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You know octopuses are strange creatures. They’ve always been part of our nightmares and scary stories, but that’s mainly because they look so odd. The more you know about them, the stranger they seem.
Eight Limbs
Tell me, O Octopus, I begs
Is those things arms, or is they legs?
I marvel at thee, Octopus;
If I were thou, I’d call me Us.
-Ogden Nash
We’ve only recently found the answer to this question. Octopuses have two legs and six arms. Good luck telling them apart, but the octopus knows! They tend to push off surfaces and crawl with the two limbs furthest back, and use the others to feed. The research originally meant to find if octopuses were right- or left-handed. They are neither, but many tend to use the third arm from the front, on both sides, for many tasks.
Muscles
This post was inspired by a conversation with my daughter about anatomy, in which she posited that without bones, we wouldn’t be able to move. The octopus has no skeletal system and still moves quite well. They crawl along surfaces with their legs and arms and swim by moving with wave action or by spurting water from its mantle cavity, which is used for respiration, but can also propel an octopus at up to 20 miles per hour in larger species. The octopus’ intricate muscular system plays a part in its other odd features: flexibility, suckers and camouflage ability. (image credit: Erica Simone)
Flexibility
There are advantages to having no skeleton. An octopus can squeeze through any opening larger than its beak, its only inflexible part. This allows an octopus to nestle inside crevices of any shape, as long at the volume is sufficient.
Camouflage
An octopus can change color at a moment’s notice. Faster than that, actually. Tiny pigment sacs called chromatophores with up to five colors lie beneath the skin. Rings of muscle control the release of pigment to match the terrain an octopus covers, or when it decides it must blend in with the background to fool predators. Can you spot the octopus in the left picture? Watch the video.
Suckers
Each sucker on an octopus tentacle has a ring of muscle that contracts when it must stick to a surface, creating a vacuum inside the seal. If a predator tries to pull it away, a “piston-like structure” inside pulls up and boosts the vacuum seal.
Beak
The only hard part of an octopus is its beak, which it uses for eating and defense. Until recently, scientists wondered how they used this one hard organ without hurting the other soft organs. Recovered beaks are composed of hard chitin, but beaks on a living squid have been observed to be very different. The chitin shows a gradual shift from unbreakably hard at the tip to softer material where it attaches to the muscles of the mouth. This gradation is believed to be present in an octopus’ beak as well as squid.
Ink
In addition to its many other defenses, an octopus produces ink made of natural red melanin. It appears a dark brown when concentrated. A squirt of ink can help camouflage an animal, or distract a predator while the octopus escapes. The ink also contains tyrosinase, which irritates a predator’s eyes. The few octopus species that don’t produce ink tend to live in deep water, where visibility is already low.
Intelligence
Octopuses are highly intelligent and can learn new tasks even as adults. The learning power of an octopus is only restricted by its short life span, which ranges from six months to a few years. They often manipulate their environment in ways that suggest playing in addition to regular life tasks. In captivity, they play with toys such a Rubik’s cube, and even have preferences like Louis, who is attached to a Mr. Potato Head.
Some octopus species are stranger than others. The blue-ringed octopus carries enough venom to kill ten people. The deep-sea finned octopus glows with a blue-green light. With 300 different species, they are the masters of survival in many ways.
Comments (18)
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Answers in Genesis?? Seriously? What a joke that last link is… “This light-emitting octopus is yet another example of exquisite design, so people are without excuse”..
So if something that complex was designed, then obviously the designer is at least equally complex, so who designed the designer?
posted by Adam Rechkemmer on 9-18-2008 at 10:39 am
What about the fact that they have 3 hearts, and blue blood (a copper, rather than iron, oxygen-bearing compound)?
Or that the eye of the octopus is one of the most developed of all undersea creatures, having (independently) evolved a design very similar to our own.
And the reason that they have these amazing eyes is because they do not have the requisite nerves in their limbs to feed back on activities, so need to watch their arms to know what they are doing.
All this information is processed by a brain shaped like a donut, the stomach being the contents of the hole.
What about the way they use a drill-like radula to hole the shells of crusteceans, inject digestive enzymes and suck out the pre-made crab soup?
Octopuses are amazing.
posted by Dai on 9-18-2008 at 10:45 am
I actually read (I think in National Geographic, and no I can’t find the article now) that some scientists believe that Octopus would be the dominate species on the planet (since 3/4 is covered in water) but were restricted because they only live a few years which keeps them from forming societies and pooling their intelligence.
posted by Kevin on 9-18-2008 at 10:57 am
Easily the most interesting article I’ve read in the last six months!
posted by bzzyb on 9-18-2008 at 11:19 am
So is an octopus born from an egg or live? And are they multiple or single births? I can’t say I’ve ever seen a nature show about how they reproduce.
posted by Tricia on 9-18-2008 at 11:36 am
Adam, I didn’t even notice where that link came from, so I’ve now replaced it with something more appropriate. I collected so much information, and the bioluminescence was under the “extra” list.
posted by Miss Cellania on 9-18-2008 at 11:42 am
Tricia, they lay lots and lots of eggs. As Dai points out, you could fill books with all the oddness of octopuses!
posted by Miss Cellania on 9-18-2008 at 11:46 am
It’s always been my favorite sea creature, hands down.
posted by Johnny Cat on 9-18-2008 at 1:00 pm
Fascinating animal and blog! Kevin, that reminds me of Animal Planet’s “The Future Is Wild,” where gigantic land squids rule the earth. So grateful we’re not beneath them on the food chain…yet?
posted by pc on 9-19-2008 at 3:11 am
@tricia
It’s even cooler than that. After fertilisation, the female octopus lays hundreds of eggs, contained in cases that look like thick pasta. These eggs need to be continuously oxgenated, and this is done by the mother waving her arms over the cases, which are fastened to a rock or similar solid object at one end, usually in a secluded crevice.
The mother spends her whole time doing this, neglecting to eat, and eventually dies of hunger before her children hatch.
Even in the (translucent) eggs, the mini-octos have the colour-changing and bioluminescant skills of an adult. And they emerge as tiny, but completely viable and self-supporting, octopuses.
posted by Dai on 9-19-2008 at 6:43 am
Great article. Concise yet packed with info & great pics. I’ve always been fascinated by these critters – they’re worth a lifetime of study.
posted by Mary on 9-19-2008 at 7:36 am
Thanks to Miss Cellania and Dai for their info. Pretty cool animal that octopus.
posted by Tricia on 9-19-2008 at 8:20 am
I watched a documentary not too long ago about measuring the intelligence of an octopus (NatGeo maybe?)…it said that for all intensive purposes an octopus has as much intelligence as a dog. I’d like to see a dog play with a Rubix cube!
I’ve said many times that if I had gone into marine biology I would have definitely focused my research on the octopus. They’re absolutely fascinating!
posted by bas on 9-19-2008 at 9:24 am
Funky critters! I´ve never really been interested in octos but their extreme weirdness has just placed them on my “interests” radar.
posted by GTT on 9-19-2008 at 11:27 am
Miss Cellania, I’m curious to know why you thought your original link was inappropriate.
posted by Caleb on 9-19-2008 at 1:46 pm
Because someone complained about it, and I realized I hadn’t read it all the way through. It was faster to find a secular site than to scrutinize it further.
posted by Miss Cellania on 9-19-2008 at 1:55 pm
The ink changing video you link to has been removed from YouTube.
posted by Zoasterboy on 9-19-2008 at 10:18 pm
Thanks for the heads up, Zoasterboy! I found another copy of the same thing.
posted by Miss Cellania on 9-19-2008 at 10:51 pm