This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Thousands of meters below the waves off Australia's east coast, far beyond where sunlight can reach, a stunning light show takes place in the dark. Two species of long-legged creatures emitting a blue glow.
During a deep-sea marine survey in 2017, scientists observed bioluminescence in the giant sea spiders Colossendeis tasmanica and Colossendeis minor. This was the first time the phenomenon had been formally documented and photographed in these two species. There have been a few previous reports of glowing sea spiders, including observations of a blue light along the undersides of specimens collected in the Indian Ocean during the late 19th century.
However, it was unclear whether the spiders made their own light or had just picked up glowing mucus from brushing against organisms like deep-sea corals. And while many organisms in the deep ocean produce their own light, very little was known about bioluminescence in sea spiders. During the survey, researchers collected several deep-sea creatures.
These included seven C. tasmanica and two C. minor individuals collected from depths between 1,006 meters (3,301 feet) and 4,977 meters (16,329 feet). To test whether the sea spiders were actually producing their own light, the team led by Dr. Jerome Mallefet from UCLouvain in Belgium first conducted analyses on the ship.
What they discovered is explored in detail in a paper published in the journal Deep-Sea Research Part I. They placed the animals in a dark room where their legs began to glow after being stimulated by gentle pinching or chemical triggers. The researchers then photographed the light, measured its intensity and color spectrum and tested how different leg segments reacted.
C. tasmanica emitted a deep-blue light (449 nanometers) only from its legs, which glowed brightest at the tips (propodus) and faded toward the body. The chemically triggered glow could last for five to 10 minutes, but the manually triggered glow was weaker and lasted from a few seconds to more than two minutes. But they didn't know the exact chemical reaction producing the light or which specific cells were responsible inside the legs.
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