Octopus Teeth: The Tiny Chainsaw Inside an Octopus’ Mouth
Did you know octopuses come equipped with their own built-in “chainsaw”? YUP! Octopus teeth—Mother Nature really outdid herself on this one! These eight-armed wonders and their legendary relatives (think snails, slugs, and squids) have one ribbon-like tongue loaded with microscopic teeth called a radula. In cephalopods (octopuses, cuttlefish, squid, and nautilus), this radula basically revs up like a chainsaw, shredding dinner into bite-sized morsels before sending it straight down the hatch. Because these mini food processors are absurdly tiny, scientists cranked up the power on their microscopes to get a good look at all that toothy action!
7 Facts about Cephalopod Radulas
Ready to nerd out? Let’s zoom in and learn seven facts about cephalopod radulas—the toothy conveyor belts that turn snack time into a mechanized buffet line. And get this: their esophagus actually passes right through their donut-shaped brain!
Buckle up, OctoNation. It’s about to get wonderfully weird! 🦑 🥰 🐙
1. Cephalopod Teeth Have Special Names, Just Like Yours!
Pictured above is an opalescent inshore squid’s radula captured by a scanning electron microscope (SEM). Instead of light, it uses a beam of electrons to scope out every microscopic nook and cranny of this mini zesting tool, giving us an insanely detailed look at its shape and composition.
Because these teeny-tiny octopus teeth are smaller than a grain of rice, we break out the SEM scope to crank up the zoom—this particular shot is 75 times bigger than real life!
Just like we humans label our own pearly whites (think molars, incisors, and so on), cephalopods have their own tooth terminology!
You’ve got the rhachis (“RAY-kiss” if you want to impress your friends), the lateral teeth, and the marginal teeth—all with their own distinct shape. And guess what? Just like human dental records are unique, every cephalopod species has its own one-of-a-kind radula blueprint. By studying these differences, scientists can sort out who’s who in the cephalopod world, helping us keep track of biodiversity and conservation efforts.
Next time you’re snacking and chewing away, remember: somewhere in the ocean, a cephalopod is putting its radula to work—turning dinner into bite-sized morsels with a built-in, chainsaw—and we’ve got the electron-beam selfies to prove it!
2. What are Octopus Teeth Made Of?
Many people think the radula, the octopus’s toothy tongue, is made of keratin like our hair and nails. This misconception arises because keratin is a common and well-known fibrous structural protein found in many animals, including us humans! Check it…
Keratin forms hair, nails, feathers, and horns, so it’s easy to assume that other tough body parts are made of it too. But that’s not the case here! At OctoNation, we want to set the record straight: the radula is made of chitin, not keratin! (Oh, and it’s pronounced “KAI-tin”—’kai’ as in ‘kite’ and ‘tin’ as in ‘tin-can.’)
Chitin is a tough and flexible armor-like material found in crab shells, insect exoskeletons, and even the beaks of other cephalopods.
You see, the radula functions like a conveyor belt of tiny teeth, allowing octopuses to scrape, cut, and shred their food. Chitin’s toughness and flexibility ensure the radula is durable enough to handle hard shells and sharp enough to process soft prey.
the radula works like a mini cheese grater, letting octopuses scrape, slice, and shred their food. Chitin’s tough-but-bendy composition means this built-in grater can handle everything from hard shells (crabs, shrimp, bivalves) to softer bites (worms, fish, octopuses– yup, they’re cannibalistic)
While keratin is a protein, chitin is made of complex sugars, giving octopuses armor-plated like teeth! 🐙🛡️
Ok OK, their teeth aren’t actually armor, and the sugars in them aren’t the same as what we use to sweeten our coffee, But hey, chitin-based teeth are still pretty darn sweet in our book!
3. Octopus Feeding Tools: The Power Drill Function of the Salivary Papilla
Chainsaws aren’t the only power tool in an octopus’s arsenal (or should we say, tooth belt?). In addition to the radula, cephalopods rock a second toothy structure called the salivary papilla, which works like a power drill.
When an octopus tackles hard-shelled snacks like clams, it uses the salivary papilla to drill a neat little hole in the shell. Then it injects a venomous cocktail (toxins + enzymes) to relax and loosen the prey from its shelter. Think of the salivary papilla as a Swiss Army knife in the octopus’s tool kit—drilling, paralyzing, and opening things up so the radula can finish the job.
Check out the perfectly round “drill holes” a South Florida common octopus left in its prey below
4. The Crushing Power of Beaks
But wait, there’s more! Beyond the radula (“chainsaw”) and salivary papilla (“power drill”), cephalopods have a third feeding tool hidden up those many sleeves: a beak that looks a lot like a parrot’s. It’s also made of chitin—just like the radula—and it comes in two parts, an upper and lower beak. These built-in nutcrackers are perfect for crushing tough shells (think clams, mussels, and crabs).
Wanna see it in action? Check out this video of OctoNation’s scientific advisor, Dr. Chelsea Bennice, breaking down the octopus beak’s mechanics!
Feast your eyes on these high-tech snapshots below: they’re computerized tomography (CT) scans of an opalescent inshore squid (Doryteuthis opalescens) beak. You might recognize CT scans from the doctor’s office, but marine biologists love them too—because who wouldn’t want a super-detailed peek at squid beak? With CT scanning, we can see every nook, cranny, and sharp edge of the beak in incredible detail, giving us a front-row seat to how these undersea acrobats bite, chomp, and thrive in their watery world!
