Males have fewer suction cups because the tip of their third right arm functions as a reproductive organ. Giant Pacific octopus mothers sacrifice their lives after laying their eggs in deep-water dens.
They live with their eggs for up to seven months without eating, ensuring that streams of oxygen- and nutrient-rich water waft over them. Mothers usually die after their broods hatch. This story has been corrected to say that an octopus has arms, not tentacles.
Sections U. So no octopi, octopodes or octopussies, Harmon Courage points out. Delicious tentacles? Photo by Paul Asman and Jill Lenoble.
As a result, the arms can problem solve how to open a shellfish while their owners are busy doing something else, like checking out a cave for more edible goodies. In one experiment, severed arms jerked away in pain when researchers pinched them. The ink also physically harms enemies. It contains a compound called tyrosinase , which, in humans, helps to control the production of the natural pigment melanin. The defensive concoction is so potent, in fact, that octopuses that do not escape their own ink cloud can die.
Scientists even suspect that the mimic octopus selects a creature to impersonate based on what's living in the area, choosing one that represents the greatest threat to its potential predator. When a mimic octopus was attacked by territorial damselfishes, for example, it disguised itself as one of their predators, a banded sea snake.
In , researchers reported another cunning solution for moving away from danger without breaking the camouflage illusion: walking away on two legs well, arms. In the first example of bipedal locomotion under the sea, two tropical octopuses were found to lift up six of their arms and walk backwards on the other two.
This allowed the algae octopus Abdopus aculeatus to keep its other arms extended and maintain its appearance of algae even while moving. Meanwhile, the veined octopus Amphioctopus marginatus walked with six of its arms curled under its body, possibly to appear like a coconut rolling along the seafloor. Both were able to move faster than their usual many-armed crawl. Take a look at the unusual locomotion in this SciFri video featuring researcher Dr Christine Huffard:.
But in , scientists made a surprising discovery in Jervis Bay, Australia: the supposedly solitary gloomy octopus Octopus tetricus actually builds underwater cities. Congregations of dens are formed from rock outcrops and discarded piles of shells from the clams and scallops the octopuses had feasted on.
Population sizes certainly aren't up to London standards, with only around 15 occupants living in Octopolis, as it was dubbed, and Octlantis - a second, nearby octopus commune studied in But they are far higher than scientists anticipated based on the loner reputation of O.
City living has its advantages and drawbacks, as we all know. Frequent aggression, chases and even den evictions were observed among the octopuses living at Octlantis. The researchers say they're not sure what the benefits of living in a densely populated settlement are for these octopuses, but it may just be a case of necessity, with limited den spaces available in the otherwise flat and featureless area.
Well, the blue blood is because the protein, haemocyanin, which carries oxygen around the octopus's body, contains copper rather than iron like we have in our own haemoglobin. The copper-based protein is more efficient at transporting oxygen molecules in cold and low-oxygen conditions, so is ideal for life in the ocean.
If the blood called haemolymph in invertebrates becomes deoxygenated - when the animal dies, for example - it loses its blue colour and turns clear instead. An octopus's three hearts have slightly different roles. One heart circulates blood around the body, while the other two pump it past the gills, to pick up oxygen. Discover where the real world and the Wizarding World intertwine, and how the wonders of the natural world have inspired myths, legends and magical creatures for generations.
Brimming with enthusiasm for the natural world, even Charles Darwin didn't always get it right. Curator Jon Ablett tells the tale of how an elusive monster from the deep came to be one of our popular attractions. Coral reefs attract deadly predators. Find out how their inhabitants survive using everything from camouflage to chemical warfare.
Get email updates about our news, science, exhibitions, events, products, services and fundraising activities. You must be over the age of Privacy notice. Smart cookie preferences. Change cookie preferences Accept all cookies. Skip to content. Read later. You don't have any saved articles. By Lisa Hendry. More than one brain It's a well-known fact that octopuses have eight arms. Giant Pacific octopus mothers sacrifice their lives after laying their eggs in deep-water dens. They live with their eggs for up to seven months without eating, ensuring that streams of oxygen- and nutrient-rich water waft over them.
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