Sea Soul series, part 2

Dolphin Secrets

Bottlenose dolphins call each other with signature whistles, rest one half of the brain at a time, and pass a hunting tool from mother to daughter.

Bottlenose dolphin swimming up toward the sunlight in deep blue water at Dolphin Reef, Eilat, Israel — Photo: טל שמע, CC BY-SA 4.0, Wikimedia Commons

Part 2 of Sea Soul Secrets is about the bottlenose dolphin, the animal behind Sea Smile.

Dolphins have something close to names. The Sarasota Dolphin Research Program in Florida, which began in 1970 and is the longest-running study in the world of a wild population of dolphins and whales, found that each dolphin mostly uses one unique signature whistle. These whistles stay stable over a lifetime, especially for females. To reach a particular dolphin, another can copy its whistle, much like calling someone by name. The programme's whistle database holds nearly 1,000 recording sessions of 324 individual dolphins.

They sleep with half a brain. Dolphins rest one half of the brain at a time. Researchers think this lets them keep coming up to breathe. In a study led by Brian Branstetter of the National Marine Mammal Foundation, dolphins stayed alert for at least 15 days in a row and used echolocation (finding things by sound) with near-perfect accuracy. The female in the study kept up her tasks for the full 15 days.

Some use tools. In Shark Bay, Western Australia, certain dolphins break off basket-shaped sponges and carry them over their beaks to search rough seabed for fish without getting hurt. The skill passes mainly from mothers: 91 per cent of daughters took it up, compared with 25 per cent of sons.

They work as a team. NOAA Fisheries describes dolphins herding fish into tight groups and taking turns to charge through them. Calves stay close to their mothers for a long time and feed on milk for about 20 months.

Meet Sea Smile in the Sea Soul collection.