Nick Upton / Moorhen (Gallinula chloropus) foraging by up-ending among tree roots fringing a pond, near Bude, Cornwall, England, UK, April.

Nick Upton / Moorhen (Gallinula chloropus) foraging by up-ending among tree roots fringing a pond, near Bude, Cornwall, England, UK, April.

Mike Potts / Three Trumpeter swans (Cygnus buccinator) feeding at ice edge, two up-ending, resting during their long flight north to the breeding grounds of Alaska, Marsh Lake, Yukon, Canada, April

Roger Powell / Mallard (Anas platyrhynchos) drake up-ending while feeding, Northumberland, UK

Willem Kolvoort / Close up of Freshwater sponge (Spongilla lacustris) Green coloration due to presence of algae, Holland. Note the discharge tubes over the sponge ending in a discharge opening (centre top) where the wa...

Martin H Smith / Mallard duck decoys, Norfolk, UK

Tom Vezo / Male mallard (Anas platyrhynchos) 'up ending'. New York, USA

Mark Moffett / Kerengga Ant-like Jumper (Myrmarachne plataleoides) male in fighting posture showing elongated jaws ending in fangs which are usually sheathed, Sri Lanka

Tom Vezo / Male mallard duck dabbling, USA (Anas platyrhynchos)

John Cancalosi / Mute swan up-ending to feed {Cygnus olor} UK

Ross Hoddinott / Mute swan up-ending {Cygnus olor} Cornwall, UK