Joel Sartore / Photo Ark / Yellow star coral (Xenia elongata) on the back of an empty shell, Fresno Chaffee Zoo, California. Captive.

Joel Sartore / Photo Ark / Philyra spider crab (Micippa philyra) portrait, from the Gulf of Oman, UAE.

Joel Sartore / Photo Ark / Red Sea ghost crab (Ocypode saratan) portrait, Sharjah Aquarium, UAE. Captive.

Joel Sartore / Photo Ark / Blue land crab (Cardisoma guanhumi) portrait, near Vero Beach, Florida, USA.

Joel Sartore / Photo Ark / Blue land crab (Cardisoma guanhumi) portrait, near Vero Beach, Florida, USA.

Joel Sartore / Photo Ark / Pocketbook mussel (Lampsilis ovata) female, from the Clinch River, Virginia. This is a female, displaying her mantle lure, made to mimic a bait fish. Aquatic Wildlife Conservation Center, Virginia, US...

Joel Sartore / Photo Ark / Vamprie crab (Geosesarma dennerle) portrait, from a private collection. Captive, occurs in Java.

Joel Sartore / Photo Ark / Trumpet green coral (Caulastraea curvata) portrait, The Butterfly Pavilion, Colorado. Captive.

Joel Sartore / Photo Ark / Rough scallop (Aequipecten muscosus) portrait, Gulf Specimen Marine Lab, Florida, USA. Captive.

Joel Sartore / Photo Ark / Group of Rough scallops (Aequipecten muscosus) portrait, Gulf Specimen Marine Lab, Florida, USA. Captive.

Joel Sartore / Photo Ark / Central American mud turtle (Kinosternon angustipons) male, underwater portrait, Turtle Island, Austria. Captive, occurs in Central America.

Joel Sartore / Photo Ark / Malayan snail-eating turtle (Malayemys macrocephala) male, underwater portrait, Turtle Island, Austria. Captive, occurs in Southeast Asia.

Doug Perrine / Knobby sea stars (Pentaceraster cumingi) aggregating on seabed, probably gathering for mating, Makako Bay, North Kona, Hawaii, Pacific Ocean.

Doug Perrine / Knobby sea stars (Pentaceraster cumingi) aggregating on seabed, probably gathering for mating, Makako Bay, North Kona, Hawaii, Pacific Ocean.

Doug Perrine / Knobby sea stars (Pentaceraster cumingi) aggregating on seabed, probably gathering for mating, Makako Bay, North Kona, Hawaii, Pacific Ocean.

Doug Perrine / Hawaiian long-armed sand octopus (Thaumoctopus, Abdopus, or Macrotritopus sp.) unidentified species possibly endemic to Hawaii, swimming by jet propulsion, jetting water through its funnel, Honokohau,...

Doug Perrine / Group of Freckled driftfish (Psenes cyanophrys) swimming alongside tentacles of Pelagic jellyfish (Thysanostoma sp.), Pawai Bay, North Kona, Hawaii, Pacific Ocean.

Doug Perrine / Hawaiian long-armed sand octopus (Thaumoctopus, Abdopus, or Macrotritopus sp.) unidentified species possibly endemic to Hawaii, pair displaying mating behaviour, dark maroon colour pattern around eyes...

Doug Perrine / Hawaiian long-armed sand octopus (Thaumoctopus, Abdopus, or Macrotritopus sp.) unidentified species possibly endemic to Hawaii, perched above its burrow with eyes raised for viewing its surroundings,...

Doug Perrine / Pelagic jellyfish (Thysanostoma sp.) swimming in open water accompanied by group of Freckled driftfish (Psenes cyanophrys), Pawai Bay, North Kona, Hawaii, Pacific Ocean.

Doug Perrine / Hawaiian long-armed sand octopus (Thaumoctopus, Abdopus, or Macrotritopus sp.) unidentified species possibly endemic to Hawaii, perched on tips of arms, Honokohau, North Kona, Big Island, Hawaii, Paci...

Doug Perrine / Pelagic jellyfish (Thysanostoma sp.) swimming in open water accompanied by group of Freckled driftfish (Psenes cyanophrys), Pawai Bay, North Kona, Hawaii, Pacific Ocean.

Doug Perrine / Bigeye emperor (Monotaxis grandoculis) portrait, Honokohau, North Kona, Hawaii, Pacific Ocean.

Doug Perrine / Schooling Bigeye emperors (Monotaxis grandoculis), Honokohau, North Kona, Hawaii, Pacific Ocean.

Doug Perrine / Pelagic jellyfish (Thysanostoma sp.) swimming in open water accompanied by group of Freckled driftfish (Psenes cyanophrys), Pawai Bay, North Kona, Hawaii, Pacific Ocean.

Doug Perrine / Bigeye emperor (Monotaxis grandoculis) sub-adult, portrait, Honokohau, Kona, Hawaii, Pacific Ocean.

Doug Perrine / Pacific agile chromis (Pycnochromis pacifica) juvenile, portrait, Honokohau, North Kona, Hawaii, Pacific Ocean.

Doug Perrine / Hawaiian longfin anthias (Pseudanthias hawaiiensis) male, portrait, Pawai Bay, North Kona, Hawaii, Pacific Ocean.

Doug Perrine / Flame angelfish (Centropyge loriculus) swimming on coral reef, with Finger coral (Porites compressa) behind, Ho'okena, South Kona, Hawaii, Pacific Ocean.

Doug Perrine / Banded angelfish (Apolemichthys arcuatus) swimming over coral reef, Kaiwi Point, North Kona, Hawaii, Pacific Ocean.

Pal Hermansen / King eiders (Somateria spectabilis), Eiders (Somateria mollissima) and Gulls (Larus sp.) in fishing harbour. During the winter time the birds gather in harbour to feed on fish waste, Batsfjord, Finnma...

Pal Hermansen / King eider (Somateria spectabilis) on water in fishing harbour, Batsfjord, Finnmark, Norway. February.

Pal Hermansen / Aerial view of wind turbines at Great Gabbard offshore wind park, off the coast of Suffolk, England, UK, North Sea. October, 2022.

Pal Hermansen / Stranded iceberg in Disko bay at night, Greenland.