Shane Gross / Pelagic thresher shark (Alopias pelagicus) cleaned by a Bluestreak cleaner wrasse (Labroides dimidiatus) at Monad Shoal off Malapascua Island, Philippines.

Shane Gross / Pelagic thresher shark (Alopias pelagicus) being cleaned by a bluestreak cleaner wrasse (Labroides dimidiatus) at Monad Shoal off Malapascua Island, Philippines.

David Fleetham / Cleaner wrasse (Labroides dimidiatus) swimming alongside Golden damsel (Amblyglyphidodon aureus) looking for parasites, Fiji, Pacific Ocean.

Alex Mustard / Harlequin sweetlips (Plectorhinchus chaetodonoides) cleaned by a pair of bluestreak cleaner wrasse (Labroides dimidiatus). South Atoll, Tubbataha Atolls, Tubbataha Reefs Natural Park, Palawan, Philipp...

Alex Mustard / Bluestreak cleaner wrasse (Labroides dimidiatus) cleans among the sharp teeth of a predatory roving coral grouper (Plectropomus pessuliferus) beneath an overhang on a coral reef. Ras Mohammed National...

Tony Wu / Bluestreak cleaner wrasse (Labroides dimidiatus) cleaning Luna lionfish (Pterois lunulata). Shizuoka Prefecture, Honshu, Japan. June.

Alex Mustard / Reef manta (Mobula alfredi) female swimming close to a coral reef, while cleaner wrasse (Labroides dimidiatus), tiny by comparison, pick parasites from her lips. Misool, Raja Ampat, West Papua, Indone...

Shane Gross / Pelagic thresher shark (Alopias pelagicus) cleaned by Bluestreak cleaner wrasse (Labroides dimidiatus) at Monad Shoal off Malapascua Island, Philippines.

Alex Mustard / Bluestreak cleaner wrasse (Labroides dimidiatus) attends to a Clark's anemonefish (Amphiprion clarkii) at a cleaning station on a coral reef. It is unusual to see an anemonefish at a cleaning stat...

Alex Mustard / Reef manta (Mobula alfredi) at a cleaning station with Cleaner wrasse (Labroides dimidiatus). South Ari Atoll, Maldives. Indian Ocean.

Richard Robinson / Orbicular damselfish (Amblyglyphidodon orbicularis) cleaned by the Striped Cleaner Wrasse (Labroides dimidiatus) at Yagasa Lagoon, Lau Island Group, Fiji.

Richard Robinson / Egghead Parrotfish (Scarus oviceps) cleaned by a Striped Cleaner Wrasse (Labroides dimidiatus) Vatoa Island / Turtle Island by Captain Cook, Lau Island Group, Fiji.