Joel Sartore / Photo Ark / Three Spotted jellyfish (Mastigias papua) portrait, Monterey Bay Aquarium, California. Captive, occurs in Indo-Pacific.

Joel Sartore / Photo Ark / Flat-spined brittlestar (Ophiopteris papillosa) portrait, Butterfly Pavilion, Colorado. Captive, occurs in eastern Pacific Ocean.

Joel Sartore / Photo Ark / Two Flat-spined brittlestars (Ophiopteris papillosa) portrait, Butterfly Pavilion, Colorado. Captive, occurs in eastern Pacific Ocean.

Joel Sartore / Photo Ark / Two Spotted jellyfish (Mastigias papua) portrait, Omaha's Henry Doorly Zoo and Aquarium, Nebraska. Captive, occurs in Indo-Pacific.

Joel Sartore / Photo Ark / Violet-spotted reef lobster (Enoplometopus debelius) portrait, Pure Aquariums, Nebraska. Captive, occurs in Indo-Pacific.

Joel Sartore / Photo Ark / Edible sea cucumber (Holothuria edulis) portrait, Sharjah Aquarium, United Arab Emirates. Captive, occurs in Indo-Pacific.

Joel Sartore / Photo Ark / Leopard sea cucumber (Holothuria pardalis) portrait, Sharjah Aquarium, United Arab Emirates. Captive, occurs in Indo-Pacific.

David Fleetham / Aerial view of Pygmy blue whale (Balaenoptera musculus brevicauda) gliding below the surface, East Timor, Indian Ocean. Endangered.

David Fleetham / Sperm whale (Physeter macrocephalus) swimming off the coast of East Timor, Indian Ocean. Endangered.

David Fleetham / Whale shark (Rhiniodon typus) swimming close to surface, off the coast of Baucau, East Timor, Indian Ocean. Endangered.

David Fleetham / Checkerboard wrasse (Halichoeres hortulanus) following a hunting Dash-dot goldfish (Parupeneus barberinus) to snatch left-over prey, Yap, Micronesia, Pacific Ocean.

David Fleetham / Sergeant major damsels (Abudefduf vaigiensis) juvenile school sheltering around buoy covered in pelagic Gooseneck barnacles (Lepas anatifera), East Timor, Indian Ocean.