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Do Crabs Bite?

We know they can pinch, but do crabs bite? When we think of these funny, sideways-walking creatures, the first image that pops to mind is definitely not a mouth full of teeth. Instead, we think of their strong, cleverly designed claws.

And for a good reason – their pincers are their first line of defense, unlike other animals that rely on their mouths and teeth for protection.

Like all other crustaceans, crabs have a hard, outer exoskeleton, jointed limbs (or legs), antennae, maxillae to help them funnel food into their mouths, and mandibles to chew it.

Biologically, this does leave one wondering about whether they even have teeth. In short, the answer is no. They do not have teeth in their mouths. However, they do have teeth-like structures on and in other parts of their bodies.

In this post, we’ll answer the question of whether crabs can bite while looking at their biological make-up in greater detail.

We’ll also investigate if they are inclined to “bite” other animals, especially when housed in captivity, and how much damage they can do in the process.

As a disclaimer, it’s best not to approach crabs in general unless you are accompanied by someone adept at dealing with these animals.

Do Crabs Bite?

Crabs do not bite in the way we understand biting to be an action of the mouth and teeth. Instead, they pinch with their powerful claws, which are often adorned with teeth-like structures that look like protrusions or ridges on their shells.

In fact, most crabs don’t have teeth in their mouths at all. Their teeth are located in their stomachs and are used to help digest their food.

A crab’s mouth is small to begin with, especially in comparison to its big, strong claws. Used almost strictly for eating, crabs grab onto food using their pincers before passing it into their mouths using their delicate maxillae.

From there, food is broken down by their mandibles and propelled into their stomachs when it is digested before exiting their systems.

When threatened, crabs will retaliate by pinching their enemy (animal or human) with their claws. This can feel dizzyingly similar to a bite because of the teeth-like protrusions often found lining their pincers and the sheer force of pressure they’re able to exert.

Depending on their size, a pinch by a crab can draw blood and even fracture bones. Fortunately, they are shy and afraid of humans, so they are unlikely to attack you unless provoked.

Will Crabs Bite Fish Living In Their Aquarium?

Crabs are very unlikely to bite, pinch, or otherwise harm live fish living in an aquarium, provided the fish are not substantially smaller than they are.

However, they may prey or feed on dying or deceased fish, as they are generally scavenger animals. Most often, the types of crabs found in aquariums feed on algae or other microorganisms living in the tank, but that being said, feeding habits vary depending on the species.

Hobbyists and aquarists have been keeping crabs in their tanks for years as part of a specialized “cleaning crew” to keep things neat and tidy.

The common types of crabs we find in aquariums are usually porcelain crabs, anemone crabs, hermit crabs, Sally Lightfoot crabs, and Mithrax crabs. While they tend to feed on algae, they will stray from their usual diet in favor of other foods if they are hungry and out of options.

While porcelain, anemone, and hermit crabs present no threat to living fish, Sally Lightfoot and Mithrax crabs may go after live fish that are much smaller than them if they are in need of food. It’s difficult for crabs to catch fish, which is why they tend to strike while fish are resting.

Furthermore, they do not bite them, per se, but instead, subdue them using their powerful claws. Once no longer struggling, crabs pass their crushed prey into their mouths to consume.

Does A Crab Bite Hurt?

While crabs will not bite humans, they can pinch them, which can be exceptionally painful depending on the size of the creature in question.

Crabs are known for the force behind their claws, which is significant in correlation to their body size, and species-dependent can be even more powerful than the bite of some animals.

With some crab species, a pinch can feel like a bite because of the teeth-like structures often found lining their pincers.

The pain caused by a crab pinch depends on its size and species. A small, run-of-the-mill beach crab may only exert enough force to leave you with a bit of a sting, while bigger species, like the Dungeness crab, can pinch hard enough to draw blood and even fracture a bone. The more specific problem with crabs is that once they have a hold, they’re not inclined to let go all that easily.

If a crab pinches you, you need to clean the wound with a disinfectant solution and bandage it if there is any lesion to the skin. It’s best not to mess with crabs, of course, but if they do manage to get hold of you, you’re unlikely to suffer anything more than a bit of discomfort. Irrespective of the fact that crabs can’t bite humans, they can do some damage with their strong, scary claws.


Crabs have all the potential to be quite fearsome, especially with their big, strategically designed pincers. Fortunately, they’re rather retiring creatures and won’t attack humans for no reason. Conversely, they reserve their pent-up frustration for grinding up prey or fighting with their fellow crabs. And while they can’t bite you, they can cause pain by pinching, and they can be destructive in aquariums, so it’s best to keep a safe distance from them and do your research before adopting them as pets.