar amount of neurons as the brain of a dog or a human infant.”
In the fifth episode of Blue Planet, ‘Green Seas,’ viewers witnessed an octopus performing an act that would be sure to be guaranteed an Oscar. A pyjama shark is seen hunting down a common octopus. The two got into a tussle, and when death seemed almost inevitable, the octopus plugged her tentacles into the shark’s gills, forcing the shark to release its hold to breathe. The octopus then created a cunning camouflage by attaching empty shells to the suckers on her arms, forming a dome and protecting herself inside. The structure made of shells fooled the shark for just long enough for the octopus to escape. It came as no surprise when the cameraman exclaimed that the octopus was a “Rockstar!”
Anecdotes such as these have circled the oceans for centuries, but photographic evidence of the octopus’ incredible behaviours is now accessible to the world of science.
Octopuses belong to a class of animal called Cephalopods, which also includes squid and cuttlefish. These animals are unique amidst invertebrates as they have an extremely large nervous system that contains a similar amount of neurons as the brain of a dog or a human infant. Peter Godfrey-Smith, in his book Other Minds: Octopus and the Evolution of Intelligence describes cephalopods as “an island of mental complexity in the sea of invertebrates.” Cephalopods developed independently of vertebrates which makes their development of large brains and complex behaviours extraordinary, as vertebrates have a veritable monopoly on intelligence.
Invertebrate as they are, octopuses are extremely flexible morphologically. They are a delicate mixture of utter simplicity and sophisticated intricacy. Despite our limited knowledge and understanding of these creatures it is agreed that they are a tremendous evolutionary success. The oldest known octopus fossil is Pohlsepia and lived around 296 million years ago. However, as octopuses are mostly made of soft tissue, with their only hard body part being their beak, fossils are so rare that they may have existed further back than this.
“They change colour and shape to
themselves against the surrounding environment or to morph into the shapes of other species such as sea snakes, flatfish, or lionfish.”
Octopuses have a remarkable ability to solve the problems posed by their ever-changing underwater environment. They change colour and shape to camouflage themselves against the surrounding environment or to morph into the shapes of other species such as sea snakes, flatfish, or lionfish. It is not yet understood how these defence mechanisms arose in their evolution.
In the words of David Attenborough, “Octopuses are extraordinary animals.” Unlike vertebrates, their neurons are found throughout their body, especially in their arms. The density of neurons found here is greater than that found in their brain. There is an evolutionary niche for intelligence in the oceans, and octopuses fill a lot of it. It is thought that the origins of the intelligence exhibited by the octopus evolved in the tropical coral reef, an ecosystem of outstanding beauty, diversity, and complexity. To survive here you must either be armoured by thick skin or a quick wit. As large jelly-like, soft-bodied creatures they are immediately flagged as an easy target. Predators exert strong selection pressure on these creatures. The result is the survival of the intelligent, the greatest hider, the best at leading a solitary life, and the most efficient at adopting tools.
“It is thought that the origins of the intelligence exhibited by the octopus evolved in the tropical coral reef, an ecosystem of outstanding beauty, diversity, and complexity.”
In the face of their apparent intelligence, beauty, and uniqueness we must be careful not to anthropomorphize. Evolutionary chance separates us from them. They were around to see the creation of glaciers, to view the first flight of the birds, to observe the dawn of the dinosaurs, and ultimately to witness the evolution of man. Human intelligence, like most vertebrate intelligence, evolved due to our nature as long-lived social animals. Octopuses developed differenlty over a longer period, and so we must open-mindedly seek to understand how their unique intelligence arose.