One of my favourite things to see on a dive is an octopus - I could spend the whole dive just watching them in amazement at how they can change colours. Here are some fascinating facts about these marvellous creatures...
FACT: Octopi squirt ink to defend themselves.
Most species of octopusi can release a thick cloud of black ink that helps to confuse predators and provide the octopus an edge when attempting to escape. One of the pigments in the octopus' ink is melanin (the same pigment that gives our skin and hair color).
FACT: Special skin cells called chromatophores enable octopi to blend into their background.
Chromatophores enable an octopus to camouflage itself with its surroundings by changing the appearance of its epidermis.
FACT: There are three plural forms of the word octopus.
They include octopi, optopuses, and octopodes.
FACT: Octopi are cephalopods.
Cephalopods are a class of mollusc that includes squids, cuttlefish, nautilus, and octopi. Cephalopods are bilaterally symmetrical and have a head, arms, and in some cases, tentacles.
FACT: An octopus has three hearts.
Two hearts are used to pump blood to each of the octopus' lungs and the third pumps blood throughout the body.
FACT: Octopi have short lifespans.
Their lifespans vary among species but can be between six months and five years.
FACT: Octopi are highly intelligent.
They are believed to be the smartest of all invertebrates and show great skill at problem solving (instead of relying on instincts).
FACT: Octopi can fit into small crevices.
Since they have no internal or external shell or bones, they can manipulate their body to fit into tight spots.
FACT: Octopi move through the water either by crawling or by jet propulsion.
Octopuses are among the few animals that move by means of jet propulsion. Because jet propulsion requires much energy, many octopuses also crawl when moving more slowly. If an octopus needs to get away in a hurry, it uses jet propulsion by contracting their mantle and expelling a jet of water that propels them forward.
FACT: All varieties of octopus are venomous.
Fortunately, only a few species have enough venom to injure or kill a human being. Octopi inject their venom using a tough beak-like mouth that sticks out of the side of their head.
FACT: One arm of a male octopus is, well...special ;)
The third right arm, to be exact. At the tip of this “hectocotylus” arm is the ligula, which serves as its reproductive organ. In some species, the arm is visibly different since it has fewer suckers than the other seven arms.
FACT: An octopus sees the same thing upside down as right-side up.
The large and complex eyes of an octopus help it to perform the two functions most necessary for survival: finding food and avoiding trouble. Some species of octopus can squeeze through tight spaces only slightly larger than their eyes.
Oddly, an octopus’ eyes have horizontal pupils. What’s even more unusual is that the octopus’ eyes remain at the same orientation regardless of the creature’s position. So if it turns on its side or even upside down, the gaze of the eyes remain fixed in relation to the horizon.
...What’s more, a study published in the March 2008 edition of Marine and Freshwater Behaviour and Physiology describes a female octopus that attacked, suffocated, and spent two days eating a male who’d just mated with her 13 times over a 3.5-hour period. And you thought your significant other was needy!
