We are finally talking about octopuses. Octopuses are definitely in the top three of my favorite animals, so I’m more than excited. I’ve even got an octopus tattooed on my arm because I love them so much. Between the vampire squid from hell and cute little Dumbo-eared octopuses, there is a lot to talk about, so let’s dive in.
First, as always, let’s quickly figure out where we are on the tree of life. If you get lost, make sure to watch the previous episodes of the series. (No worries, the first six will soon also be available in a video format. For now, they are audio-only, but I’ve already recorded the first two again, so they’ll be there soon.)
We covered the bacteria stuff and a bunch of little shit, skipped the plants and fungi—though we will get back to them—for now to reach the animals. We covered cool groups like the sponges, corals, sea jellies, and the like, to reach the bilateral animals, so animals with two symmetrical halves.
We covered most of the mollusks by now. Snails and slugs, clams, mussels and oysters, all covered. Currently, we are talking about the cephalopods, with only the octopuses left.
There are only two living, extant, groups of cephalopods: the ones with a shell and the ones without a shell. The shelled ones, the Nautiloidea, were the first of the group with the freaky cool nautiluses and allonautiluses. We then started talking about the shell-less ones, the Coleoidea, covering the squid and cuttles, as well as the bobtails and the currently unsorted Idiosepia, the pygmy squids that aren’t squids, and the very small group of the Spirulina with the Ram’s Horn Squid that also isn’t a squid. Stellar naming, as always.
And with that, we’ve reached the wonderful world of the eight-armed coleoids. You might remember that the coleoids are divided into eight-limbed and ten-limbed. Nautiloids, squids, cuttles, bobtails, all the ones we covered so far belonged to the ten-limbed decapodiformes. Today, we’ll cover the final group of the cephalopods: the octopodiformes.
Within the octopodiformes, there are two groups: the octopuses—squeal!—and the vampire squid. As you’ve probably guessed, the vampire squids are yet another example of a group called squid that isn’t a squid.
Those of you who love octopuses are probably sick of hearing about this, but as there are still so many people out there who don’t know better, let’s briefly talk about the correct plural: It’s octopuses. There, you are welcome. Don’t believe me? Well, I could tell you all about the origin of the word, quite a few misunderstandings, and weird people, but I won’t. You’ll forget the details within minutes anyway. If you do care, please let me know, and I’ll explain it at some point.
Speaking of names, the vampire squid actually takes that price. There is only one living species of Vampyromorpha, the vampire squid. Not only is it not a squid but it’s binomial, so taxonomic, name is Vampyroteuthis infernalis. Vampyro is, you guessed it, vampire. We learned that teuthology is the study of squid, so teuthis is a “squid.” Vampire squid. The really fun part is the infernalis. Inferno? Hell? Yep. It’s the vampire squid from hell. I love it.
Let’s actually start with this lovely creature from hell. I don’t know why you’d call them hellish. To me, these things just look cute. But maybe that’s because I love squid and octopuses so much that something that looks like a mix in between makes me smile. The vampire thing, okay, maybe. The dark-red color kinda looks like it could belong in a bad Dracula movie. Their mantle, so the body, looks kinda like that of a squid. An egg-shaped thing, but instead of the squid’s swimming fins, it has two floppy little fins that look like Dumbo ears. Their ginormous round blueish-black eyes sit close to their arms, between which they have webbing. When they get scared, they actually go into pineapple mode, which means that they invert their umbrella-like arms over their mantle. Cute! Okay, to be fair, the spikes along their arms aren’t that cute, but I stick with it. Cute!
But that’s not all the cool things about these vampires, which by the way don’t suck blood nor live forever. They usually feed on plant matter and detritus, anything that sinks from the surface, the marine snow. Yep, that’s snow made of the flaky remains of dead fish, whale poop, dead phytoplankton, and anything else that falls apart and sinks. In other words, they are detritivores. Very dangerous, right?
