Dolphin

A self-aware marine mammal

Bottlenose dolphins are among a small handful of non-human animals that have passed the mirror self-recognition test — a marker often used as a proxy for self-awareness. Marked with paint and given a mirror, they investigate the marked area on their own bodies, demonstrating that they understand the reflection represents themselves. The exclusive club of mirror-passers includes humans, great apes, elephants, magpies, and a few other species.

Signature whistles

Each dolphin develops its own unique “signature whistle” within the first months of life — a vocal label that functions like a name. Dolphins use signature whistles to identify themselves and call to specific individuals. Mothers call to their offspring with the offspring’s whistle; pod members exchange whistles when meeting up. They also remember and recognize each other’s whistles after decades of separation, the longest-known social memory in any non-human.

Echolocation

Dolphins emit rapid clicks and listen for echoes through specialized fat-filled jaws, building a 3D acoustic image of their environment. The system can detect a metal object the size of a marble at over 100 m, and discriminate fine details like the species of fish, whether a fish is wounded, and even (with training) tell apart objects of slightly different size.

Cooperative hunters

Bottlenose dolphins demonstrate remarkable cooperative hunting behaviors that vary by population — clear evidence of cultural transmission:

• Mud-ring feeding (Florida) — one dolphin sweeps mud from the bottom in a circle, trapping fish that leap into other dolphins’ mouths.
• Strand feeding (South Carolina, Argentina) — dolphins drive fish onto mud banks and follow them out of water briefly.
• Sponge tools (Shark Bay, Australia) — females wear sea sponges on their snouts as protection while foraging on the rough bottom; the technique is taught by mothers to daughters.

Two species, three subspecies

What’s commonly called “the bottlenose dolphin” is now recognized as at least two distinct species (Tursiops truncatus and Tursiops aduncus) with complex regional populations that are still being sorted out. The classic Flipper-style dolphin of marine parks is T. truncatus.