Jellyfish

雪儿 · 发表于: 2011-7-8 10:54:27

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Crab Carrying Jellyfish

Photograph by Tim Laman, National Geographic

Cassiopea andromeda, the upside-down jellyfish, is named for one of Greek mythology’s treacherous queens. Cassiopeia was punished by Poseidon, who deemed that her constellation often appear upside-down in the sky. Her namesake jelly often lies on the seafloor with its mouth and arms facing the surface, which allows symbiotic algae to collect sunlight for photosynthesis and pass nutrients along to the jelly. Crabs sometimes carry these jellyfish on their backs to serve as a very effective protective shield.

雪儿 · 发表于: 2011-7-8 10:54:37

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Crab on Purple Jellyfish

Photograph by David Doubilet, National Geographic

Some animals, like these young crabs and some juvenile fish, can live unharmed among a jellyfish’s venomous tentacles. There, protected from prey, they feed on jellyfish leftovers like zooplankton or larval fish and remove parasites from their accommodating hosts.

雪儿 · 发表于: 2011-7-8 10:54:58

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Jelly-Riding Crab

Photograph by Hannah Johnson, My Shot

A crab clings to its floating host as both are swept out to sea near Wrightsville Beach, North Carolina. One role jellyfish play in the marine ecosystem is the transport of other animals across the ocean.

雪儿 · 发表于: 2011-7-8 10:55:13

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Jellyfish Lake, Palau

Photograph by Tim Laman, National Geographic

Marine scientists warn that Earth’s oceans may look increasingly like this image—teeming with ever growing populations of jellyfish. Overfishing has eliminated many of the jellies’ natural predators and competitors, while climate change is warming water temperatures to levels preferred by the invertebrates. The combination, scientists say, could produce future seas simply saturated with jellyfish.

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