Academic Review 2024

17 ACADEMIC REVIEW 2024

“ Dolphins get bored quickly listening to signature whistles from dolphins they don’t know. ”

was the beginning of their friendship. The orca was transferred to France and two years later, Jonsson visited it at its aquarium. Their bond was so strong that immediately after the killer whale finished its act, it swam straight to Jonsson, shaking its head, clearly showing some sort of affection due to the recognition (Garrett, 1997). Jonsson also mentions another orca called Keiko, famed for his role in the film Free Willy . He was captured in 1979 at two years old and released back to the wild in 2002, 23 years later (Simon, Hanson, Murrey, Tougaard, & Ugarte, 2009). Jonsson (1997) asks, ‘Why shouldn’t Keiko remember how to hunt, or recognize his fellows, after 20 years?’ He believes orcas, such as the one he cared for, have the ability to show recognition even after 20 years, proving a very strong long-term memory.

T. truncatus have ‘the longest social memory ever recorded for a non-human species’ (Manier, 2013). Their ability to recognise each other’s signature whistles is possibly greater than human ability to recognise faces, as faces change over time while signature whistles stay identical throughout a dolphin’s life. A study to show the social memory of T. truncatus was completed by Jason Bruck. He used 53 dolphins in captivity for this investigation (Manier, 2013). Bruck made these dolphins listen to different recordings of these signature whistles, some of which were random while others were the whistles of dolphins they knew. He found that: ‘Dolphins get bored quickly listening to signature whistles from dolphins they don’t know’ (Manier, 2013). In contrast instantaneous feedback was shown when the dolphins were played the recordings of other dolphins they once knew. This was repeated and was controlled to make sure there was no third variable to the results. One of his remarkable findings was that the signature whistle was recognised even when the dolphins had been apart for 20 years and six months. (Manier, 2013). It is still unclear why bottlenose dolphins have such an incredible long-term memory but it adds another branch to their social connections therefore aiding them to respond to any threats in the wild. The colossal brain size of O. orca potentially links to a memory of considerable magnitude. Elias Jonsson (1997) describes his experience of when a killer whale was so nauseous after travelling for six hours, that it didn’t even have the ability to hold itself the right way up in the water, so Jonsson had to hold it up, thankfully preventing it from drowning. This