Researchers have found that cuttlefish have number sense, including the ability to discern the difference of two quantities. The cuttlefish also showed variation in their responses depending on factors such as their current appetite. The findings are in a paper just published in the journal Proceedings of the Royal Society B.
Cuttlefish are cephalopods, the class that also includes squids, octopuses, and nautiluses. They are masters of camouflage, able to change their body’s colors and patterns to perfectly match their environment. Cuttlefish are also known for having the largest brain of any invertebrate, leading researchers to study their intelligence and problem-solving abilities.
Researchers from the National Tsing Hua University in Taiwan studied a group of captive untrained cuttlefish. In a series of trials, the cuttlefish were offered the choice between two food options. In the first type of trial, the cuttlefish were offered a choice between two different quantities of shrimp, a favorite food of cuttlefish. The cuttlefish always chose the option with more shrimp, showing that the animals have at least basic number sense. In another trial, the cuttlefish were offered a choice of either living or dead shrimp. The cuttlefish always chose live shrimp and even preferred one live shrimp to two dead ones.
The researchers wanted to see if appetite made a difference in the choices of the cuttlefish. They found that when a cuttlefish was hungry, it would choose a large shrimp instead of two smaller ones. When a cuttlefish wasn’t hungry, however, they would consistently choose the two smaller shrimp. This shows that the cuttlefish were adapting their foraging choices based on their appetite.
Cuttlefish are already known for their large brains and intelligence. This new research shows that they also have number sense and are able to tell the difference between two different quantities. The cuttlefish also had the ability to adapt their decisions based on factors such as their level of hunger. These findings add to a growing amount of evidence on cuttlefish intelligence.
Tsang-I Yang et al. Number sense and state-dependent valuation in cuttlefish. Proceedings of the Royal Society B (2016).