- The octopus vulgaris is a mollusc with eight tentacles and a beak shaped mouth.
- Their tentacles can grow up to a meter in length.
- They live for between 12 to 18 months.
- The species is important commercially and is eaten around the world.
- They can walk using their tentacles or propel themselves along by forcing water through their mantle.
- They are able to change color dynamically and have a variety of patterns they can use to camouflage themselves against their surroundings, as in the following video:
- For defense they have an ink sack and can pump this into the water to confuse prey while making their escape.
- They have two different types of ink they can use. One is very thin and masks the octopus both visually and has chemicals which mask its smell. The other type of ink solidifies and partially resembles an octopus which confuses a predator.
- They are found in most tropical oceans from the shallows to 200 meters.
- When not out feeding they will secrete themselves in a hole in the rocks or reef often having a favorite hole. Scientists use these holes for research as the octopus deposits a pile of non digestible parts of its prey in a midden pile and these give a good idea of what species there are in the area.
- There are rows of suckers on each tentacle that can be used to attach onto prey or to hold itself onto substrate.
- They have a powerful nerve poison in their saliva that is used to paralyze their prey.
- They hunt at dusk and prefer crayfish and bivalve mollusks but will eat almost anything they can catch including fish which they snare with their tentacles.
- They have three hearts that are used to pump their blue-green blood containing hemocyanin around their circulatory system.
- Their kidneys are those of the mollusk, which operates differently to that of humans being having an appendage attached to each heart which filters the blood into a pair of kidney sacs.
- The common octopus does not have a constant temperature, instead it takes on the ambient temperature. It’s temperature control mechanism is to relocate to a warmer or colder area.
- They have a relatively high brain to body mass ratio and in experiments have learnt to open a screw type bottle top.
- Their lack of a skeleton allows them to fit through extremely small holes, as in the following video:
- The octopus vulgaris tends to mate when the temperatures are ideal for them.
- They are solitary animals and there is no long term pairing.
- The males have a modified third right arm which has a groove in it that is used to put a sperm sack in a specialized pouch that the female has.
- The female can store these sperm sacks for up to two thirds of their life and choose which male she wishes to mate with.
- Once she decides to fertilize her eggs these are laid in the substrate inside her den and she stops eating and grooms the eggs. Here’s a video of a female with her hatchlings:
- Once the eggs hatch the female dies.
An entertaining and informational video about octopuses:
- Aquarists who put live rock into their tanks, unknowingly containing a tiny octopus, will eventually notice their fish going missing as the octopus grows.
- A common octupus named Paul at an aquarium in Germany managed an 85% success rate when predicting football matches in the 2010 World cup by choosing boxes with team flags on them for upcoming matches. Experts believe this may be pure luck!