Octopus or Devilfish; Animals that Adapt their Color to their Environment; Using Its Colour for Camouflage
The octopus, also known as the Devilfish, is an amazing creature! It is able to adapt to its environment rendering itself invisible, or nearly invisible, to escape a predator or to capture its prey!
When I had my marine aquariums, I was often tempted to consider the introduction of an octopus into the underwater world I was creating. Despite my fascination with these wondrous creatures, I was always able to talk myself out of it. One good reason NOT to keep an octopus was that I valued some of the other creatures I had previously decided to keep. They would have made a very tasty, but expensive, meal for the eight armed mollusk. The advice typically given in keeping an octopus in an aquarium is to only keep octopuses in it, and then to only keep one of them. Not very exciting.
Answers.com defines an octopus as: “Any of numerous carnivorous marine mollusks of the genus Octopus or related genera, found worldwide. The octopus has a rounded soft body, eight arms with each bearing two rows of suckers, a large distinct head, and a strong beaklike mouth. Also called devilfish.”
The octopus is a mollusk that has no external or internal skeleton. Because of this, they are able to squeeze through very small openings. So if keeping them in an aquarium, the aquarium must have a very tight fitting lid, or this extremely intelligent escape artist will be out of the aquarium whenever it chooses. And because of their strength, they sometimes use their legs to lift or push the cover right off the tank.
An octopus is able to live for short periods of time out of the water. Some aquarists have reported that their “octopus leaves its own tank, goes across the room, or to a tank beside it, entering that different tank, eats some of the fish or crustaceans, then travels back to its own tank.” That is amazing!
But there are also reports of the octopus drying up on the floor because they didn’t make it back in time! More of the scenario that I would expect!
But enough about keeping them in aquariums, let’s talk about them in their natural environment – the ocean.
In addition to being a mollusk, the octopus is a cephalopod, meaning “head to foot” because the octopus’ feet are attached to its head, like the squid and cuttlefish. Octopuses are very short lived, living only 1-2 years, but most only live to about 6 months. There are approximately 300 species around the world.
The octopus ranges from 1 - 13 feet (0.3 - 4meters) in length. The Giant Pacific Octopus who lives in the coastal waters of British Columbia is the largest octopus in the world. The largest one ever captured weighed about 600 pounds, and its tentacles spanned 33 feet! However, most octopuses are much smaller, with the females rarely exceeding 55 pounds and the male usually averages less than 90 pounds.
The octopus has eight arms with suckers on the full length of them. They use these suckers to attach themselves to objects and to climb. The octopus uses its arms and suckers to catch and choke its prey. The suckers also serve as taste buds. The Giant Pacific Octopus has two rows of suckers on each arm for a total of 1,600 suckers!
Octopuses have a large head and well-developed eyes. However, they are deaf.
The body of the octopus looks like a bag. It moves as the octopus breathes filling with water as the octopus breathes in, and deflating as the octopus breathes out. When the octopus breathes the water out, the water is forced through a tube called a siphon. This expelling of air is what the octopus uses to propel itself.
An octopus has 3 hearts and light blue blood!
Octopuses are omnivores, feeding on both animal and vegetable substances. Their mouth is hard like a beak allowing them to tear their food and to crack invertebrate shells to get to the meat inside. Its favorite foods are crabs, mollusks and crayfish.
Octopuses hunt using stealth. They camouflage to match their surroundings waiting for their prey to swim or crawl by. The octopus will then reach out and grab it, secreting a venomous saliva (a nerve poison) that stuns its prey. Octopus venom is poisonous and in some cases can be fatal to humans. Most octopuses are nocturnal creatures therefore do most of their hunting and feeding at nights.
Octopuses are preyed upon by sharks, dolphins, morays and conger eels.
If an octopus becomes upset of frightened it may release ink to camouflage itself from potential predators. Watch this video to see how easy the ink made it for the octopus to disappear.
Another way they camouflage themselves is to adapt their color to that of their surroundings. Using a network of pigmented cells and specialized muscles, the common octopus can almost instantaneously match the colors, patterns, and even textures of its surroundings. It does this much the same way as a chameleon does to hide itself, but better, because an octopus can also change its shape.
Octopuses are considered the most intelligent of all invertebrates. Experiments show they have short- and long-term memory, that they can distinguish shapes and patterns, and that they may even possess observational learning.
Octopuses are able to mate because one arm of the male is modified into a sexual organ that deposits sperm in the mantle cavity of the female. The eggs are attached to a rock, where the female guards them until they hatch. The average litter size is 80 young.
As they hatch, the young octopuses swim to the surface and float with the plankton for a month or two. After that time, they swim back to the sea floor. Male octopuses die within a few months of mating. Female octopuses die soon after their eggs hatch.
An octopus is able to take care of itself, as you will see what happens when it encounters a 5 foot shark, in the following video.
Other Mollusk Articles by this Author:
Other Sealife Articles by this Author:
- Christmas Tree Worms - Colorful Ocean Sealife
A visual journey through the world of Christmas Tree Worms. Amazing photos and interesting facts make this a must see and read.
How to Prepare, Cook and Eat Octopus
Several comments have discussed the issue of preparing, cooking and eating octopus. If you are interested in this topic, visit this article: How to Prepare, Cook and Eat Octopus.
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