This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
Octopuses are amazing. In honor of World Oceans Day, here are eight facts about these incredible creatures.
8. Octopuses are masters of camouflage. However, research suggests that octopuses don't try to blend into their entire environment—to look like coral, sand and seaweed all at once. A study published last year found that octopuses, instead, picked a particular environmental feature—say a shell—and posed to look like it.
7. In addition to changing color to camouflage against a background, octopuses can also alter the texture of their skin. For example, an octopus that is trying to resemble kelp can use muscles under its skin to raise up papillae into seaweed-like ripples.
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6. Octopuses are voracious eaters. Many species enjoy hard-shelled seafood, such as crabs, clams and mussels. How to they crack open their lunch without claws? They can use their strong arms to try to tear apart shells. And if that doesn't work, they can drill in with their hard, spikey radula (like a toothed ribbon) and then suck their dinner out.
5. Underwater, octopuses can look quite coordinated and graceful. But octopus arms can move independently, without always having to take orders from the central brain. Each arm holds a host of neurons. And below the main brain is another neural network connecting the arms, allowing the limbs to coordinate tasks among one another.
4. Octopuses have such fine control of their eight flexible arms and hundreds of suckers that they can complete extremely delicate tasks. Laboratory researchers have found (often to their chagrin) that octopuses can remove any wires—and even surgical thread—that you put on them.
3. What these invertebrates lack in bone structure, they make up for with muscle. Some octopuses are capable of taking down big animals—including sharks. One giant Pacific octopus at the Seattle Aquarium was filmed killing a dogfish shark.
2. Octopuses canbe overfished. Females from most species lay thousands of eggs. These young often can mature and make their own babies within a year, making the octopus a resilient animal when disaster strikes or an environment changes. But many countries have overfished their octopus populations, leading to smaller catches—and smaller octopuses. Regulations in some areas, including closing fishing areas for a season and requiring octopus catches to be of a minimum mature size, have helped populations in Japan and Morocco, for example, rebound.
1. Octopuses are not impervious to climate change. Scientists are still working out how changes in water temperature and currents might affect octopuses, their prey—and their predators. And ocean acidification, which can weaken shells of some of their favorite prey, could have a big impact on octopus food availability. Although it might be a feast at first, with shelled animal population declines, octopus populations could be soon to follow.
Learn more about World Oceans Day and how to be a better ocean steward at the project's website.
Illustration courtesy of Ivan Phillipsen