Common Octopus

Octopus Vulgaris, or otherwise known as the common octopus, is found mostly in shallow shore seas but can be found in depths up to 200 meters. They are found in tropical to subtropical waters around the world. They normally live to be between 12-18 months old. They are extremely solitary species. They begin their life by hatching from one of 100,000-500,000 very small sized eggs. Adults normally have a mantle around 25cm with tentacles up to a meter long, but most don’t make it to adulthood because they become food for other species before they can grow up. The common octopus is mostly nocturnal, but sometimes they can be found out hunting during the day. It is especially good at camouflage to the point where it is very difficult for scientists and predators to find them unless they move. One trick that scientists use to find them is by searching for their den. Outside of the den they will leave a pile of shells from the food they have eaten. This is called a midden, and it is much easier to find this midden than it is to find the octopus. Once the midden is found, the den will be located nearby. After the den is located, it is highly likely that the octopus is either inside or in the surrounding area hunting.

Predator and Prey:

The common octopus finds its prey by sensing movement, specific features, shape, or scent from the prey. They will feed on crabs, bivalves, and gastropods usually, but will also eat polychaetes and other crustaceans as well. The octopus is also prey to many predators though. Seals, Barracuda, and Eels are the main predators that feed on octopuses. Because of this, the common octopus has a few ways that they can avoid these predators. They have two main types of defense, a primary and a secondary defense.The primary is using crypsis, or in other words camouflage. The octopus can change its color to match the surrounding so that it can blend in better and become harder to see. It is believed that the octopus developed this ability through the evolutionary loss of its external shell. There are a few different structures of the skin that are responsible for the color change: the chromatophores, iridophores, and leucophores. The nerves in the brain of the octopus are also coated in chromatophores, allowing for it to control coloration patterning. Secondary defense is only used when the primary camouflage fails and the predator has spotted the octopus. These secondary behaviors include fleeing and inking, defensive postures, and deimatic behavior. Some examples of deimatic behavior are bluffing attacking the predator in hopes of startling it so the octopus can make an escape or scare it away. To do this, the octopus will shoot water at the predator or throw its arms at it.

Reproduction:

The common octopus has two separate sexes, male and female, and do not contain any hermaphrodites. Since it lives a very solitary lifestyle, there are no long-term pairings of the octopuses. After mating, the female will watch over the eggs very closely and once the eggs hatch, both the male and the female will die. One interesting fact about the mating is that the male keeps its sperm in certain sacs, called spermatophores, that it will then use one of its tentacles to insert into the females oviducal gland. The female will then store this sac in this gland until she reaches sexual maturity. She can actually store spermatophores from several different sexual partners until she reaches her sexual maturity and will choose which one she thinks is best to fertilize her eggs. Once the eggs are fertilized, she will lay them in her den and will spend the rest of her life caring for the eggs. She stops leaving the den and doesn’t even eat anymore. Once the eggs hatch she ends up dying.

Intelligence:

There have been a lot of studies done on cephalopod intelligence, specifically focusing on the common octopus in many of these studies. The octopus gaining this intelligence is interesting because unlike most other intelligent animals, octopuses are solitary creatures so they do not learn from other octopuses or their parents. One study that was done looked at how the common octopus can develop memory. A study was done that showed that an octopus can learn to avoid certain things. In this study, an octopus was in a tank and was feeding on crabs. Some of the crabs were marked with a square on top of them. Whenever the octopus would consume one of these crabs, the octopus would receive a shock. This octopus then learns to not attack in this situation the next time, showing that there is a memory system present. If presented the choice of attacking a crab with a square on it, the octopus can remember for 6 days or more to avoid this crab. Another study looked at observational learning in these octopuses. When an untrained octopus was placed where it could observe a trained octopus that had been trained to select a certain item when given the choice between two different items, the untrained octopus would then choose the same item when given the chance. There were no significant errors and this was shown to be a more efficient process of learning than conditioning the octopuses.

Overall, the common octopus is an extraordinary creature. From its incredible camouflage abilities to its high intelligence, it is a very interesting creature to learn about. And there is so much more that we have yet to understand about these creatures so it will be exciting to see what else we can learn from them.

References:

"A Memory System in Octopus Vulgaris Lamarck." A Memory System in Octopus Vulgaris Lamarck | Proceedings of the Royal Society of London B: Biological Sciences. N.p., n.d. Web. 02 Dec. 2016.

Fiorito, Graziano, and Pietro Scotto. "Observational Learning in Octopus Vulgaris." Http://search.proquest.com/openview/d4c6c6b2af1fdad0224500a39fcfa9d2/1?pq-origsite=gscholar. Science, n.d. Web.

"Octopus Vulgaris, the Common Octopus." Octopus Vulgaris, the Common Octopus - The Cephalopod Page. N.p., n.d. Web. 02 Dec. 2016.

Gilmore, Ryan, Robyn Crook, and Jacob L. Krans. "Cephalopod Camouflage: Cells and Organs of the Skin." Nature.com. Macmillan Publishers, n.d. Web. 02 Dec. 2016.

Case, Robin J. "Octopus Vulgaris." Animal Diversity Web. N.p., n.d. Web. 02 Dec. 2016.