Most carnivores have teeth to grasp and eat prey, so marine animals with teeth are not uncommon. Sharks, dolphins, eels, whales, many fish species, and marine mammals like seals and sea lions have teeth. Octopuses are opportunistic carnivores, with fish, lobster, crab, shrimp, clams, mussels, marine mollusks, and even other octopuses making up their diet. So, do octopuses also have teeth? As strange as it may seem, octopuses do have teeth. Find out more about octopus biology and learn how they use their specialized teeth in the initial stages of food processing.
Octopus Biology
Octopuses lack a mouth, throat, and teeth as humans know them. However, they possess two specialized, tooth-like organs—the salivary papilla and the radula—that enable them to consume hard-shelled prey. Feeding is facilitated by the buccal mass, a muscular structure located on the underside of the body, in front of the brain, within a cavity formed where the bases of the arms meet. The buccal mass houses the beak, salivary glands, radula, and their respective support structures.
The Beak
The upper beak of an octopus is shown on the right, and the lower beak is on the left.
©iStock.com/Ian_Redding
Octopuses have hard, parrot-like beaks made of chitin, a biopolymer found in the exoskeletons of crustaceans and insects. There are some variations in shape based on species, but all beaks are composed of an upper and a lower segment. Octopuses don’t have jawbones, so the segments are embedded in strong mandibular muscle tissue that connects the upper and lower beaks and controls their movement. They use their sharp beaks to crack shells and bite prey.
Salivary Glands
Behind the buccal mass lie anterior and posterior salivary glands and the salivary papilla. The anterior salivary glands secrete proteins. The posterior salivary glands store and secrete neurotoxins, as well as enzymes that aid in digestion. These glands work together to paralyze prey and break down proteins and chitin in hard-shelled organisms. The salivary papilla is a muscular structure covered in tiny teeth. This structure drills holes in shells and also delivers the venom from the salivary glands.
The Radula
Rows of radular teeth scrape across hard-shelled prey, grinding it down.
©The Freshwater and Marine Image Bank at the University of Washington / Public Domain – Original / License
The radula is a tongue-like organ studded with rows of tiny, chitinous teeth called radular teeth. There may be over 100 teeth on the radula, arranged in transverse rows, one behind the other. The primary row of teeth is called the central rachis. The lateral teeth are located on the sides of the central rachis, with the marginal teeth found at the outer edges of the radular rows. Researchers have noted that the radula is like a chainsaw or rasp, scraping across the surface of hard-shelled prey and grinding it down for digestion.
The Octopus Feeding Process
First, the octopus uses the suckers on its arms to catch prey and bring it toward the buccal mass. Then, the teeth on the salivary papilla help to excavate a hole in the shell. Next, the salivary papilla injects venom from the salivary glands into the hole. The beak may also be used to crush tough shells, creating an access point for toxin injection. The toxins immobilize the prey and relax its muscles, making it easier to extract from the shell. Finally, the radular teeth scrape and shred the prey, raking food particles into the esophagus.
Octopus Baby Teeth
The buccal mass on this baby octopus is the white circle with the small black dot, or beak, in the center of the tentacles.
©iStock.com/4kodiak
The buccal mass and all of its components, including the radular teeth, are present when baby octopuses hatch. However, octopus teeth continue to be replaced throughout their lifespan. The radula continually moves forward like an assembly line, with new teeth replacing older ones that become worn down. As a result, the radular teeth always remain sharp. Cells in the subradular organ dissolve the old teeth and membranes, which are absorbed back into the body.
Unlike humans, who have permanent teeth of the same size throughout their lives, scientists can estimate the size and approximate age of an octopus by examining the length of the radula, the width of the base of the six proximal and distal rachis teeth, and the total number of teeth. Just as dental records are unique to humans, radular structures can be unique to octopus species, helping scientists distinguish between similar species.
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