Octopus hunting a crab.

The suckers on an octopus’s arms not only help it to capture a crab but also allow it to taste its prey. Credit: Peter Kilian

Neuroscience

How octopuses taste with their arms — all eight of them

Some of the cells on a cephalopod’s suckers respond to substances produced by ocean creatures.

The arms of an octopus are lined with hundreds of suckers, each of which can act as a taste bud. Now, researchers have found that cells on the suckers’ surfaces allow the California two-spot octopus (Octopus bimaculoides) to taste its food.

Nicholas Bellono at Harvard University in Cambridge, Massachusetts, and his colleagues analysed how octopuses behaved when their suckers touched an object. The octopuses wrapped crabs — a prey item — in their arms after probing them with the suckers, but they ignored inanimate objects. This confirmed that the animals use their suckers to detect food.

Previous research has shown that the suckers are dotted with sensory cells. Bellono’s team found that structures called chemotactile receptors on the surface of some of these cells respond to specific molecules, including terpenoids, which many marine invertebrates produce as a defence mechanism. After binding to these chemicals, the receptors generate an electrical signal that passes chemical and tactile information to the octopus’ nervous system.

The findings could explain how octopuses explore the sea-floor by tasting objects with their arms, the researchers say.