It carries a false eye at the back of the body, and that is what it is named for.
A dark round spot ringed with pale sits at the base of the soft dorsal fin, near the rear end of the fish, in exactly the place where an eye is not. It is a common trick on reef fish and it does two things. A predator that strikes at what it takes to be the head hits the tail end and gets a mouthful of fin instead of anything vital, while the fish leaves in the opposite direction to the one expected. And a predator deciding whether to attack at all reads the spot as a much larger animal facing it, because a big eye implies a big head.
On a frogfish there is a third use. This is an animal whose entire living depends on not being recognized as a fish, and a conspicuous round mark helps break up the outline of a shape that is otherwise suspiciously fish-sized, the same way a bold blotch on a sponge does.
Underneath it is a small ambush hunter, up to thirteen centimeters, in pink, orange, brown or dull red, sitting motionless on rubble and sponge and fishing with a lure it keeps folded away until something worth catching comes past.
- large dark round spot at the base of the soft dorsal fin, ringed and eye-like
- small, up to 13 cm, in pink, orange, brown or dull red
- lure on a short rod, held folded until it is used
- up to 13 cm
Why it's threatened
Antennatus nummifer is utilized by the aquarium trade (Pietsch and Grobecker 1987).
Threat classification from the IUCN Red List.
