A tiny blue octopus that could fit in the palm of your hand has just been confirmed as an entirely new species. It was spotted nearly 1,800 meters below the surface near the Galápagos Islands, and its striking blue colour—one of the rarest in nature—may be the key to its survival.
The discovery, published in the journal Zootaxa, describes Microeledone galapagensis, a palm-sized cephalopod found near Darwin Island in the northern Galápagos archipelago. It was first filmed by a remotely operated vehicle during a deep-sea expedition aboard the E/V Nautilus in 2015, but it took nearly a decade of painstaking work to confirm that it was new to science.
Here is the story of the little blue octopus that almost slipped away.
A Golf-Ball Sized Creature With a Rarest of Colours
The octopus is small enough to fit between the bottom of your palm and the first knuckle of your middle finger, or roughly the size of a golf ball. Its body is squat, its arms are short and stubby—only about three to four centimetres long, with roughly 30 suckers each—and its skin is smooth and largely pigment-free.
But what caught the researchers’ attention was its colour. The octopus has a light blue back and a dark purple inner mantle, a combination that is exceedingly rare in the natural world. As National Geographic put it, its blue hue is “the rarest colour in nature”.
The colouration is not just beautiful. It appears to be a survival strategy.
The Science of “Reverse Countershading”
The octopus exhibits a phenomenon called “reverse countershading”—the opposite of the camouflage strategy used by most marine animals. Typically, animals are darker on top and lighter underneath, blending with the seafloor below and the light above.
This octopus does the opposite. Its pale back has almost no pigment, while the inside of its mantle is deep purple. Researchers believe this helps it hide while it forages.
The octopus uses its short, stubby arms to dig through sediment on the seafloor in search of prey. When it disturbs the sediment, it may stimulate bioluminescent organisms to glow. The dark webbing on its arms could shield that light from predators while the octopus eats, and pigment cells inside its body could block any glow from within.
It is a small, elegant adaptation for a life spent in the dark.
The Decade-Long Journey From Discovery to Diagnosis
The octopus was first spotted in 2015, but identifying it as a new species was not straightforward. The expedition team collected a single specimen—a female—but paperwork and logistics delayed its arrival at the Field Museum in Chicago until 2022.
When octopus specialist Janet Voight, curator emerita of invertebrates at the Field Museum, finally examined the specimen, she faced a dilemma. Describing a new octopus species normally requires dissection—cutting open the animal to examine its mouth, beak, and teeth. But with only one specimen, and one that had been preserved in formaldehyde that had not fully penetrated its egg-filled body, dissection was risky.
“If you make the wrong cut or tear something, it’s gone forever,” Voight said. “The cost of going to sea is just astronomical, and the chances of finding another one and successfully collecting it are just not high”.
Her solution was to use the Field Museum’s CT scanner. Thousands of X-ray images were compiled into a 3D model, allowing her to examine the octopus’s internal anatomy without destroying the specimen. It became the first octopus species described using CT scanning alone.
The scans confirmed what Voight had suspected: this was not a juvenile. It was a fully grown adult with a complete set of arm suckers and 13 eggs in its ovaries. Its small size, the researchers suggest, may be an adaptation that allows it to reproduce faster than larger relatives by shortening the time from hatching to first eggs.
A Single Specimen, a World of Unknowns
Microeledone galapagensis belongs to the genus Microeledone, which until now contained only one other species: Microeledone mangoldi, found in the waters off New Caledonia in the South Pacific. The two species share smooth skin, large funnel organs, and similar arm sucker counts, but they differ in where their colour is concentrated.
The fact that these two species are separated by thousands of kilometres of open ocean suggests that other species may live in the vast, unexplored waters between them.
“The Pacific Ocean is unimaginably immense, and every part of it contains animal life from the surface to the seafloor,” Voight said. “This specimen highlights that unknown diversity”.
Why This Tiny Octopus Matters
The discovery is a reminder of how little we know about the deep sea—and how much is at stake.
“These are little octopuses that live in the deep sea and hardly anybody on Earth has ever gotten to see them,” Voight said. “I just feel lucky that I got to work with them”.
The Galápagos deep-sea ecosystems remain largely unexplored, and each new species helps scientists better understand these hidden worlds and why protecting them matters. The little blue octopus is not just a scientific curiosity. It is a symbol of the vast, unknown biodiversity that exists in the ocean’s twilight zone—a realm that is increasingly threatened by deep-sea mining, trawling, and climate change.
It is also a testament to the patience of science. A creature the size of a golf ball, spotted for a few seconds in 2015, took nearly a decade to be formally recognised. And it was identified not by cutting it open, but by looking inside it with X-rays—a technique that preserved the specimen for future study.
The octopus is small. Its story is not.
