Mark Carwardine / Pacific white-sided dolphin / Lag (Lagenorhynchus obliquidens) swimming fast, showing dorsal fin, Johnstone Strait, Vancouver Island, British Columbia, western Canada

Steven Kazlowski / Killer whale (Orcinus orca) large pod with one male approaching, in Kenai Fjords National Park, Chiswell Islands National Marine Sanctuary, South Central Alaska, USA

Alex Mustard / Basking shark (Cetorhinus maximus) rear view of shark feeding at the surface on plankton, Cairns Of Coll, Isle of Coll, Inner Hebrides, Scotland, UK, North East Atlantic Ocean, June

Cheryl-Samantha Owen / Blacktip reefs sharks (Carcharhinus melanopterus) dorsal fins visible at sea surface at dusk, Aldabra Atoll, Seychelles, Indian Ocean

Alex Mustard / 2020VISION / Dorsal fin of a Basking shark (Cetorhinus maximus) at the surface, Cairns of Coll, Inner Hebrides, Scotland. UK, June.

MYN / Piotr Naskrecki / Red spotted newt (Notophthalmus viridescens) juvenile / eft, dorsal view, Concord, Massachusetts, USA, June. meetyourneighbours.net project

Jeff Rotman / Poisonous dorsal spines of Tassled scorpionfish (Scorpaenopsis oxycephalus) Red Sea, Egypt

Kathryn Jeffs / Southern Type B Killer whale (Orcinus orca) hunting Weddell seal (Leptonychotes weddelli), Antarctica. Taken on location for BBC Frozen Planet series, January

David Maitland / Close-up view of the upward-looking giant dorsal compound eyes of the St Marks fly (Bibio marci) used to detect female flies flying above. Like many insects the eyes are "hairy". Feltwell, Norfolk, UK...

David Maitland / Close-up view of the upward-looking giant dorsal compound eyes of the St Marks fly (Bibio marci) used to detect female flies flying above. Like many insects the eyes are "hairy". Feltwell, Norfolk, UK...

Nuno Sa / Great Blue Shark (Prionace glauca), dorsal view against dark water. Over 20 million Blue Sharks are fished annually, as bycatch and due to the high value of their fins. Azores, North Atlantic, Septemb...

Martin Camm / Carwardine / Illustration of Striped dolphin (Stenella coeruleoalba), Delphinidae (Wildlife Art Company).