The tail skeleton of the guppy P. reticulata. The first (1) and last (15) tail vertebrae, shown in an adult female. Cartilage that fixes the last three tail vertebrae to the caudal complex is stained with Alcian blue (arrow). Insert shows the haemal spines of first two vertebrae of an adult male that are transformed into the suspensorium for the gonopodium (g). Scale bar is 1 mm.