Scientist lying on 10ft long bowsprit of research yacht, Silurian, to photo-identify common dolphins. Hebrides, Scotland.

Scientist positioned on bowsprit of research yacht, Silurian, to photo-identify common dolphins. Hebrides, Scotland.

Two Common dolphins porpoising (Delphinus delphis) Barra Head, Scotland, UK

Scientist on bow of the research yacht, Silurian, to photo-identify common dolphins. Hebrides, Scotland.

Common dolphin (Delphinus delphis) surfacing at speed, Gibraltar

Common dolphin (Delphinus delphis) - close up dolphin surfing at speed, with eye visible through a film of water. Hebrides, Scotland.

Pod of Common dolphins surfacing (Delphinus delphis) Azores, Atlantic Ocean

Pod of Common dolphins surfacing (Delphinus delphis) off Angola, West Africa

Common dolphins (Delphinus delphis) surfacing at speed in very calm waters. Eye, beak, flipper and dorsal fin visible above the surface. Hebrides, West coast of Scotland.

Common dolphin with baby surfacing (Delphinus delphis) Azores, Atlantic Ocean

Two Common dolphins surfacing (Delphinus delphis) Azores, Atlantic Ocean

Adult Common Dolphins (Delphinus delphis) leaping in the upper Gulf of California (Sea of Cortez), Mexico.

Common dolphin (Delphinus delphis). Hebrides, Scotland.