Nick Hawkins / Blue shark (Prionace glauca) with a pair of pilot fish (Naucrates ductor) off Halifax, Nova Scotia, Canada. July.

Nick Hawkins / Blue shark (Prionace glauca) off Halifax, Nova Scotia, Canada. July.

Nick Hawkins / Overhead view of a blue shark (Prionace glauca) off Halifax, Nova Scotia, Canada. July.

Pascal Kobeh / Blue shark (Prionace glauca) Azores, Atlantic Ocean.

Shane Gross / Lemon shark pup (Negaprion brevirostris) in mangrove forest which acts as a nursery for juveniles of this species. Eleuthera, Bahamas.

Shane Gross / Lemon shark pup (Negaprion brevirostris) in mangrove forest which acts as a nursery for juveniles of this species. Eleuthera, Bahamas.

Shane Gross / Lemon shark pup (Negaprion brevirostris) in mangrove forest which acts as a nursery for juveniles of this species. Eleuthera, Bahamas.

Jordi Chias / Split level view of Blue shark (Prionace glauca) at surface at sunset, Azores Islands, Portugal, Atlantic Ocean

Franco Banfi / Lemon shark (Negaprion brevirostris) Northern Bahamas, Caribbean Sea, Atlantic Ocean

Richard Robinson / Blue shark (Prionace glauca) just below surface, Hauraki Gulf, Auckland, New Zealand, June.

Richard Robinson / Blue shark (Prionace glauca) viewed from below, off the coast of Hawke's Bay, New Zealand, February.

Richard Robinson / Blue shark (Prionace glauca) worked from below with rays of sun, off the coast of Hawke's Bay, New Zealand, February.