Are there transparent animals? » ABC of science

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Many animals are transparent, especially underwater, where transparency helps aquatic creatures hide from predators.

All animals aspire to one thing: to survive. As humans, we may not always have to watch our backs, but other animals certainly do. This is especially true for those who top the list of predators around them. Survival is difficult because not everyone can be at the top of the food chains.

Naturally, some animals have found a clever way to trick their predators. They’ve camouflaged themselves, but that has its own flaws too: what if there’s no substrate to blend into, leaving them absolutely nowhere to hide?

To combat this crisis, some animals have evolved to simply hide in plain sight!

(Photo credit: tsuponk/Shutterstock)


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Transparent… but how?

If being transparent offers high-level protection against predators who want to stalk you, why aren’t we constantly running into invisible creatures?

Animals are made up of many organs and tissues, which have their own thickness and chemical composition. As a result, an animal’s body is far from something that would let light through, without that light being first reflected, absorbed, scattered, or refracted.

Water dwellers have a clear advantage in terms of transparency, as their bodies are almost all made up of water. Being transparent as an earth dweller, however, is much more difficult, due to refractive indices (a fancy word that explains how light slows down as it enters a particular medium).

The air we breathe has a very low refractive index, but water has a significantly higher value. Think of looking at a pint glass on a sunny day…there’s probably a reflection on it, right? What if you put the same piece of glass in the water? Call it a crystal, because it’s just as clear.

Woman underwater with jellyfish in blue ocean. Lady glides underwater

Transparency is much more common underwater (Photo credit: Wonderful Nature/Shutterstock)

Therefore, if water has a high refractive index, like the material that some ocean animals are made of, then there is virtually no light scattering. Suddenly, poof! You can no longer see them.

When you think about it, transparency is an ideal form of camouflage. Check out these animals, but you’ll have to look closely or you’ll miss them completely!

Animals that use transparency to hunt

The ghost fish

Macropinna Microstomy, also called barrel or ghost fish, was aptly described as a fish with “a transparent bubble-like astronaut helmet”, by marine biologist Dr. Helen Scales. There is good reason for this distinction, as these fish have dark, opaque bodies, but a clear head through which you can see his eyes and other olfactory organs.

Deep Sea Barreleye Fish 3d Rendering

The ghost fish (Photo credit: 3dsam79/Shutterstock)

Spookfish have glowing green orbs for their eyes and they always gaze upwards, hoping to catch the shadows cast by their prey (crustaceans), when the shimmering sunlight hits them. Now, if you’re wondering how they eat with their eyes up, they just rotate them in their transparent fabric dome. Still feeling scared?

Animals that use transparency to escape predators

European eels

These eels will begin their young lives as transparent bands before their bellies and sides change to a brownish-yellow color. Spending their young lives in transparency can ensure their survival until they can fend for themselves. Once they have become sexually mature, they are called “silver eels”.

Major Salpa

They are rare marine invertebrates found in the cooler waters of the Southern Ocean. They probably need transparent bodies more than any other fish because they feed on plankton on the surface of the water, which makes them extremely susceptible to predators. The Salpa is a jellyfish-like animal covered in a transparent sheath; under this sheath are its muscles, intestines and other organs.

Transparent Immortal Jellyfish

Turritopsis dohrnii are also transparent and a bit smaller than your small fingernail (0.18 inches). A bright red stomach emerges in the center of its transparent bell whose edges are lined with nearly a hundred white tentacles.

Immortal, Jellyfish, Isolated

The immortal jellyfish (Photo credit: Rebecca Schreiner/Shutterstock)

Not only do they exploit their transparency to evade predators, but they also hit the jackpot when it comes to survival. It’s one thing to come out of harsh environments alive, but it’s another thing to hit the reset button in the face of your inevitable death. That’s right, these jellyfish never die, but are instead re-born at the polyp stage and live on forever!

ghost shrimp

Ghost Shrimp (Palaemonetes sp.) have a nice name, given their transparency! We can only see Orange or yellow spot in the center of their tails. Jhe females are so transparent that their green eggs are clearly visible in their body after reproduction.

glass octopus

Vitreledonella richardi Where the rare glass octopus, are an almost entirely transparent species except for the optic nerve, eyeballs, and digestive tract. They have long, elongated eyes with a centralized lens, which could be useful in minimizing the silhouette of the eyes when observed from below.

cockatoo squid

Also known as glass squids, these cephalopods are so transparent that the only hints of color you’ll see in them are from their eyes and some visceral nuclei. However, the peculiarity of this species of squid is that when disturbed, it will hyperinflate with water and releases an ink inside itself, quickly becoming a not-so-invisible opaque creature in the blink of an eye!

bigfin, reef, squid

A transparent squid (Photo credit: eye-blink/Shutterstock)

This impressive exchange of camouflage can be seen in both octopuses and squids, and is an adaptation that can keep several types of predators at bay. The top predators are those that lurk in the deep seas and perpetually gaze above them, hoping to catch any prey that shows the slightest hint of shadow. Second predators are those that spotlight their prey in “biological” headlights, aka bioluminescence.

By being able to go from invisible to opaque, octopuses and squids can fool both types of predators. Above all, they must make this exchange on time, because if they don’t, and the bioluminescent light hits their transparent selves, it would be like a flashlight shining on glass at night – reflective and very obvious to observers/predators.

One last word

If you thought finding Dory was difficult, wait until you see what her newly hatched baby would have looked like – almost invisible! Larval forms of Pacific blue tangs and Atlantic blue tangs are just over a millimeter long and transparent, much like surgeonfish and moray eel larvae.

Transparency may be much rarer on earth, but as always, there are exceptions. From Clearwing butterflies, whose clear wings allow them to blend in with the scenery, to glass frogs that allow us to look directly into their intestines, their bones and even their little beating hearts, terrestrial life also seems to have adapted techniques of effective camouflage using transparency.

Of all the superpowers enjoyed by the animal kingdom, the ability to turn invisible is one of the coolest!

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