Exploring the Depths: The Fascinating World of Alicella gigantea
Far beneath the wavetops, down into the dark ocean depths, a rarely seen crustacean makes its home.
It’s called Alicella gigantea, and it’s the largest known species of amphipod, a shrimp-like species that is usually less than the size of your fingertip. By this measure, A. gigantea is a true giant in the deep sea, reaching up to 34 centimeters (13.4 inches) in length.
We used to think that these creatures were extremely rare, with very few sightings. However, new research suggests that A. gigantea might actually be widespread, inhabiting 59 percent of the world’s oceans. This apparent scarcity was more due to our limited observations than the actual population size.
Marine molecular biologist Paige Maroni of the University of Western Australia explains, “Historically, it has been sampled or observed infrequently relative to other deep-sea amphipods, which suggested low population densities. And, because it was not often found, little was known about the demography, genetic variation and population dynamics.”
The challenge in studying A. gigantea lies in its deep-sea habitat, residing in the abyssal and hadal zones below depths of 3,000 meters (9,843 feet). The lack of sunlight, extreme cold, and crushing pressures make this environment inhospitable to most life forms.
To shed light on this enigmatic creature, Maroni and her team conducted a comprehensive survey, compiling 195 records of A. gigantea from deep-sea sites across the Atlantic, Pacific, and Indian oceans. They also sequenced the genomes of specimens collected from fracture zones in the Pacific and Indian oceans.
The genetic analysis revealed surprising similarities between populations found in different seas, indicating a more connected distribution than previously thought. This suggests that A. gigantea thrives on the deep-sea floor within its depth range, covering an estimated 59 percent of Earth’s total seafloor.
Interestingly, the lack of pigmentation in A. gigantea â a rarity among amphipods â may be attributed to the absence of major predators in its environment, allowing for a widespread distribution.
As our exploration of the deep sea expands, we are uncovering the hidden secrets of creatures like A. gigantea. This research challenges the notion of its rarity and highlights the vast mysteries that lie beneath the ocean’s surface.
The study has been published in Royal Society Open Science.
