LYNN M. STONE / Bullfrog (Rana catesbeiana) with head sticking out above water in pond, Deep River, Connecticut, USA, July

Tony Heald / African bullfrogs {Pyxicephalus adspersus} group of males in water, Etosha NP, Namibia, January

Tony Heald / African bullfrog {Pyxicephalus adspersus} vanquished male leaps away from fight, Etosha NP, Namibia, January

Jabruson / African bullfrog {Pyxicephalus flavigula} Tsavo East NP, Kenya

Jabruson / Bullfrog eating mouse {Pyxicepalus flavigula} Tsavo East NP, Kenya

Rolf Nussbaumer / Close-up of a Bullfrog eye {Rana catesbeiana} with head camouflaged in duckweed, Welder Wildlife Refuge, Sinton, Texas, USA.

Doug Wechsler / Bullfrog male in garden pond {Rana catesbeiana} Pennsylvania, USA.

Doug Wechsler / Bullfrog female by garden pond {Rana catesbeiana} Pennsylvania, USA

Mark Payne-Gill / African bullfrog / Giant bullfrog /Pixie frog (Pyxicephalus adspersus) male digs canal to rescue tadpoles from drying puddle, South-Africa. Second prize winner in this Wildlife Photographer of the Ye...

Jabruson / African bullfrog {Pyxicephalus flavigula} eating mouse. Tsavo East NP, Kenya

Michael D. Kern / African Bull Frog / Pixie Frog (Pyxicephalus adsperus) captive from Southern Africa

Pete Oxford / Smokey Jungle Frog (Leptodactylus pentadactylus), Yasuni National Park, Amazon, Ecuador

Chien Lee / Malaysian Bullfrog (Kaloula pulchra), Krabi, Thailand

Chien Lee / Malaysian Bullfrog (Kaloula pulchra), Krabi, Thailand

Bert Willaert / Crowned Bullfrog (Hoplobatrachus occipitalis) portrait. Bobiri Butterfly Sanctuary, Ghana.

LYNN M. STONE / Bullfrog (Rana catesbeiana) on edge of pond, Connecticut, USA

LYNN M. STONE / Bullfrog (Rana catesbeiana) on edge of pond, Connecticut, USA

Ian Lockwood / Indian bullfrog (Rana tigerina) India

Michael D. Kern / Giant pixie frog / African bullfrog (Pyxicephalus adspersus) captive, from Africa

Murray Cooper / Smokey Jungle Frog (Leptodactylus pentadactylus) camouflaged in leaf litter, Amazon, Ecuador

Doug Wechsler / Bullfrog (Rana catesbeiana) male, in man-made pond, Farimount Park, Wissahickon Creek, Philadelphia, Pennsylvania, USA

Doug Wechsler / Bullfrog (Rana catesbeiana) male, in man-made pond, Farimount Park, Wissahickon Creek, Philadelphia, Pennsylvania, USA

Gerrit Vyn / Bullfrog (Rana catesbeiana) partially submerged in a pond. August. Tompkins County, New York

James Christensen / Smokey Jungle Frog (Leptodactylus pentadactylus) with injured jaw, Colon, Panama

Thomas Marent / African Bullfrog (Pyxicephalus adspersus) in mud, introduced species, Ankarana Special Reserve, Madagascar

Thomas Marent / African Bullfrog (Pyxicephalus adspersus) in mud, introduced species, Ankarana Special Reserve, Madagascar

Thomas Marent / American Bullfrog (Rana catesbeiana), Reserva Natural Laguna de Sonso, Colombia

Thomas Marent / American Bullfrog (Rana catesbeiana) portrait, Reserva Natural Laguna de Sonso, Colombia

Thomas Marent / American Bullfrog (Rana catesbeiana) portrait, Reserva Natural Laguna de Sonso, Colombia

Thomas Marent / American Bullfrog (Rana catesbeiana) portrait, Reserva Natural Laguna de Sonso, Colombia

Thomas Marent / American Bullfrog (Rana catesbeiana), Reserva Natural Laguna de Sonso, Colombia

Thomas Marent / American Bullfrog (Rana catesbeiana), Reserva Natural Laguna de Sonso, Colombia

Michael & Patricia Fogden / American Bullfrog (Rana catesbeiana) in leaf litter showing tympanum, North America

Dave Bevan / Bullfrog (Rana catesbiana) surfacing in pond, Kent, UK, June

Tony Heald / African bullfrog {Pyxicephalus adspersus} male in water, Etosha NP, Namibia, January

Tony Heald / African bullfrog {Pyxicephalus adspersus} Etosha NP, Namibia, January

Tony Heald / African bullfrog {Pyxicephalus adspersus} males fighting, Etosha NP, Namibia, January

