Harlequin rasbora of a harlequin. The harlequin rasbora is a fish that has an approximately lozenge-shaped body, whose basal colour from the head to the caudal peduncle is an orange-pink, the exact hue varying depending upon such factors as water conditions and the original population from which the fish was obtained. The posterior half of the body is overlaid with a large, roughly triangular black marking, that tapers toward the terminal end of the caudal peduncle, and begins approximately below the midpoint of the attachment of the dorsal fin (commonly called a "black wedge"). In common with all cyprinids, the articulation of
Caudal luring often in juvenile snakes and is most prevalent in vipers and pitvipers, but it also occurs in boas, pythons, tropidophiids, colubrids, and elapids of the genus Acanthophis. Caudal luring has been used as an experimental paradigm to investigate stimulus control and visual perception in viperid snakes. It has been suggested that caudal luring was involved in the evolution of the rattlesnake rattle. Attempts have been made to test this hypothesis, however, the evidence is contentious. There have been dubious reports of caudal luring and concomitant speculations. Prey luring in general is confounded by false interpretation. The difficulty is that there