They have bulbous heads, large eyes, and eight very useful arms. Octopuses are highly intelligent animals, masters of camouflage that have evolved an array of tricks over tens of millions of years to avoid or thwart would-be attackers.
They can match the colors and even textures of their surroundings, allowing them to hide in plain sight. If a predator gets too close octopuses can escape quickly, shooting themselves forward by expelling water from a muscular tube called a siphon.
Their soft bodies mean octopuses can fit into impossibly small nooks and crannies, as long as the holes are not smaller than the only hard parts of their bodies: their beaks. If all else fails, octopuses can lose an arm to an attacker and regrow one later. Octopuses can open clamshells, maneuver rocks—even dismantle the filtration systems of an aquarium tank. Another shot a jet of water at a light to cause a commotion. There are around species of octopus and they are found in every ocean.
Most live on the seafloor , but some, like the paper nautilus , drift nearer to the surface. Octopuses mostly feed on crabs, shrimp, and mollusks. Solitary animals, they typically live alone, sometimes in dens they build from rocks, sometimes in shells they pull over on top of themselves.
The next largest group is Bivalvia , the clams, oysters, and mussels. These are mollusks with two shells that they can close up tight for protection. Finally there is Cephalopoda , the squids and octopuses.
They only live in salt water, so we won't say much about them here. They have no shells, but are larger, smarter, and faster than their relatives in the other groups. Squids and octopuses are all predators; they eat fish, crustaceans, and other mollusks. Some are very rare and are only found in very deep-water. Mollusks have three body regions. The head contains the "brain" and the sense organs.
The "visceral mass" contains the internal organs. The "foot" is the muscular part of the body. Mollusks usually, but not always, have a shell, which is secreted by a body wall called the mantle. Many mollusks have a tongue of sorts, called a radula. The radula is rough like sandpaper. Mollusks have well developed body organs that are used in the respiratory, circulatory and nervous systems. The stomach-foots include snails, limpets and abalones, which have shells. Slugs and nudibranchs are also stomach-foots, but do not have shells.
End of story. Cell Press. In fact, the octopus is thought to have evolved from a snail-like ancestor whose foot evolved into eight long and slender arms, giving the animals enormous flexibility. Octopuses also developed excellent vision, a large brain and camouflage capabilities , making them adept hunters. Live Science. The original paper in Current Biology , incidentally, had almost nothing to say about evolution: just one quick reference in the last sentence:.
Our results also support the embodied-organization concept of adaptive behaviors in the general sense, not only in octopuses as they show the marvelously reciprocal interaction between the control system , the physical properties of the body, and the morphology , an interaction that leads to an evolutionary successful adaptation of the emerging behavior to the ecological niche. This juxtaposition of design concepts with evolution is awkward.
Looking at each complex, elegant creature in the biosphere with design in mind is the key to understanding, motivation, and application. Image credit: Harrieta File:Knossos frise pieuvre. If so, would you donate so it can continue? Help provide a platform for me and other scientists to keep telling the truth about Darwin and intelligent design in We rely completely on readers like you to make our articles possible.
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