The coconut crab (Birgus latro)

The coconut crab has a well-developed sense of smell, which it uses to locate its food.[25] The process of smelling works very differently depending on whether the smelled molecules are hydrophilic molecules in water or hydrophobic molecules in air. Crabs that live in water have specialized organs called aesthetascs on their antennae to determine both the denseness and the direction of a scent. Coconut crabs live on the land, so the aesthetascs on their antennae are shorter and blunter than those of other crabs and are more similar to those of insects.[25]

While insects and the coconut crab originate from different paths, the same need to track smells in the air led to the development of remarkably similar organs. Coconut crabs flick their antennae as insects do to enhance their reception. Their sense of smell can detect interesting odors over large distances. The smells of rotting meat, bananas, and coconuts, all potential food sources, catch their attention especially.[26] The olfactory system in the coconut crab's brain is well-developed compared to other areas of the brain.[27]

Lifecycle