Doug Perrine / Nurse shark {Ginglymostoma cirratum}, Bahamas.

Doug Perrine / Nurse shark on coral reef {Ginglymostoma cirratum} Bahamas, Caribbean Sea (Non-ex).

Doug Perrine / Tawny nurse shark asleep under coral reef ledge {Nebrius ferrugineus} Burma Banks, Thailand, Andaman Sea (Non-ex).

Michele Westmorland / Scuba diver with Nurse shark (Ginglymostoma cirratum) in healthy marine life area 'Grand Canyon'. Grenada, West-Indies, Caribbean, May 2009. Model relased.

Alex Mustard / A large female Grey nurse /Sand Tiger / Ragged-tooth Shark (Carcharias taurus) Fish Rock, Southwest Rock, New South Wales, Australia. Pacific Ocean. In the final stages of pregancy, female gray nurse...

Alex Mustard / Grey nurse /Sand Tiger / Ragged-tooth Shark (Carcharias taurus) Fish Rock, Southwest Rock, New South Wales, Australia. Pacific Ocean. November

Alex Mustard / Grey nurse /Sand Tiger / Ragged-tooth Shark (Carcharias taurus) close up, Fish Rock, Southwest Rock, New South Wales, Australia. Pacific Ocean. November

Alex Mustard / Grey nurse /Sand Tiger / Ragged-tooth Shark (Carcharias taurus) Fish Rock, Southwest Rock, New South Wales, Australia. Pacific Ocean. November

Claudio Contreras / Nurse shark (Ginglymostoma cirratum) coming out of hole in rock, Cancun National Park, Caribbean Sea, Mexico, January

Claudio Contreras / Nurse shark (Ginglymostoma cirratum) Cancun National Park, Caribbean Sea, Mexico, January

Claudio Contreras / Nurse shark (Ginglymostoma cirratum)swimming over surface of seabed, Cancun National Park, Caribbean Sea, Mexico, July

Fred Bavendam / Grey Nurse Shark (Carcharias taurus) underwater portrait, New South Wales, Australia

Fred Bavendam / Grey Nurse Shark (Carcharias taurus) swimming over reef, New South Wales, Australia

Fred Bavendam / Grey Nurse Shark (Carcharias taurus), New South Wales, Australia

Michael Pitts / Nurse shark {Ginglymostoma cirratum} seeking shelter under the stern of a sunken fishing boat. British Virgin Islands.

Francis Abbott / Tawny nurse shark {Nebrius ferrugineus} swimming over coral reef, Indian Ocean

Francis Abbott / Tawny nurse shark {Nebrius ferrugineus} swimming over coral reef, Indian Ocean

Jeff Rotman / Nurse Shark (Ginglymostoma cirratum) feeding on bait with schooling sharks and reef fish, Bahamas, Caribbean Sea.

Norbert Wu / Grey Nurse Shark (Carcharias taurus) swimming near Papoose Wreck off North Carolina

Norbert Wu / Grey Nurse Shark (Carcharias taurus) pair and other small fish swimming through Papoose Wreck off North Carolina

Norbert Wu / Grey Nurse Shark (Carcharias taurus) swimming through Papoose Wreck with other small fish, off North Carolina

Norbert Wu / Grey Nurse Shark (Carcharias taurus) swimming through Papoose Wreck off North Carolina

Juergen Freund / Nurse shark (Ginglymostoma cirratum) Caribbean

Doug Perrine / Teeth of Sand tiger shark {Carcharias taurus} or Grey nurse shark {Odontaspis taurus}

Doug Perrine / Nurse shark on seabed {Ginglymostoma cirratum} Bahamas

Doug Perrine / Tawny nurse shark {Nebrius ferrugineus} amongst tropical fish, Andaman Sea, Thailand

Doug Perrine / Male Sand tiger shark showing claspers and lateral line {Carcharias taurus} Grey nurse

Mike Parry / Tawny Nurse Shark (Nebrius ferrugineus), Great Barrier Reef, Queensland, Australia

Mike Parry / Tawny Nurse Shark (Nebrius ferrugineus), Great Barrier Reef, Queensland, Australia

Norbert Wu / Grey Nurse Shark (Carcharias taurus) close-up of teeth and nose, Steinhart Aquarium, San Francisco, California

Norbert Wu / Grey Nurse Shark (Carcharias taurus) close-up of teeth and nose, Steinhart Aquarium, San Francisco, California

Fred Bavendam / Grey Nurse Shark (Carcharias taurus) swimming among schools of fish, New South Wales Australia

Fred Bavendam / Grey Nurse Shark (Carcharias taurus) underwater portrait, New South Wales Australia

Fred Bavendam / Grey Nurse Shark (Carcharias taurus) underwater portrait, New South Wales Australia

Juergen Freund / Nurse shark resting in cave. (Ginglymostoma cirratum) Pacific

Michael Pitts / Sharksucker on underside of Nurse Shark {Echeneis naucrates} Arabian Gulf

Juergen Freund / Tawny nurse shark eye, close-up {Nebrius ferrugineus} Indo Pacific

Jeff Rotman / Nurse shark {Ginglymostoma cirratum} rests on seabed, Bimini, Bahamas, Caribbean Sea.

Jeff Rotman / Nurse shark {Ginglymostoma cirratum} rests on seabed, Bimini, Bahamas, Caribbean Sea.

Jeff Rotman / Nurse shark {Ginglymostoma cirratum} rests on seabed, Bimini, Bahamas, Caribbean Sea.

Jeff Rotman / Nurse shark {Ginglymostoma cirratum} rests on seabed, Bahamas, Caribbean Sea.

Doug Perrine / Nurse shark profile {Ginglymostoma cirratum} Bahamas, Caribbean (Non-ex).

Doug Perrine / Nurse sharks {Ginglymostoma cirratum} Belize, Central America, Caribbean Sea (Non-ex).

Doug Perrine / Juvenile Sand tiger / Grey Nurse shark {Carcharias taurus} New South Wales, Australia (Non-ex).

Doug Perrine / Nurse shark {Ginglymostoma cirratum} Bahamas, Caribbean Sea (Non-ex).

Doug Perrine / Nurse shark resting under seafan {Ginglymostoma cirratum} Bahamas, Caribbean Sea (Non-ex).

Jeff Rotman / Nurse shark (Ginglymostoma cirratum) with symbiotic Remora cleaner fish, Bahamas

Jeff Rotman / Nurse shark rests on seabed {Ginglymostoma cirratum} Bimini, Caribbean.

Francis Abbott / Pregnant Tawny nurse shark, {Nebrius ferrugineus} Anderman Sea, Indian Ocean

Juergen Freund / Close up of Nurse shark eye {Ginglymostoma cirratum} Sula-sulawesi seas, Indo Pacific

Christian Ziegler / Short-tail Nurse Shark (Ginglymostoma cirratum) resting between mangrove roots, Bastimentos Marine National Park, Bocas del Toro, Panama

Ian Coleman / Illustration of Nurse shark (Ginglymostoma cirratum), Ginglymostomatidae.

Ian Coleman / Illustration of Sand tiger shark / Grey nurse shark / Spotted ragtooth shark (Carcharias taurus), Odontaspididae. Not to be confused with nurse shark. Endangered / threatened species.

Juergen Freund / Nurse shark feeding on bait fish (Ginglymostoma cirratum) BAHAMAS

Jeff Rotman / Nurse shark {Ginclymostoma cirratum} Remora {Echeneis naucrates} Bahamas