This Rare See-Through Squid Is Blinking for a Reason

There are several types of camouflage in the animal kingdom. Most people think of insects that can blend into a pile of leaves or an octopus that can match its surroundings. Transparency is a lesser-known form of camouflage, but one unusual sea creature excels at it: the glass squid. This squid can become almost completely transparent, as seen in this YouTube video, except for its eyes, which remain visible when it blinks.

The Unusual Beauty of the Glass Squid

This glass squid was filmed off the coast of Alaska, where the species is known for thriving in cold waters. The National Oceanic and Atmospheric Administration Ocean Exploration crew captured this close-up of the Taonius borealis, showing its unusual anatomy. As the squid floats downward, its red digestive organs can be seen clearly through its translucent body. Gills are located on both sides of the squid just above its mantle, and fins in this area help guide it through the water. When they float, their body cavities are filled with ammonium, giving them buoyancy and allowing the effortless movement seen in the video. In rare instances, glass squid can turn completely black, using its ink to blend in with the environment rather than remaining clear.

The most striking feature of the glass squid is its large, round eyes. Deep-sea marine animals typically have larger eyes, which help them capture more light in the dark environment. Very little sunlight penetrates the Twilight Zone, the deep-sea region where the glass squid lives. At several thousand feet below the surface, the only light comes from creatures that produce their own glow through bioluminescence. The glass squid’s eyes have multiple functions. One is to help with camouflage, as the photophores underneath its eyes are believed to aid in counter-illumination. This assists the squid in blending in with the faint light from above and avoiding predators.

Another purpose is to help the glass squid see in exceptionally dark conditions. A squid’s eyesight is comparable to—or even better than—a human’s. In a squid’s eye, photoreceptors are strategically placed at the front of the retina. This arrangement allows more light to enter and be filtered through various layers of the eye, while also preventing the squid from being blinded by intense light.

Is This Squid… Blinking?

It’s subtle, but the glass squid in this video appears to be blinking. Although adorable, the behavior serves a bigger purpose than eye lubrication. The slow blink of this squid may also be an attempt to communicate. While most cephalopods use chromatophores—cells responsible for changing color—for camouflage, the glass squid keeps its chromatophores closed. This makes them translucent instead of colored, so flashing or flickering may serve as a form of communication.

This cute wink might not serve the same purpose as it does in humans, but it does reveal something important. Most squid, including the glass squid, do not have actual eyelids; only some coastal species have a membrane that functions similarly to an eyelid. In humans, eyelids protect, lubricate, and keep foreign objects from entering the sensitive eye. In squid, these membranes can also flash to convey certain signals. We may never know what they are, but it’s a powerful tool between the animals. The most common purposes for this behavior are defense, warning, or displaying dominance. In this instance, the squid’s blinking may have been a response to the proximity of the remotely operated vehicle or another detected threat in the water.

A Remarkable Transparent Squid Discovery

In early 2025, the first-ever confirmed footage of a glacial squid (Galiteuthis glacialis) was captured in the Bellingshausen Sea near Antarctica by the R/V Falkor (too), a remotely operated vehicle from the Schmidt Ocean Institute.

Similar to the glass squid filmed near the Aleutian Islands in Alaska, the glacial squid is entirely transparent. The squid was filmed in an area that became accessible after the massive iceberg A-84 broke away from the George VI Ice Shelf on January 13, 2025, revealing a previously hidden ecosystem. Glass squids share much in common, including bioluminescent communication, their means of camouflage, and even their anatomy. Currently, there are over 60 species of glass squid, or Cranchiidae. Researchers have studied the photophores on squid eyes for years, but there is still much to learn about their function and the biology of these remarkable species.

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