These cuties are usually found at deeper depths of 500 to a whooping 3,000 meters, and are one of the best-suited for life in the shitty conditions of oxygen-minimum zones, so areas with very little oxygen. They can suppress their aerobic, so oxygen-related, metabolism. A study by Hoving and Robinson showed that they also have a special protein that’s fucking good at attracting and binding to oxygen.
Okay, now to something that actually looks a little freaky: they have cirri. You might remember those from the nautiluses. Okay, so, the vampire squid has eight arms connected by webbing that makes them look like they are wearing an umbrella as a skirt. That should be weird enough, right? No, they have cirri, too. Each arm has 21 suckers in a row and multiple of these “finger-like projections called cirri.” Their cirri are in a pocket between the first and second arm, so in the front, and can extend up to five times the body length. There are octopuses that have these cirri, too, by the way. We’ll get there.
So, to feed, they detect it with the cirri, transfer it to the arms where they wrap it in mucus they secrete from their suckers—which by the way suck at sucking—and then move it toward the beak. In addition, they let detritus accumulate on their arms and then wipe that toward their mouth with a good serving of mucus. Yum! Still, not dangerous. You aren’t detritus. Also, they are usually only about a foot, 30 centimeters, long. They really aren’t scary.
A final really cool thing about vampire squids is that they can bioluminesce. Remember the bobtails with their light organs? Yeah, these things have glow-in-the-dark “ink.” When other cephalopods would ink out dark clouds, these darkness-dwellers ink out glowing clouds. I mean, to be fair, a dark cloud in darkness might just not do the trick.
We don’t know enough yet, but they might also be using bioluminescence for communication. They can make the tips of each arm light up. But considering there are so few of these vampires, and they rarely encounter each other, this is hard to study. Thus, they usually take any chance they get to mate, and females actually store the sperm for months before fertilizing the eggs. And that’s despite the fact that vampire squids, unlike the other coleoids, actually have more than one reproductive cycle.
The fancy term for more than one reproductive cycle is iteroparity. Itero- sounds like iterations, so multiple cycles, so that makes sense. Octopuses, almost all squid, cuttles, and bobtails, as well as the smaller groups we’ve talked about are all semelparous. Semelparous means that they only have one reproductive cycle. Vampire squids seem to go through at least a monthly cycle, with a dormant, resting stage between each reproductive cycle. The exact length of the resting stage isn’t known yet. But scientist think that their low metabolic rates lead to these significant resting periods of at least a month in between. Scientists think they reproduce about 20 times over their lifetime and release between 6,000 and 20,000 eggs. Quite a lot of potential offspring. We aren’t certain how long exactly that lifetime is, but we think it’s somewhere around a decade. If you are better at math than me, you’ll have noticed that they don’t actually reproduce every month, even if they’d be able to. I assume this is due to them not even finding a male every month. Or it’s just too exhausting. Both sound totally valid to me.
If they do reproduce, the male transfers a sperm packet into the female’s mantle, much like how we discussed for the squid and some cuttles, and the female then holds on to that sperm until she decides it’s time. She releases the eggs in small clusters that then float around until they hatch—or get eaten.
And then you’ve got tiny vampire squids in the water. That sounds even cuter. I know chances of me ever seeing one are slim to nonexistent, but that doesn’t keep me from loving these creatures. Vampire squid are cool, even though they are neither vampire nor squid.
And with that, it’s time to move on to the Octopoda, the octopuses. Yay! Finally! Did you know that octopuses are apparently also called devil fish? So, after the vampire squid from hell, we’re now talking about devils. Interesting how misunderstood these animals are.
There are between 300 and 400 species of octopuses. They are divided over the two major groups, cirrata and incirrata, which are the octopuses with and without cirri. So, like the vampire squid we just talked about, some octopuses have pockets with cirri between their arms. In general, they share a lot with the vampire squid when it comes to looks. They are stout and cute, with those dumbo-ear fins and webbing that reaches to the end of their arms like an umbrella. They are also far too cute to be real. They are kinda the atypical octopuses, not following that typical body plan we are used to.
