Frogfish (family Antennariidae)

I was convinced I had to blog about these fish as soon as I saw their name. It immediately conjured images of strange frog-fish hybrids, which of course would never happen. It turns out that the name frogfish is one of the least interesting things about these guys. Frogfish are actually anglerfish, and make up the family Antennariidae.

Frogfish are found pretty much anywhere in tropical or subtropical waters, in both oceans and seas. The most dense area of frogfish species is around Indonesia, where nine different species were found in a single strait. Frogfish like to live in and around coral reefs, and rarely stray deeper than 100 m.

Describing frogfish as a group is fairly difficult, because they are so varied in appearance. They are generally stout, looking more like irregular round balls than fish. They range in size from 2.5 to 38 cm long. Many species are covered in spinules, which can take the form of bumps or spine-like projections. Colours in frogfish can differ both between and within species, and can include white, yellow, red, green, and black.

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A well-disguised frogfish. You can barely even tell that this is an animal. Image credit: Stephen Childs via Wikipedia

Frogfish are so different in appearance because they are masters of camouflage. These fish don’t have scales or any other form of protection, so they rely on their disguises to keep them safe from predators. Frogfish successfully imitate coral and stones, sponges, sea urchins, and seaweed. Sea slugs have been so fooled by frogfish camouflage that they have crawled on them, completely unaware that they were actually moving on top of living fish.

Another excellently disguised part of frogfish is their escas, or lures. These can take the form of a number of different ‘creatures’, including fish, shrimp, and worms. Frogfish use the lures to entice prey into approaching to a fatal distance. They hunt a variety of prey, such as crustaceans, fish, and other frogfish. Frogfish can expand their stomachs, allowing them to eat animals twice their size. Frogfish will wave their lures around, mimicking the movements of the animal the lure is disguised as. When the prey gets close enough, the frogfish open their jaws in a rapid motion, which sucks the prey inside. This action occurs extremely quickly, in as little six milliseconds.

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A crazy-looking frogfish with a nice fat worm as a lure. Image credit: Jens Petersen via Wikipedia

This is about the only movement frogfish do quickly. The rest of the time, they walk ponderously across the ocean floor, if they move at all. Though frogfish can swim, they prefer to walk along the ocean floor, either in an ambling walk or a kind of gallop. If given a choice, however, they would choose not to move, and lie still waiting for prey to approach.

Though I’ve written about a number of camouflage experts, I think frogfish are probably some of the best around. It’s a shame they aren’t actually a cross between frogs and fish though, like I initially thought. They’re still super cool though!

Cover image credit: Tanaka Juuyou via Wikipedia

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