You can tell a lot about sharks simply by looking at their teeth – revealing their diets and, by extension, their lifestyles. While public perception about sharks is often quite negative, with their teeth viewed as "weapons", the reality is that, just like the teeth in our own omnivorous mouths, shark teeth are specialised for their diets, and by looking at them, scientists can tell what is on a shark's menu (it's not us).

(Cover image credit: Jean Tresfon)

If you want to learn more about shark teeth, check out our Shark Alley space at the Save Our Seas Foundation Shark Exhibit.

Let’s take a closer look at shark teeth and see what we can tell about the sharks that have them:

Needle-like Teeth

The sharp, pointy teeth of sharks like the ragged-tooth sharks in our Save Our Seas Foundation Shark Exhibit might look fearsome, but they actually tell us something quite important - this is a shark that eats slippery food, like fish. This style of tooth means that ragged-tooth sharks are unable to bite off pieces of their prey, so they tend to focus on prey that they are able to swallow in one bite.

Ragged-tooth sharks (Carcharias taurus) might have an appearance that humans perceive as fearsome, but that array of needle-like teeth is specifically adapted for catching slippery fish. Credit: Jean Tresfon

The diet of the ragged-tooth shark sometimes consists of fish that might be larger or stronger than what can be comfortably swallowed in one bite - so its teeth are curved to give it grip as it tries to thrash its food into pieces. Sharks that specifically focus on smaller prey tend to have straighter teeth.

Australia's spotted wobbegong (Orectolobus maculatus) has short, pointy teeth which help them keep a firm grip on slippery prey, but their short length reduces the risk of accidental breakage or snagging if the wobbegong opportunistically eats a hard-bodied prey, like a lobster, in addition to its usual slippery died of octopuses and fish. Credit: Richard Ling [CC BY-NC-ND 2.0]

This type of shark tooth serves a similar function to your own canine teeth!

Saw-like Teeth

Sharks that specialise in hunting large prey, particularly marine mammals like seals, usually have a combination of pointed teeth on their lower jaw, with asymmetrical triangular teeth in their upper jaws. This tooth combination allow these sharks to bit off pieces of their prey, enabling them to consume prey larger than other shark species, and allowing them to take advantage of carrion, like dead whales.

The image of a great white shark (Carcharodon carcharias) leaping from the water while humans taunt it with bait is ubiquitous, but rather than intimidating boat crews, great white sharks use this array of saw-like teeth to bite large prey, like seals, into pieces. Sharks cannot chew like we humans can, so cutting their food into chunks that can be swallowed whole is essential. Credit: Bernard Dupont [CC BY-SA 2.0]

Many sharks with this tooth type have serrated upper teeth. The most extreme example of this is the tiger shark, which has hooked teeth that are sharp and serrated enough to bite through sea turtle shells.

Tiger sharks (Galeocerdo cuvier) have uniquely curved and serrated teeth that allow them to cut through bone and shells - making them one of the few sharks able to predate on adult sea turtles. Their ability to eat anything has earned them the reputation for being the "oceans garbage cans", with everything from discarded bicycles to dumped animal carcasses being found in their diets. Credit: Stefan Kühn [CC BY-SA 3.0]

This cutting action is similar to how humans use their front incisor teeth.

Grinding Teeth

Many sharks prey on hard-shelled animals, like molluscs, crustaceans and worms. These sharks sacrifice sharp teeth for pavements of broad, flattened teeth that are ideal for grinding up hard shells. 

The nurse shark (Ginglymostoma cirratum) uses a combination of grinding teeth and suction to eat a wide variety of hard-bodies animals, as well as small fish. Credit: Steven Laycock [CC BY-SA 4.0]

This arrangement of flattened teeth are similar in purpose to human molars (although ours don't grow back if we try to bite something too hard).

Other teeth

The above categorisation is a simplification, with each of the 500 known species of shark having its own unique combination of tooth features. Many are specifically adapted to unique feeding strategies - from carrion-eating scavengers to giant filter-feeders that have no need for teeth at all! Here are a few examples:

Frilled sharks (Chlamydoselachus anguineus) inhabit the deep sea where opportunities to feed are rare - so they need to be versatile enough to take advantage of anything that comes their way. They have trident-shaped needle-like teeth for catching slippery prey, but there is evidence that they use their white teeth and dark mouths to lure in small prey - so their teeth are widely spaced to create an unusual pattern. Credit: Citron [CC BY-SA 3.0]

Basking sharks (Cetorhinus maximus) are filter feeders, sifting microscopic organisms and food particles out of the water. Despite this diet making teeth useless, and their enormous size being a deterrent to predators, basking sharks still retail almost 1 500 vestigial teeth! Credit: Green Fire Productions [CC BY 2.0]

Cookiecutter sharks (Isistius brasiliensis) follow the "sawing" strategy of larger sharks, like white sharks, but in reverse - with their lower teeth being the ones used for cutting by locking together into a saw blade. This configuration allows these small sharks to bite plugs of blubber off of larger prey, like whales. Credit: JSUBiology [CC BY 2.0]

So, next time you see a shark - take a closer look at its features and see if you can figure out why it looks the way it does. This is the first step to being a shark scientist!