There are quite a few groups of octopus—way too many to cover all—so those two divisions are as deep as we’ll take it. Instead, I want to tell you a lot about octopuses in general, and then talk about some species examples like the California Two-Spot inked onto my arm. I’m sure we’ll return to some of those octopuses in species-focused episodes later down the road.
Octopuses can be found almost anywhere in our oceans, from shallow tide pools to the deepest depths. Ironically, my favorite animal exists almost anywhere, but not where I live. The Baltic Sea on Germany’s Northeastern shore has a lower salinity that doesn’t support most cephalopods. Scientists think the Baltic will get more and more suitable for cephalopods as climate change progresses, so there’s one good thing about climate change for those living around the Baltic, I guess.
But, as we are in our Tree of Life series, I don’t get to fall into doom and gloom, so we’ll move on to me getting overly excited about everything octopus.
As octopodiformes, you probably already guessed that octopuses have eight limbs—which you probably already knew before. They have eight arms—though some people prefer talking about six arms and two legs, but that is semantics. Like the rest of the cephalopods, they have a mantle, their body, a funnel or siphon which they can use for jet propulsion but also for breathing oxygen-rich water past their gills, and a beak. Behind the beak is the characteristic radula, the raspy tongue. Their arms are covered in suckers (though they can be adapted to look very different, especially in the cirrata).
Like the other cephalopods, they have a closed circulatory system. Octopuses also share the three hearts of the squid and cuttles. A systemic heart that pumps blood through their body, plus two gill hearts that pump blood past the gills. Apparently, their systemic heart is known to skip a beat here or there, and even stop for a while if they use jet propulsion. Also, if they rest, the systemic heart may stop to preserve energy while the gill hearts maintain the now low blood flow. Interesting!
Speaking of jet propulsion: Octopuses, like other cephalopods, have a siphon or funnel. They use this to jet around quickly. I should probably mention that the cirrate octopuses can’t do this and can only use the fins and webbing for movement. Anyway, back to the more typical octopuses:
As I said, octopuses can’t keep jet propulsion up for long, as their systemic heart can’t keep pumping properly while the mantle pressure is all messed up from jetting around. They also use the siphon for breathing. They draw water in through the gills, past the gill lamellas, where oxygen is extracted from the water and absorbed into the blood. They then expel the water through their siphon. And, to make octopuses even cooler, they can breathe through their skin. While many organisms can take up oxygen through their skin, I think it’s pretty impressive that this is actually a huge part of breathing for octopuses. While they sit around, a scientist named Wells estimates it to be around 41%. While they swim, it’s likely still around a third. But, to accomplish this, the octopus needs water flow, so if they curl up in a tight den, this number goes down to as little as 3%.
The fact that their heart can’t keep up with jet propulsion is probably also why octopuses only jet around if they need to make a quick escape. They can use their entire body to move by kinda waving it up and down, similar to a human doing a dolphin-style swim. Otherwise, they prefer to move along the bottom with their arms, pushing and pulling along. I get it. The idea of a heart stopping every time I run is scary as shit. I know, they’ve got two backups, but they are not full replacements.
You know how humans say that their heart skips a beat when they see their partner for the first time? Well, octopuses take that one almost literally. The male’s heart skips beats in preparation for copulation. He uses his adapted arm with the so-called hectocotylus to reach into his mantle and pack up the sperm from his penis (it’s called a terminal organ) into a neatly packed spermatophore which he then inserts into the proper place on the female's mantle.
Octopuses, just like most squid and cuttles, are semelparous, so only mate once before they go into senescence and die, so they only get to do this once. Well, technically, it’s apparently possible for the female to mate again shortly after the first time, as some scientists assume a male can remove the spermatophore of a competitor before inserting his own. But either way: they only get to reproduce once, no matter if the female in the end carries those babies. We still don’t fully understand what sets off this wasting away. Researchers have studied California Two-Spots, and it looks like the optic gland shifts the cholesterol metabolism, which leads to quite a shift in hormones. And if you think this is all peaceful. Some females actually speed along the dying process by twisting their arms into a tangled mess.
