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Camouflage is a way to mislead the sense organs like eyes, nose or tongue into perceiving something different. Most animals use camouflage to hide from possible predators (= protective resemblance). In contrast the frogfish signals to other animals, that it is a place of shelter (rock, sponge) or a grazing ground (if is looks like algae). Having perceived the frogfish as nothing threatening, these animals approach and then get eaten. This is called aggressive resemblance.
The frogfish is a master of camouflage. His body is often covered with spots, stripes, warts, skin flaps and filaments. The frogfish mimics substrate and structures like algae covered rocks or rubble, plants like sargassum weed or algae, and animals like tunicates, corals and sponges. For example the striped frogfish (A. striatus) looks with the help of skin flaps and appendages just like the algae it is hiding in. Other frogfishes look like sponges, down to the openings they immitate with spots on their skin.
Changing Colors
Because of their camouflage frogfish are difficult to find and - because they asume various colors - even more difficult to identify. Individuals of the same species can look to us completely different. To compound the problem most frogfishes can change their color in a matter of days or weeks. They mimic some objects in their immediate vicinity such as sponges, rocks, corals, tunicates. If they move to darker surroundings their body will adapt and change to a darker color. You often find black frogfishes on black sponges or close to black tunicates and yellow frogfishes inside yellow sponges and the patterns on frogfish skin often resemble the openings (ostia) of sponges or the apertures of sea squirts. The aggressive mimicry and the feeding behavior of frogfishes is one of natures most highly evolved example of "lie-in-wait" predation.
Locomotion
Frogfish don't swim very often, most of them lack a swim bladder (except the sargassum frogfish Histrio histrio). To cross small distances the frogfish may walk or actually gallop (see illustration). It can also move very quickly by sucking in large quantities of water through the mouth and forcing it out through the tiny gill openings. This results in a jet-like very fast forward propulsion a few centimeters above the ground.
It is interesting to note that frogfishes have reversed the order of their breast fins and belly fins. The powerful rear feet are in fact its breast fins!
Credits to Copyright Teresa Zubi