Check out the image above: that’s the upper beak in blue, while the bottom image shows the lower beak in green. Notice that long “wing” on the lower beak? Scientists use the phrase—“long lower”—to remember that the lower beak has two extended wings on either side. With chompers like those, we’re pretty relieved we’re not on a cephalopod’s dinner menu!
5. Do Octopuses Lose Their Teeth?
Once we humans say goodbye to our baby teeth, we only get one permanent set to last a lifetime. But octopuses? They basically have an all-you-can-get tooth subscription plan! Yup, octopus teeth get replaced throughout their lifespan. In this SEM (scanning electron microscope) snapshot of a South Florida common octopus teeth, you can spot the central rhachis (RAY-kiss) teeth looking a little worn down.
Luckily, the chainsaw-like radula keeps inching forward like a mini conveyor belt, letting the subradular organ absorb those old, tired teeth.
Think of the subradular organ as a teeth recycling station in a cephalopod’s mouth. It sits just below the radula (that ribbon of tiny teeth), absorbing and dissolving old, worn-out teeth so new ones can keep on rolling in. Essentially, it’s the behind-the-scenes cleanup crew that makes the octopus’s continuous tooth replacement possible.
As octopuses continually lose old teeth and gain new teeth, the tooth fairy makes plenty of visits underwater to our eight-armed friends. You could say they are the tooth fairy’s favorite customer. 👼 🦷 😂
6. Why is it Called a Radula? How Octopuses Got their Scraping Teeth Name
Ever wonder how the radula scored such a “rad” name? It actually comes from the Latin word radere, a verb meaning “to scrape.” Initially, “radula” was used to describe tools like rasps—for example:
- Woodworking Rasps: Designed for carving and shaping wood.
- Farrier’s Rasps: Used by farriers (horse hoof specialists) to trim and shape horse hooves.
- Metalworking Files: Used in blacksmithing or general metal shaping. These files have rasp-like teeth for removing material quickly.
Basically, any tool labeled a “rasp” is a file with distinct, individually raised teeth, perfect for fast, rough shaping… or in the octopus’s case, for scraping dinner right out of its shell. 🐙 🦀
While we humans chew with an up-and-down motion, cephalopods take a different approach—think of it more like a toothy chainsaw in action. Their radula rasps across food, grinding it up in a truly mechanical fashion—ideal for rasping up all that meat off fish bones and those hard shelled entrées!
7. How Many Teeth Do Octopus Have?
With dozens of toothy rows, a radula can come equipped with hundreds of tiny teeth! Across each of these rows, cephalopods will have anywhere from 7-9 teeth, with 7 being common in octopuses. Below is a SEM image of a section of a south Florida common octopus’ radula.
In just this tiny section of the radula, we can spot 11 rows of octopus teeth (not counting the very top and bottom, where the rhachis teeth got cropped). With 7 teeth per row, that’s 77 jaw-some teeth right there! Some octopuses even pack over 100 teeth in their mini “chainsaw,” giving them plenty of slicing power for whatever’s on the menu!
There you have it, Nation! Are your teeth chattering yet? Ours sure are. But, much like the radula scrapes up dinner, we’ve only scratched the surface of radulae facts. There is still much to learn about our octo-friends and their unique teeth.
That’s why OctoNation’s scientific advisor, Dr. Chelsea Bennice, along with her graduate student, Colleen Hecker, have been hard at work in the Florida Atlantic University High School Owls Imaging Lab—getting up-close and personal with octopus and squid radulae. Their research will keep unveiling more mind-blowing facts, so stay tuned for future rad(ula) revelations!
PS: “Radula” is singular—just one scraping tongue.
“Radulae” is plural—when you’re talking about more than one of these toothy wonders.
Think of it like “octopus” vs. “octopuses” (or “octopodes,” if you want to get fancy). If there’s one radula, you say “radula”; if you’re geeking out about multiple specimens, it’s “radulae.”
Acknowledgements: Radulae and beak images were produced using the JEOL JCM-6000 Plus Neoscope – Scanning Electron Microscope and Bruker SkyScan 1173 – Benchtop Micro CT scanner, respectively, at the Florida Atlantic University High School Owls Imaging Lab (RRID:SCR_023805). Jamie Knaub instructed the author in use of the scanning electron microscope and produced the CT scanned images seen herein.
Citations
- Huxley, T. H. (1853). II. On the morphology of the Cephalous Mollusca, as illustrated by the anatomy of certain Heteropoda and pteropoda collected during the voyage of H. M. S. “Rattlesnake” in 1846-50. Philosophical Transactions of the Royal Society of London, 143(143), 29–65. https://doi.org/10.1098/rstl.1853.0002
- Shimek, Ronald; Steiner, Gerhard (1997). “Chapter 6”. Microscopic anatomy of invertebrates. Vol. 6B: Mollusca II. Wiley-Liss, Inc. p. 748.
- Nixon, M. (1980). The salivary papilla of octopus as an accessory radula for drilling shells. Journal of Zoology, 190(1), 53–57. https://doi.org/10.1111/j.1469-7998.1980.tb01422.x
- Messenger J. B. and Young J. Z. (1999). The radular apparatus of cephalopods. Phil. Trans. R. Soc. Lond. B354161–182 http://doi.org/10.1098/rstb.1999.0369
Colleen Hecker is a master’s student in the Biological Sciences program at Florida Atlantic University. Her research involves using genetics and morphology to study the taxonomy and phylogeny of commercially important cryptic octopus species in South Florida. When she is not in the lab, Colleen enjoys SCUBA diving, playing with her cats, caring for her freshwater aquariums, and volunteering with The Sea Turtle Conservation League of Singer Island.
