Spatial learning and memory retention in the grey bamboo shark (Chiloscyllium griseum).

Like other vertebrates, fish can learn to solve a wide variety of tasks; however, many of their cognitive abilities, particularly in cartilaginous fishes, still remain unknown. This study investigated memory retention capabilities of spatial learning tasks in the grey bamboo shark (Chiloscyllium griseum, n=8) after behavioural training in a two-choice experiment (T-maze). Sharks learned to obtain food at a goal location, either by performing a specific turn response or by using a variety of external landmarks for guidance. Following successful training, sharks were subjected to several training breaks ranging from one to six weeks, after which they were tested again for memory retention capabilities. Sharks successfully mastered the spatial tasks after 5-21 sessions and retained this knowledge in the absence of reinforcement for a period of up to six weeks. This is the first study to show that sharks, like stingrays and other vertebrates, can solve spatial tasks and retain spatial knowledge for an extended period of time, possibly aiding them in activities such as food retrieval, predator avoidance, mate choice and habitat selection.