The Octopus – Eight Arms, 3 Hearts and Nine Brains
Of all the animals a diver might encounter, the octopus most easily qualifies as a creature from outer space. But, despite their eight arms, three hearts, nine brains and blue blood, octopuses really do have an earthly lineage. They are a mollusk (think oysters and conchs), but gave up their shells around 400 million years ago. In that time, nature has figured out some strange but effective ways for this animal to eat without being eaten.
Dispensing with its shell gave the octopus flexibility and mobility. To take advantage of their mobility, the octopus features eight flexible, sucker-equipped arms. With these arms octopuses can pull themselves in any direction over the ocean bottom or swim through open water. For real emergencies, they can squirt a blast of water from their siphon for a jet-propelled take-off.
Just about every part of an octopus except its beak and eyes can flow like Silly Putty. Consequently, an octopus can work its way through just about any opening it can get its beak through. That means an octopus has lots of places to hide.
Octopuses have turned hiding into an art form. Their skin contains millions of chromatophores—cells that contain red, orange, yellow, brown or black pigment. Each cell can be individually expanded or contracted, to show or hide color and change the texture of their skin. This allows the octopus to match its surroundings in a fraction of a second as it moves.
The most alien characteristic of octopuses is probably their eight arms. Each arm has double rows of suckers that not only grasp, but also taste. As an octopus hunts the ocean bottom, the arms independently probe cracks and crevices in search of prey. If it appears those arms have minds of their own, they do. While an octopus has about 500 million neurons, only about a third of them form the central brain. The remaining two-thirds are equally divided among the eight arms, putting them where they can most efficiently interact with those myriad muscles, sensors and chromatophores.
Where do Octopus hang out?
So where does a diver go to encounter these amazing animals? My favorite local spot is the Blue Heron Bridge. Octopus studies at the site, led by local researcher Chelsea Bennett, have found common octopus, the Atlantic longarm octopus, Caribbean two-spot, Caribbean reef, pygmy and brownstriped octopuses there.
Since octopuses are so good at hiding, Chelsea offered advice from her many hours of octopus observation. “The common and the logarm octopuses are generally found in high densities at the east and west end of BHB (typically just south of the bridges). I call these species underwater neighbors because they are both found in same areas but can coexist because they are associated with different substrates. The common octopus lives in hard-bottom areas (rock, rubble, shell) and the Atlantic longarm in sandy plains.”
By John Lidington
Pura Vida Divers is featuring Blue Heron Bridge Diver specialty courses throughout the month of March.
You’ll learn to navigate the site, identify wildlife and recognize indicators of dens for animals like octopuses.
Sign up for an upcoming class by calling 561-840-8750