The female carries the eggs for a few weeks before laying them in strings. She protects them for as long as she can, her final act. The male dies a few weeks after donating his sperm, while the female uses the last of her energy to blow oxygen across the eggs and guard them. But she, too, enters senescence, that state of falling apart, after she lays her eggs, and doesn’t eat again. She’s slowly dying while she protects her eggs.
A diver in Florida followed one such octomom, as he called her, every weekend, and got some really cool photos of the eggs with the little octobabies inside. I reached out to him, and he gave me permission to share them with you.
How long the eggs take to hatch depends on the species. Warmer-water species live less long, mate younger, and have shorter hatching times than cold-water species. Some deep-water species take more than a year to hatch, others don’t even live that long. In 2007, Bruce Robison and his colleagues started monitoring a deep-water octopus mom who ended up guarding her eggs for 53 months, so 4.5 years. Considering even larger species like the Giant Pacific Octopus only get to 3-5 years, that’s a very long time. Remember, they don’t eat while they watch their eggs, so this mom survived 4.5 years without food. That’s only possible because of the very cold conditions down in the deep, which leads to a very slow metabolism. But they also wrote that the got smaller, lost the texture of her skin and her pigmentation during this time, so she was rotting in place, just very slowly.
Let’s move from that colorless, morbid topic to something more colorful: camouflage! Octopuses are capable of pretty much the same magic mindfuck camouflage as cuttles. The only reason I’m more impressed by cuttles is that cuttles are more restricted in their body shape because of the cuttlebone. Them blending in impresses me more than an animal that can fit through any hole their beak can fit through. But that doesn’t change the fact that octopus camouflage is fucking impressive.
Like most cuttles, most octopuses are thought to be colorblind and seem to make up for this by being able to see polarized light.
I’ve seen this display first-hand while diving around Catalina island and the other Channel Islands around Los Angeles. My favorite octopus, the California Two-Spot, Octopus bimaculoides, is very common in those waters, so I got quite a few chances to see them. Once, I hung out with a two-spot, enjoying some sunlight. Back then, I’d been told it was a sun octopus, but that’s nonsense. It was yet another beautiful bimaculoides.
Over time, I got rather good at spotting their dens.
You know, octopuses are super intelligent. They have a highly complex nervous system, with only part of it localized in the brain. The rest is spread out over the arms. They can even detach an arm, something called autotomy, which then keeps moving and distracts predators while the body swims away with the other arms still attached. The arms don’t grow back, but octopuses with an arm missing are seemingly totally capable of enjoying the rest of their life without much impediment. So, while octopuses have ink and use it to create smokescreens to distract predators, they have another card up their sleeve.
But, we were talking about camouflage. Octopuses, like cuttles, have special pigment cells called chromatophores that contain pigment in up to four different colors: orange, red, brown, and/or black. But, also like cuttles, they aren’t limited to these colors due to their reflective iridophores and leucophores. They can bend the light to show the color they need. I’ve seen green two-spots and completely white two-spots—well, technically I’ve seen one two-spot show all those colors in the span of seconds, going from brown to green to white to blend in with their surroundings.
And, keep in mind, they do all this not by copying their environment perfectly but by extracting the essential features to blend in. I won’t get into their eyes again, as we talked about cephalopod eyes in detail when we talked about the cuttles, but let me just remind you that their eyes are a lot like ours, just without the blind spot. You might remember from last time that you can distinguish a squid from a cuttle by the shape of their pupils. Well, it might make more sense to count the arms to figure out if something is an octopus, but if you insist: most octopuses have a square pupil, a bar from left to right. So, nautiluses have a comma, a line from top to bottom that is bigger at the top. But they’ve also got a shell, so that’s probably easier. Squid have a round pupil. Cuttles have a W-shaped pupil. And most octopuses have a square pupil.
