If you were to think about the strangest creatures on the planet, you probably wouldn't imagine that there's a practically invisible octopus swimming in the abyss. This isn't science fiction, but a fascinating reality that modern oceanography has begun to unveil, showing us beings that seem to be made of glass and that challenge our understanding of marine biology.
Recently, several expeditions have focused on these gelatinous wonders that inhabit total darkness. From the findings of the Schmidt Ocean Institute to research in the Galápagos Islands, we have encountered specimens that don't fit into any previous catalog , forcing scientists to rethink how adaptations work on the ocean floor.
The fascinating glass octopus
One of the most surprising milestones has been the filming of the so-called glass octopus. This creature, which inhabits the depths of the Pacific Ocean between 200 and 1.000 meters deep, is a spectacle of nature due to its almost transparent body. When observing it, the only things that truly stand out are its eyes and optic nerve, giving it an ethereal and ghostly appearance.
This animal is so unusual that it was first captured on video in 2021, leaving experts astonished by its rectangular eyes . This transparency is no accident, but a brilliant evolutionary adaptation for camouflage in absolute darkness, where any trace of color could betray it to a predator.
Microeledone galapagensis: a taxonomic enigma
Descending even further, specifically to about 1.773 meters below Darwin Island in the Galápagos, another disruptive discovery emerged: Microeledone galapagensis . This cephalopod, formally described in the journal Zootaxa by researchers from the Field Museum of Chicago and other institutions, broke the mold, as it resembles nothing known within its genus.
At first glance, it looks like a small, somewhat squat octopus with short arms and a limited number of suckers. What's truly striking is that its dorsal skin is almost entirely devoid of pigment, resulting in a translucent surface . While most inhabitants of the deep use dense chromatophores to regulate their visibility, this specimen opted for near-total transparency on its exterior.
However, the real surprise came with the use of microCT (computed tomography). By analyzing its interior, scientists discovered that the dorsal muscles of the mantle have very intense pigmentation. This means that the animal exhibits reverse countershading : it is light on the outside and dark on the inside, an anatomical architecture that has no clear equivalent in other octopus groups.
The biological key: heterochrony and neoteny
To explain why this adult octopus looks like a larva, experts use the concept of heterochrony. Essentially, this occurs when there are changes in the rate of embryonic development, causing the adult to retain typical juvenile characteristics —a phenomenon also known as neoteny. It's as if the animal's biological clock stopped prematurely.
This theory is reinforced by other critical anatomical absences. Microeledone galapagensis lacks an ink sac and also a crop diverticulum. These two features are fundamental, as they were considered defining characteristics of the Megaleledonidae family. Their absence necessitates the reclassification of an entire family of cephalopods.
Mysteries that still remain to be solved
Despite these advances, many pieces of the puzzle still don't fit. Because the specimens were collected from a single area near Darwin Island, we don't know if this species is distributed throughout the eastern Pacific or if it's specific to that area. Furthermore, since the description is based on morphology, in-depth molecular analysis is needed to confirm its exact position in the phylogenetic tree.
Nothing is known about what it eats, how it behaves, or how it reproduces. However, this is typical in deep-sea taxonomy; describing a species is only the first step on a path that can last decades. The fact that the Galápagos Islands continue to hold these secrets reminds us that the ocean is the ocean of our world.
The existence of these creatures, from the glassy transparency of the glass octopus to the strange inverted anatomy of Microeledone galapagensis, demonstrates that life in the abyss continues to surprise us with extreme adaptations and evolutionary processes such as neoteny, making it clear that we still have much to discover in the deepest waters of the Pacific.
