Georgette Douwma / Green turtle (Chelonia mydas) with two large remoras (Echeneis naucrates) attached to its carapace, at rest on artificial reef. Mabul, Malaysia.

Alex Mustard / Lemon shark (Negaprion brevirostris) accompanied by Remoras (Echeneis naucrates) at night. Little Bahama Bank, Bahamas. Tropical West Atlantic Ocean.

Doug Perrine / Female Bull sharks (Carcharhinus leucas) in seasonal breeding aggregation with Sharksuckers (Echeneis naucrates) Playa del Carmen, Cancun, Quintana Roo, Yucatan Peninsula, Mexico (Caribbean Sea)

Pascal Kobeh / Close-up of the head of a White tip shark (Triaenodon obesus) laying on the bottom with a Remora (Echeneis naucrates) on its head, Sulu sea, Philippines

Doug Perrine / Dugong or Sea cow (Dugong dugon) with a Remora (Echeneis naucrates) attached to its underside, Calauit Island, off Busuanga, Calamian Islands, Palawan, Philippines.

Pascal Kobeh / Close-up of Horn-nosed / Largenose boxfish (Ostracion rhinorhynchos) with a striped remora (Echeneis naucrates) on its head at night, Sulu Sea, Philippines

Pascal Kobeh / Close-up of Horn-nosed / Largenose boxfish (Ostracion rhinorhynchos) with a striped remora (Echeneis naucrates) on its head at night, Sulu Sea, Philippines

Pascal Kobeh / Close-up of Horn-nosed / Largenose boxfish (Ostracion rhinorhynchos) with a striped remora (Echeneis naucrates) on its head at night, Sulu Sea, Philippines

Linda Pitkin / Whale shark (Rhincodon typus), with remoras (Echeneis naucrates), Mai Mai, between Triton Bay and Kaimana, West Papua, Indonesia

David Fleetham / Remora (Echeneis naucrates) free swimming, Beqa Lagoon, Fiji

David Fleetham / Remora (Echeneis naucrates) free swimming shoal, Beqa Lagoon, Fiji

David Fleetham / Sharksucker (Echeneis naucrates) cleaning scraps from inside mouth of Lemon shark (Negaprion brevirostris), unusual evidence of shark benefiting from relationship. West End, Grand Bahamas, Caribbean.