Octopuses normally swim by pulsing their tentacles, like the bell of a jellyfish. This is quite energy efficient but it lacks acceleration, so when an octopus needs a sudden turn of speed it switches to jet propulsion.
To do this, they suck water into the mantle cavity and then squirt it at high pressure out of their siphon tube. This is the same way that they circulate water over theirgills, so the octopus is really taking a deep breath and then blowing out hard. The siphon is positioned on the side of the octopus’s body but it can be steered like the engines of a Harrier jet. Sometimes they use it as a boost when walking as well.
Top facts about octopuses
Fact – Octopus eye looks much like our own, with a lens and an iris but it evolved in a different way. Octopuses don’t have a blind spot where the optic nerve passes through, because the retina is positioned differently.
Fact – Poison glands – These evolved from salivary glands, and as well as paralyzing prey they also soften up the flesh, making it easier to eat.
Fact – Chromatophores – The colour-changing cells in the skin are funnel-shaped. By squeezing ink into the funnel from a bulb at the base, the octopus can control the size of the coloured dot.
Fact- Colouration – The octopus can change colour to match the sea bed or suddenly flash the bright blue rings to startle predators.
Fact – Intelligent legs – With the ability to twist in every direction, and suckers that can grip and release individually, octopus legs are much too complicated to be controlled from a central brain. Instead they operate semi-autonomously. An octopus is like a man holding a bunch of trained snakes; he issues instructions and trusts that they will be carried out, occasionally he has a look to make sure. This means that an octopus doesn’t have a very good idea of where its legs actually are at any moment and can’t work out the shape of something by feeling it, like we can.
Where can you find an octopus?
1.Coral reef – The myriad crevices in a reef are home to lots of tasty creatures but the octopus is very good at winkling them out.
2.Sandy floor -This is more dangerous for an octopus. Some dig burrows in the sand, others use discarded bivalve shells, like a hermit crab.
3.Rocky abyss – The giant North Pacific octopus lives in the deep, freezing depths of the Pacific seabed.