The Nose

Crabs also don’t have noses, at least not like we’d understand.

Crabs are however capable of sensing tiny amounts of chemicals in the water, so we can think of this like smelling.

They have minute structures on the outside of their shells called sensilla which receive chemical information from their environment.

We call this process chemoreception.

The sensilla are most concentrated on the first antennae, the last segment of the walking legs and the mouth bits. By having these receptors on their legs crabs are able to detect tiny bits of food under the surface of the sediment.

Land crabs smell in a similar way to insects, anatomically, behaviourally and physiologically, but much less effectively.

They are especially sensitive to food organisms in the water and sex pheremones. In fact so sensitive that they can detect sex pheremones at one part in a quadrillion.

Saucy things.

Pictured is the Porcelain Crab Neopetrolisthes maculatus