During a dive off the coast of Southern California in 1979, the DSRV Alvin (Deep Submergence Rescue Vehicle) made its way through dim, oxygen-deprived waters. As it cautiously maneuvered the murky darkness, a mysterious red light flickered in the distance.
As the manned submersible inched closer, what appeared to be a jellyfish at first glance was, in fact, a creature that is later identified as the bloody-belly comb jelly or Lampocteis cruentiventer. The name Lampocteis cruentiventer combines the Ancient Greek “lampós” (bright) and “kteís” (comb), referencing the iridescence from its comb rows. The Latin-derived cruentiventer, from “cruentus” (blood-red) and “venter” (belly), describes its vividly red stomach.
Afterward, from 1991 to 1999, bloody-belly comb jelly underwent a detailed study at MBRI (Monterey Bay Aquarium Research Institute), during which additional specimens were collected at a depth of 679 meters within the Monterey Submarine Canyon.
Although the bloody jelly resembles a jellyfish, it is, in fact, a ctenophore, or comb jelly. These organisms differ from jellyfish because they lack nematocysts, the characteristic stinging cells in cnidarians such as jellyfish and corals.
Here are two fascinating facts about this captivating creature and how it evolved to survive its challenging habitat—the ocean’s twilight zone, which is between 820 to 4900 feet below sea level.
1. Red Camouflage Helps It Stay Undetected
Bloody-belly comb jellies are distinguished by their red stomachs. The intriguing red color of this jelly serves multiple purposes related to its survival and adaptation.
In the deep-sea environment where red light is scarce due to rapid absorption and scattering by water molecules, organisms with red pigmentation can effectively blend in with their surroundings. Its red color appears almost black, rendering it nearly invisible to its predators and prey alike.
Additionally, some of the deep-sea inhabitants targeted for food by the bloody-belly comb jelly possess the ability to be bioluminescent; that is, they can produce their own light. The red gut of this translucent jelly helps mask its digesting food and avoid detection. Otherwise, there’s a risk of its recent meal illuminating it internally, potentially attracting attention from predators. Its red color also enhances its effectiveness to go unseen by potential prey items.
2. Ciliary Movement Is Linked To Refraction
Comb jellies are the largest animals to have entirely ciliary locomotion and bloody-bellies can grow up to six inches. They also possess eight rows of hair-like cilia, called ctenes, which serve for both swimming and feeding.
Additionally, the rows of minute hairs covering their bodies contribute to the creatures’ shiny and colorful appearance. When white light interacts with the surface of bloody-bellies, the rhythmic beating of their comb rows causes the light to diffract, resulting in a stunning display of vibrant colors resembling a rainbow.
This captivating phenomenon is attributed to the jelly’s exceptionally bright appearance, primarily due to its extra-broad and highly iridescent ctene plates. Moreover, the cilia possess the remarkable ability to refract and disperse light, enhancing the rainbow effect.
This light production can serve various purposes, such as communication, attracting prey or confusing predators. While the exact mechanism of light production may vary among species, the coordinated movement of cilia is also responsible for generating bioluminescent displays in certain ctenophores.
There is a concerning prevalence of plastic pollution in the deep sea habitats where comb jelly lives, and it poses significant risks to these vital marine organisms. The presence of microplastics has been found in their digestive systems, suggesting that our waste is infiltrating their environment.
Given that ctenophores, such as the bloody-belly comb jelly, are likely to transfer microplastics to humans through the food chain, this is a concern that warrants close attention. As these organisms inhabit various levels of the marine ecosystem, they can accumulate microplastics which may then be passed on to larger predators, including fish that are commonly consumed by humans. Understanding the role of ctenophores in this cycle highlights the broader environmental impact of pollution and underscores the urgency of addressing microplastic contamination in our oceans.
