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Red Sea Urchins, British Columbia
Photograph by Paul Nicklen, National Geographic
Visually arresting, hazardous to swimmers, and—to some cultures—delicious, sea urchins are also revealing new information to the scientists who study them.
Here, red sea urchins carpet a kelp forest off British Columbia. The marine invertebrates are important links in the marine food chain. Fish pick at the urchins, which feed on bits of algae.
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Sea Urchin, British Columbia
Photograph by Paul Nicklen, National Geographic
The vivid purple spines of this sea urchin from God’s Pocket Marine Provincial Park, British Columbia, help it move along the seafloor, as do hydraulically operated tube feet.
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Snapper Eating Sea Urchin
Photograph by Brian J. Skerry, National Geographic
Restoring balance between predator and prey, once overfished snapper eat sea urchins that had nearly denuded the reefs at Goat Island reserve in New Zealand.
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Sea Urchins, British Columbia
Photograph by Paul Nicklen, National Geographic
A nontoxic dye highlights water currents surrounding sea urchins off Vancouver Island, British Columbia. These small, spiny echinoderms are found in oceans all over the world.
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Sea Urchin, Hawaii
Photograph by Julie Wynne, My Shot
A sea urchin’s long, moveable spines protect it from predators in the waters off Hawaii. In the first century A.D., Pliny the Elder wrote of using sea urchin ashes to treat baldness.
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Fire Urchin, Indonesia
Photograph by Tim Laman, National Geographic
The spines of a fire urchin form a multicolored flower off Komodo Island, Indonesia. The blue swellings on the tip of each spine are filled with venom.
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Sea Urchin, Bonaire Island
Photograph by George Grall, National Geographic
A sea urchin is nestled in a coral formation off Bonaire Island. Urchins feed on algae and invertebrates—a recent study found that the sound of their teeth scraping on reefs can cause a rise in ocean noise.
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Sea Urchin, Channel Islands
Photograph by Lindsey Hesla, My Shot
Sea urchins brandish their spines on the seafloor near the Channel Islands. Scientists recently discovered that the eyeless invertebrates “see” by detecting light with their spines.
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Green Sea Urchins, Alaska
Photograph by Joel Sartore, National Geographic
Green sea urchins, chitons, and sea stars cluster in a tidal pool off Alaska’s Aleutian Islands. Sea urchins and sea stars are close relatives.
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Pencil-Spined Urchin, Kingman Reef
Photograph by Brian J. Skerry, National Geographic
The spines of the omnivorous pencil-spined urchin extend outward from its body. There are some 700 species of sea urchins worldwide.
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Fire Urchin, Papua New Guinea
Photograph by David Doubilet, National Geographic
The bright red color of a fire urchin warns predators that its spines are poisonous. Sea otters are the major predators of sea urchins.
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