While every single online source I could find says that octopuses have rectangular or square pupils, I’m pretty certain this doesn’t apply to all of them. I mean, just look at any of the deep-sea species, and they seem to have huge blobs of black or blue. I really tried to find more information on this, as well as the shape of the vampire squid pupil (which also looks round) but it’s impossible. The entire internet just seems to copy from each other or talk about a specific species of octopus as if it’s representative of all.
So, let’s move on. Their eyes are cool either way. But they have other senses that are fucking impressive as well. You all know that they have suckers. You’ve probably drawn pictures of octopuses in Kindergarten. These suckers are strong and dexterous. We humans like to boast about our opposing thumbs, but it’s nothing compared to the dexterity of octopuses with dozens of opposable suckers. And all that while being able to squeeze through the tightest holes—well, as long as the solid beak fits. And, they can’t just do a lot of shit with their suckers, the suckers also have chemoreceptors, so they can taste what they touch.
To steal a joke from John Oliver, who did a wonderful web special on octopuses that is more than worth watching: I’m really glad I can’t smell everything I have to touch.
There are probably a million cool things about octopuses I’m forgetting, but I think it’s still time to move on to some examples. I’m sure we’ll return to some of these wonderful creatures in species-focus episodes in the future.
The smallest octopus is likely the star-sucker pygmy octopus, Octopus wolfi. Seriously, star-sucker? That’s so cute! And so are these tiny things. They get to about 2.5 centimeters, so an inch, and weigh essentially nothing. A gram. I wanna see one! Their lifespan is about a year, and they are found in the Western Pacific. I guess I’ve gotta dive there more.
Another tiny one is the pygmy zebra octopus, O. chierchiae, which scientists are particularly fond of because they don’t immediately enter senescence when they start laying eggs but instead lay several clutches over their reproductive period. Poor little things might be a little too well-suited for scientific prodding and probing. They join other model organisms as the favorites for research.
My favorite, the California Two-Spots is also frequently kept in aquariums, something I, personally, don’t agree with, and in scientific studies. Their size and intelligence makes them interesting to keep, but they are also much easier to keep than the Giant Pacific, while living longer than the smaller species. Plus, proofing an aquarium for a two-spot is easier than for very small species, as the beak gets smaller in the smaller octopuses, so they can squeeze through even tinier holes.
I don’t think anyone should keep these immensely playful creatures in captivity, neither as a hobby nor for science, but I am usually called idealistic, especially with that latter view. I just don’t think everything should be excusable just because it’s for science and there might be beneficial knowledge for us humans in there. But that’s a topic for another day.
One of the largest, and probably one of the best-known species of octopuses is the Giant Pacific Octopus, Enteroctopus dofleini. Their life span is among the longest of the octopuses, but as we know, some deep-sea species get older due to the cold slowing down the metabolism. Giant Pacific Octopuses live, you guessed it, in the Pacific, but are also the species usually found at aquariums to entertain the public—with the octopus switched out every year or two, so the public doesn’t find out their beloved octopus has died. Not all aquariums do this, of course, but it’s pretty common. I recommend reading Soul of an Octopus, as she talks in depth about the Boston Aquarium and how they keep a second octopus behind the scenes. Excellent read!
Anyway, the GPO is a lot bigger than the star-sucker pygmy. They reach between 9 and 16 feet, so somewhere between 2.7 and 4.8 meters, and weigh in at 22 to 110 pounds, so 10 to 50 kg. But, according to National Geographic, we know of a specimen that was 30 feet across and weighed more than 600 pounds. Hard to believe. Fuck! The Giant Pacific Octopus can be found almost anywhere from shallow waters to really deep depths.
Now that we’ve covered the biggest and smallest, let’s talk about some really cool and special ones, before I close this up with my beloved two-spot.
