Like jellyfish, fungi, sea worms, and fireflies, some species of sea cucumbers glow in the dark. A team of researchers from Nagoya University in Japan have found that 10 known deep-sea species are bioluminescent in their natural habitats. The findings are part of a new textbook called The World of Sea Cucumber published on November 10.
[Related: The deepest known ocean virus lives under 29,000 feet of water.]
There are roughly 1,200 species of sea cucumbers. These marine invertebrates are found in every ocean on Earth, but they are best represented in the western Pacific and Indian Ocean. They generally live in shallow waters, but some species live at depths of thousands of feet deep. Most closely related to sea urchins, sea stars (aka starfish), sea lilies, and sand dollars, these bottom-dwellers range from as small as one inch long up to six feet. Some sea cucumbers are also known to shoot out a tangle of sticky, noodle-like goo from their butts when provoked.Â
The new textbook takes readers deep underwater and discusses the bioluminescent properties of some of these sea cucumbers. According to NOAA, the light emitted by bioluminescent animals is produced by energy released from interior chemical reactions that are sometimes ejected from the organism. Its function is still a mystery, but it is generally used to ward off or evade predators, find food, or as a form of communication.Â
The authors drew on previous sea cucumber research to highlight the differences between the shallow-dwelling and a bit more drab species and their brilliantly glowing deep-sea relatives. The book also shows the evolution of sea cucumbers from the Jurassic era roughly 180 million years ago up to the present day.Â
To uncover the 10 bioluminescent sea cucumber species, the team deployed a remotely operated vehicle about 3,280 feet below the surface of Monterey Bay, California. The vehicle was equipped with a very sensitive and an arm that was robotically…
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