Bioluminescence is common in deep-sea shrimp

Recent research has revealed a fascinating phenomenon: bioluminescence is more prevalent among deep-sea shrimp than previously recognized. The study has identified 157 species with the ability to emit light, expanding our understanding by 65% compared to earlier estimates.

These shrimp illuminate the ocean depths in various ways – some by ejecting glowing secretions, others through sophisticated organs in their bodies designed specifically for light production, and a few employing both methods.

The roles of bioluminescence in shrimp

The purpose behind these luminous displays is as varied as the methods themselves. Bioluminescence serves multiple functions, according to Stormie Collins, a Ph.D. student at FIU, and her mentor, Professor Heather Bracken-Grissom.

For some shrimp, it’s a form of camouflage; for others, a means of defense; and for many, it’s a way to communicate in the pitch-black environment of the deep sea.

Adapting to the darkness of the deep sea

“The ocean is the largest ecosystem on Earth, comprising over 99% of all habitable space on the planet, of which most is dark, expansive, and structured only by chemical and physical properties of the water column,” wrote the study authors.

“The deep sea begins in waters 200–1000 m in depth, known as the mesopelagic or twilight zone. The twilight zone is an extremely light-limited environment, as downwelling sunlight attenuates rapidly with depth.”

“Waters below 1000 m are referred to as the bathypelagic or midnight zone due to the complete absence of downwelling sunlight. Survival in the deep sea has resulted in the evolution of a suite of morphological features, for example, the ability to produce light through a process called bioluminescence.”

Expanding the known range of bioluminescence

The researchers utilized a combination of direct observation during deep-sea expeditions, literature review, and accounts from other studies.

“We report bioluminescence in 157 species of decapod shrimps spanning 12 families – an increase in bioluminescent decapod species of 65% from a previous review which reported 55 species spanning five families,” noted the researchers.

Source of bioluminescence in shrimp

Previously, it was thought that shrimp primarily used luminous secretions for bioluminescence. The new data, however, show a shift towards more species utilizing light organs embedded within their tissue, known as photophores.

“We report photophores in the family Pasiphaeidae based on personal observations of light organs in live specimens, making this the first record of dermal light organs in this family, and increasing the number of representative caridean families with dermal photophores,” wrote the study authors. 

“Previously, luminous secretions were thought to be the most common form of bioluminescence in decapod shrimps. By contrast, we find dermal photophores to be the most common light organ type across decapod species.”

The mystery and beauty of bioluminescence

Despite these advances, much about bioluminescence remains enigmatic, particularly among deep-sea creatures.

“Bioluminescence is the universal language of light in the deep sea,” explained Bracken-Grissom. She emphasized the importance of continued research to unravel how these creatures use light to survive in such an extreme environment.

Each sea expedition brings to light new and exciting discoveries, enriching our understanding of one of nature’s most mysterious phenomena.

Bracken-Grissom and her team are committed to developing innovative research methods to further explore and appreciate the complex beauty of bioluminescent shrimp.

This commitment not only advances the field of sensory biology but also fosters a deeper appreciation for these creatures beyond their culinary delights.

The imperative of continued marine research

This latest inquiry into the luminous life of deep-sea shrimp illustrates the vast potential and imperative need for ongoing studies in this area.

The research builds on previous findings and significantly increases the known diversity of bioluminescent life forms. The scientists believe there are still more species waiting to be discovered.

“We are learning that bioluminescence is much more common than previously thought, not only within shrimps but across all deep-sea animals,” said Collins.

“Future research directions include experimental studies investigating the visual capacity of deep-sea shrimps, phylogenetic studies investigating the evolution of bioluminescence across decapod taxa, and molecular studies investigating extraocular photosensitivity,” concluded the study authors.

The study is published in the journal Biological Reviews.

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