Doug Gimesy / Long-nosed potoroo (Potorous tridactylus) portrait showing sharp curved claws on front feet for foraging, Victoria, Australia. Controlled conditions.

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.

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.

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

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.

Cyril Ruoso / Adult male Drill (Mandrillus leucophaeus) yawning, mouth wide open showing canine teeth, Pandrillus Sanctuary, Nigeria. Non-ex

Todd Mintz / Great horned owlet (Bubo virginianus) talons Regina, Saskatchewan, Canada. June 2013.

Stephen Dalton / Close-up of holly leaf (Ilex aquifolium).

Olga Kamenskaya / Clear panes of ice on Lake Baikal, Siberia, Russia, March.

Chris & Monique Fallows / Great white shark (Carcharodon carcharias) feeding on Brydes whale carcass (Balaenoptera brydei), Seal Island, False Bay South Africa.

Alex Hyde / Common Wasp (Vespula vulgaris) close up of sting, UK

Paul Hobson / Azure Damselfly (Coenagrion puella) male grasping stem with eyes and head in sharp focus. Sheffield, UK, May. 'Animal Portraits' category, British Wildlife Photography Awards (BWPA) competition 2012.

MYN / Marko Masterl / Hepatica (Hepatica nobilis) in flower, Slovenia, Europe, March. meetyourneighbours.net project

Alex Mustard / An adult California sealion (Zalophus californianus) makes a sharp turn at high speed. Los Islotes, La Paz, Baja California, Mexico. Sea of Cortez, East Pacific Ocean.

Wild Wonders of Europe / Widstrand / Hepatica / Blue anemone (Hepatica nobilis) flowers, Sabysjon, Uppland, Sweden, April 2009

Jack Dykinga / Dramatic rosette of spiked leaves of a Yucca plant, Tucson, Arizona, USA

Wild Wonders of Europe / Schandy / Early morning light on sharp peaks, seen from Elbrus, Caucasus, Russia, June 2008

Tony Heald / RF- Black rhinoceros (Diceros bicornis) looking threatening, Etosha National Park, Namibia, June. Endangered species. (This image may be licensed either as rights managed or royalty free.)

David Welling / Sharp shinned hawk {Accipiter striatus} juvenile bathing, Texas, USA

Jurgen Freund / Close up of Giant Stinging Tree hairs on the leaves (Urticastrum gigas or Dendrocnide excelsa). Contact with the leaves or twigs causes the hollow silica-tipped hairs to penetrate the skin. Australia

Igor Shpilenok / Kluchevskoy Volcano, the highest volcano in Eurasia, flanked by volcanos Plosky (flat) Tolbachik and Ostry (sharp) Tolbachik. Kluchevskoy Nature Reserve, Central Kamchatka. .

Aflo / ic-17711 American bald eagle close-up profile of beak and eye {Haliaeetus leucocephalus}

Pete Oxford / Man holding Piranha to showing sharp teeth & jaws {Serrasalmidae family} Ecuador South America, Amazon

Ingo Arndt / Alpine Marmot (Marmota marmota) showing sharp teeth while calling, Hohe Tauern National Park, Austria

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

Alan Murphy / Sharp-shinned Hawk (Accipiter striatus) flying, Texas

Alan Murphy / Sharp-shinned Hawk (Accipiter striatus) attacking bird in flight, Texas

Alan Murphy / Sharp-shinned Hawk (Accipiter striatus) flying, Texas

Alan Murphy / Sharp-shinned Hawk (Accipiter striatus) flying, Texas

Steve Gettle / Sharp-tailed Grouse (Tympanuchus phasianellus) male displaying at lek, Seney National Wildlife Refuge, Michigan

Konrad Wothe / Blacktail Piranha (Pygocentrus piraya) on hook showing sharp teeth, Pantanal, Brazil

Tony Wu / Great barracuda (Sphyraena barracuda) stalking prey, close up of mouth with sharp teeth. Bangka, North Sulawesi, Indonesia.

Nigel Cattlin / Sharp eyespot (Ceratobasidium cereale) eye-shaped pale lesions of a fungal disease on wheat stem base

Enrique Lopez-Tapia / Sharp mountain peaks of the Zanskar range glowing at sunset, full moon overhead. Ladakh, India. September 2011.

Fred Olivier / Deep water sponge (with very sharp glass spicules) captured during a deep benthic trawl, Southern Ocean, February 2015.

Linda Pitkin / Clustered dock (Rumex conglomeratus). Hampton Court, Richmond Upon Thames, England, UK. July.

Tony Wu / Juvenile Chinese pond turtle (Mauremys reevesii), measuring 10cm, climbing in enclosure. They have sharp claws and strong muscles, and are excellent climbers. Rescued from a road, hand-reared now, Jap...

Nick Hawkins / Aerial view of a dead North Atlantic right whale (Eubalaena glacialis) on beach in Cape Breton, Canada. The whale, known as 'Punctuation' to researchers, was a large female who scientists have...

Nick Hawkins / Aerial view of a dead North Atlantic right whale (Eubalaena glacialis) on beach in Cape Breton, Canada. The whale, known as 'Punctuation' to researchers, was a large female who scientists have...

Nick Hawkins / Researchers perform a necropsy on dead North Atlantic right whale (Eubalaena glacialis) on beach in Cape Breton, Canada. The whale, known as 'Punctuation' to researchers, was a large female wh...

Nick Hawkins / A dead North Atlantic right whale (Eubalaena glacialis) on beach in Cape Breton, Canada. The whale, known as 'Punctuation' to researchers, was a large female who scientists have been tracking...