Tony Wu / Bowhead whale (Balaena mysticetus), group socialising in shallow water, aerial view. Part of larger group of more than 50 whales congregating, Sea of Okhotsk sub-population, Russia.

Nick Hawkins / North Atlantic right whale (Eubalaena glacialis) tail fluke, diving to feed in the Gulf of Saint Lawrence, Canada. Endangered species. July

David Gallan / Two Southern right whales (Eubalaena australis) playing in shallows, taken with drone, Tathra Beach, New South Wales, Australia, August.

Claudio Contreras / Grey whale (Eschrichtius robustus) breaching, San Ignacio Lagoon, El Vizcaino Biosphere Reserve, Baja California, Mexico, March

Claudio Contreras / Grey whale (Eschrichtius robustus) tail, San Ignacio Lagoon, El Vizcaino Biosphere Reserve, Baja California, Mexico, March

Claudio Contreras / Grey whale (Eschrichtius robustus) calf, San Ignacio Lagoon, El Vizcaino Biosphere Reserve, Baja California, Mexico, February

Mark Carwardine / Grey whale (Eschrichtius robustus) at water surface with mouth open showing baleen plates, San Ignacio Lagoon, Baja California, Mexico

Tony Wu / Grey whale (Eschrichtius robustus) calf at ocean surface, with its mother visible, Magdalena Bay, Baja California, Mexico.

Gabriel Rojo / Southern Right whale (Eubalaena australis) breaching, Peninsula Valdes, Chubut, Patagonia, Argentina.

Chris & Monique Fallows / Southern right whale (Eubalaena australis) breaching, False Bay, Cape Town, South Africa.

Chris & Monique Fallows / Southern right whale (Eubalaena australis) spyhopping, False Bay, Cape Town, South Africa.

Chris & Monique Fallows / Southern right whale (Eubalaena australis) close up feeding on plankton at surface, False Bay, Cape Town, South Africa; with barnacles on head