A giant California sea cucumber (Parastichopus californicus) photographed at Monterey Bay Aquarium in California
A giant California sea cucumber (Parastichopus californicus) photographed at Monterey Bay Aquarium in California
Photograph by Joel Sartore, National Geographic Photo Ark

Sea Cucumbers

Common Name:
Sea Cucumbers
Scientific Name:
Holothuroidea
Type:
Invertebrates
Diet:
Omnivore
Average Life Span In The Wild:
5 to 10 years
Size:
0.75 inches to 6.5 feet

Sea cucumbers are echinoderms—like starfish and sea urchins. There are some 1,250 known species, and many of these animals are indeed shaped like soft-bodied cucumbers. All sea cucumbers are ocean dwellers, though some inhabit the shallows and others live in the deep ocean. They live on or near the ocean floor—sometimes partially buried beneath it.

Feeding

Sea cucumbers feed on tiny particles like algae, minute aquatic animals, or waste materials, which they gather in with 8 to 30 tube feet that look like tentacles surrounding their mouths. The animals break down these particles into even smaller pieces, which become fodder for bacteria, and thus recycle them back into the ocean ecosystem. Earthworms perform a similar function in terrestrial ecosystems.

As Prey and Food

Sea cucumbers, particularly eggs and young larvae, are prey for fish and other marine animals. They are also enjoyed by humans, especially in Asia, and some species are farmed as delicacies.

Defensive Adaptations

When threatened, some sea cucumbers discharge sticky threads to ensnare their enemies. Others can mutilate their own bodies as a defense mechanism. They violently contract their muscles and jettison some of their internal organs out of their anus. The missing body parts are quickly regenerated.

Reproduction

Sea cucumbers can breed sexually or asexually. Sexual reproduction is more typical, but the process is not very intimate. The animals release both eggs and sperm into the water and fertilization occurs when they meet. There must be many individuals in a sea cucumber population for this reproductive method to be successful. Indeed, many parts of the deep ocean host large herds of these ancient animals, grazing on the microscopic bounty of marine waters.

This photo was submitted to Your Shot, our photo community on Instagram. Follow us on Instagram at @natgeoyourshot or visit us at natgeo.com/yourshot for the latest submissions and news about the community.
This photo was submitted to Your Shot, our photo community on Instagram. Follow us on Instagram at @natgeoyourshot or visit us at natgeo.com/yourshot for the latest submissions and news about the community.
Photograph by ferial monsef, National Geographic Your Shot

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