Tony Heald / African bullfrog {Pyxicephalus adspersus} swimming, Etosha NP, Namibia, January

Tony Phelps / African bullfrog {Pyxicephalus adspersus} Pretoria, South Africa

Tony Phelps / African bullfrog {Pyxicephalus adspersus} Pretoria, South Africa

Tony Phelps / African bull frog {Pyxicephalus adspersus} in aestivation, Gauteng, South Africa

Jabruson / African bullfrog {Pyxicephalus flavigula} emerging from burrow, Tsavo East NP, Kenya

Nature Production / Bullfrog {Rana catesbeiana} tadpole (110mm in length) sequence 6/8

Nature Production / Bullfrog {Rana catesbeiana} tadpole (52mm in length) sequence 5/8

Nature Production / Bullfrog {Rana catesbeiana} tadpole (34mm in length) sequence 4/8

Nature Production / Bullfrog {Rana catesbeiana} tadpole (23mm in length) sequence 3/8

Nature Production / Bullfrog {Rana catesbeiana} tadpole (8mm in length) sequence 2/8

Nature Production / Bullfrog {Rana catesbeiana} tadpole (8mm in length) sequence 1/8

Nature Production / Bullfrog {Rana catesbeiana} tadpole (80mm in length) sequence 8/8

Nature Production / African Bullfrog {Pyxicephalus adspersus} captive

Nature Production / Bullfrog {Rana catesbeiana} sheet of eggs on water

Nature Production / Bullfrog {Rana catesbeiana} tadpole (91mm in length, with hind legs developing) sequence 7/8

Barry Mansell / African bullfrog portrait (Pyxicephalus adspersus) Africa, captive

Michael & Patricia Fogden / Smokey Jungle Frog (Leptodactylus pentadactylus) predating Masked Puddle Frog (Smilisca phaeota), Costa Rica

Jabruson / African bullfrog {Pyxicephalus flavigula} emerging from burrow after rain, Tsavo East NP, Kenya

Pete Oxford / Indian bullfrog {Rana / Hopobatrachus tigerina} on lily pad, Perinet, E Madagascar

Jabruson / African bullfrog {Pyxicephalus flavigula} feeding on mouse, Tsavo East NP, Kenya

Doug Wechsler / Bullfrog female {Rana catesbeiana} Lafayette Hill, Pennsylvania, USA

Jabruson / Bullfrog {Pyxicephalus flavigula} emerging from summer sleep, Tsavo NP, Kenya, East Africa

Jabruson / Bullfrog emerging from mud and summer aestivation {Pyxicepalus flavigula} Tsavo East NP, Kenya

Doug Wechsler / Bullfrog tadpole, 1st autumn {Rana catesbeiana} Pennsylvania, USA

Doug Wechsler / Bullfrog tadpole {Rana catesbeiana} Pennsylvania, USA

Rolf Nussbaumer / Bullfrog {Rana catesbeiana} camouflaged in duckweed with eyes visible, Welder Wildlife Refuge, Sinton, Texas, USA.

Doug Wechsler / Bullfrog male in garden pond {Rana catesbeiana} Pennsylvania, USA

Robert Valentic / Asian painted frog / Common bullfrog {Kaloula pulchra} Singapore

Larry Michael / Bullfrog in water {Rana catesbeiana} Wisconsin USA.

Doug Wechsler / Bullfrog camouflaged in pond {Rana catesbeiana} Delaware, USA.

Dave Bevan / Bullfrog tadpole {Rana catesbeiana} and Stickleback fish amongst aquatic plant, Wales, UK. Captive.

Gerry Ellis / Tremolo Sand Frog (Tomopterna cryptotis) among leaves on rainforest floor, Matetsi safari area, Zimbabwe

Michael & Patricia Fogden / Northern Banjo Frog (Limnodynastes terraereginae) portrait, Queensland, Australia

Michael & Patricia Fogden / Northern Banjo Frog (Limnodynastes terraereginae) portrait, Queensland, Australia

Michael & Patricia Fogden / Smokey Jungle Frog (Leptodactylus pentadactylus) tadpoles eating eggs of Tarraco Treefrog (Smilisca phaeota) in rainforest, Costa Rica

Jim Brandenburg / American Bullfrog (Rana catesbeiana) at edge of lake, Minnesota

ZSSD / American Bullfrog (Rana catesbeiana) albino in water, North America

Barry Mansell / Bullfrog {Rana catesbeiana} Florida, USA

Jabruson / Bullfrog {Pyxicephalus flavigula} Tasvo East NP, Kenya

Onne van der Wal / A family cruising on a Holby motorboat.

Jabruson / Bullfrog {Pyxicephalus flagrigula} feeding on mouse. Eyeballs receded into top of head to help push food through mouth.

Barry Mansell / Bull frog {Rana catesbeiana} C Florida USA