To turn invisible, we need to tweak the path light travels

That’s what makes Invisible Woman an invaluable member of the Fantastic Four. She can disappear in the blink of an eye and take out entire factions of enemies, all while her adversaries kick and punch empty air. Characters with invisibility powers — Marvel Comics’ Invisible Woman (aka Sue Storm), H.G.

Wells’ Invisible Man and The Incredibles’ Violet Parr — can do all sorts of cool things. Escape embarrassing situations. Go places where they’re not allowed.

Short of a theoretical invisibility cloak, that kind of lurking is impossible for us. But some animals can hide in plain sight by turning nearly transparent. Invisibility is useful for animals that spend a lot of time in places with no good hiding spots, such as the air or open ocean, says Kate Feller, a visual ecologist at Union College in Schenectady, N.Y.

The secret to invisibility is all about light. The more light that can pass through something undisturbed, the harder it is to see that thing. Light can’t easily pass through most animals, but those with nearly invisible body parts have tricks to get around this hurdle.

Animals get their colors from pigments, compounds that appear as different colors depending on which wavelengths of light they absorb and which they reflect. Green pigments, for instance, reflect green light and absorb all other colors. Invisibility requires getting rid of these colorful compounds.

Most baby fish lack pigments at first, helping them hide from predators. Some species stay see-through their whole lives. One is the ghost catfish (Kryptopterus vitreolus).