Remi Masson / Group of Wels catfish (Silurus glanis) gathered in the River Rhone, France, August.

Chris Mattison / Budgett's Frog (Lepidobatrachus laevis) mostly submerged in muddy water, with eyes visible above water, captive, occurs in South America.

Georgette Douwma / Cock's comb oyster (Lopha cristagalli) covered with encrusting sponge on artificial reef. Mabul, Malaysia.

Juergen Freund / Split level of large Purple crown jellyfish (Netrostoma setouchina) in shallows of mangroves. Mali Island, Macuata Province, Fiji, South Pacific.

Willem Kolvoort / White waterlily (Nymphaea alba) in Naardermeer bog lake, Holland. May.

Pascal Kobeh / Group of California sea lions (Zalophus californianus) in a kelp forest (Macrocystis pyrifera), California, USA. Pacific ocean.

Franco Banfi / Green anaconda (Eunectes murinus) underwater, flicking tongue, Formoso River, Bonito, Mato Grosso do Sul, Brazil

Graham Eaton / Compass Jellyfish, in murky water, Abersoch, Cardigan Bay, Wales, July

Pete Oxford / Butterfly peacock bass (Cichla ocellaris) in permanent freshwater pond, savannah, Rupununi, Guyana

Kevin Schafer / Split level view of Amazon River Dolphin / Boto (Inia geoffrensis) in flooded forest, Ariau River, tributary of Rio Negro, Amazonia, Brazil, July

Kevin Schafer / Two Amazon river dolphins / Botos (Inia geoffrensis) swimming underwater in flooded rainforest, one with beak open, Rio Negro, Amazonia, Brazil, July

Graham Eaton / Young Grey Seal (Halichoerus grypus) in murky water, Cardigan Bay, Wales, UK, July