Alex Mustard / Tiger cardinalfish (Cheilodipterus macrodon) male mouth brooding a clutch of eggs behind his sharp teeth. Gubal Island, Egypt. Strait Of Gubal, Red Sea.

Ashley Cooper / Needle ice on Holly leaves (Ilex europaeus) in a woodland in Ambleside Cumbria UK. December 2008

Tony Wu / Indo-Pacific sailfish (Istiophorus platypterus) in feeding frenzy, with the remains of a previously large school of sardines (Sardina sp) in background. Isla Mujeres, Cancun, Mexico.

Alan Murphy/ BIA / Sharp-tailed Grouse (Tympanuchus phasianellus) males fighting at lek in snow, Minnesota

Alan Murphy/ BIA / Sharp-tailed Grouse (Tympanuchus phasianellus) males fighting at lek in snow, Minnesota

Alan Murphy/ BIA / Sharp-tailed Grouse (Tympanuchus phasianellus) male displaying at lek in snow, Minnesota

Nick Saunders/ BIA / Sharp-shinned Hawk (Accipiter striatus) juvenile, Saskatchewan, Canada

Richard Robinson / Shortfin mako shark (Isurus oxyrinchus) head on just below surface, another in background, off the West Coast of Auckland, New Zealand, February

Richard Robinson / Shortfin mako shark (Isurus oxyrinchus) profile portrait, just below surface, off the West Coast of Auckland, New Zealand, February

Chris & Monique Fallows / Mako shark (Isurus oxyrinchus) with sunrays, Cape Point, South Africa, March.

Chris & Monique Fallows / Mako shark (Isurus oxyrinchus) near surface, Cape Point, South Africa, March 2015

Franco Banfi / Humboldt squid (Dosidicus gigas) at night off Loreto, Sea of Cortez, Baja California, Mexico, East Pacific Ocean.