The octopus with the weirdest name, at least the weirdest one I’ve encountered so far, is probably the Wunderpus photogenicus. Yes, wunderpus. The common name is wunderpus octopus. Wunder is German and means, you guessed it, wonder. And considering how pretty they are, it’s no wonder they are called photogenic. They have distinct roundish spots on their mantle and stripes along their arms. They are usually red or brown with white markings. They are frequently mixed up with another really cool species, the mimic octopus, Thaumoctopus mimicus, which looks rather similar but has a slightly different pattern. That one, by the way, likes to walk around on two legs while pretending to be algae with the rest of it’s body or taking the shape of a lion fish or eel. Freaky cool things! I told you octopuses are creative in their camouflage.
And then there’s the coconut octopus that uses shells as shelter. As you probably guessed from the name, it likes to use fallen coconut shells, but it’ll use anything it can find, using it’s many sucker-fingers to hold on to anything that can act as a shield.
Good defense! I love it. Also, effective is the defense of the Blue-Ringed octopuses, which are venomous enough to actually be dangerous to humans. I mean, most octopuses are venomous, but also most of them are not dangerous to us.
One bite of the blue-ringed octopus common in Australia can kill an adult human rapidly. According to a study in the Journal of Molecular Evolution, it’s by far not the only one, though. They say that all octopuses, cuttlefish, and some squid are venomous.
But, rest assured. Only the blue-ringed octopus is actually dangerous to humans. So unless you are on the menu of, for example, a Giant Pacific, it likely won’t hurt you. Octopuses are curious creatures, but they are also peaceful, gentle creatures. If they need to defend themselves, they can do quite a bit of harm to humans, but that’s not what they want to do. I still don’t recommend getting your fingers near their beaks. If they don’t like you, they might just bite, as one of the people in Soul of an Octopus found out. In the end, they found out the octopus didn’t like cigarettes. Can’t blame them.
Anyway, no matter how dangerous it might be, the blue-ringed octopuses, Haplochlaena, are pretty things. Vivid blue rings stand out beautifully against the brown or beige body. And if you provoke them, those rings turn iridescent blue, becoming even more beautiful. And no, I’m not saying you should provoke one. Venomous, remember?
And with that, we’ve reached my favorite octopus: the California Two-Spot. It might not look the most exciting. There are no fancy blue rings. It’s usually rather neutrally colored with brown or beige. The only distinguishing marks are two symmetrical spots, one on either side of the mantle. So, surprisingly, the Two-Spot has two spots. I mean, we’ve gotta get naming right some of the time.
But, the Two-Spot is part of why I am who I am today. We started scuba diving in 2018 when we lived in Los Angeles. And seeing the underwater world changed everything for me. Every time we went to the Catalina dive park, my husband had to suffer through me swimming to the sunken swim platform, where I knew an octopus had a den in one of the corners. And every time, I searched nooks and crannies for more octopuses—and usually found them.
The California Two-Spot lives to about two years old and is usually found in coastal waters that recreational divers can reach. They hang out between rocks or in structures. We’ve found them in old pipes, too.
In the waters off Catalina island, I got to see camouflage first hand, but I also saw how calm these creatures are. Unable to get deeper due to ear issues, I hung out with one of these for ten minutes. The Two-Spot got used to me, started extending tentacles to me, and while I had to leave before getting touched, it was a magical encounter that I will never forget.
And with that, I’ll let you go. I hope you learned something new today or rediscovered something you’d forgotten. Nature is fucking fascinating, and I love making these episodes.
But, these episodes are research intensive. Just scripting this episode took three days of work, and then there’s the editing, the uploading, and all that fun stuff. I love making this series. I learn new things with every episode and get deeper and deeper into topics I love.
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Until next time.
I study Marine Ecology at the University of Hamburg, so a lot of this knowledge comes from hours of research and sitting through lecture after lecture.
Going through the lecture slides from school is a process that involves a shit-ton of fact-checking, as a lot of what we learn is pretty outdated. So, all semester, I google things to death, read papers and essays, ask a million questions, and discuss things with friends and classmates.
Where the source isn’t our lecture slides or unidentifiable sources from hours of late-night knowledge hunts, I have linked them in the text.