About Rhycherus filamentosus (Castelnau, 1872)
This species is a frogfish, and frogfish in its family have compressed, globose bodies, laterally positioned eyes, and large, obliquely slanting mouths. The first dorsal spine of these fish is modified into an elongated, slender illicium, tipped with an esca—a whitish, worm-like lure. Rhycherus filamentosus can reach a total length of approximately 23 cm (9 in). Its skin is abundantly covered in threads and filaments that resemble fronds of red algae. This well-camouflaged fish has a base colour of reddish-brown, marked with vertical bars and patches of dark and pale brown, and has whitish underparts. Rhycherus filamentosus is endemic to Australia, where it occurs in the southeastern Indian Ocean and the southwestern Pacific Ocean. Its range stretches from Spencer Gulf in South Australia at 130°E to the eastern end of the Bass Strait at 149°E. It is associated with reefs and can be found at depths down to around 60 m (200 ft). Rhycherus filamentosus is a benthic fish that lives on the seabed and rarely swims; instead, it moves across the seabed using its pectoral and pelvic fins in a walking motion. It is a well-camouflaged ambush predator: it rests on the seabed, and waggles its esca when potential prey approaches. When the prey draws closer, the fish positions itself, then strikes with great speed by opening its mouth and sucking the prey in.
