Here are several interesting facts about the common octopus (octopus vulgaris):
- 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 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!