The life of all creatures are distilled into on great moment of supreme effort at the time of mating. It is the moment when a species matches the best males with the worthiest females. The DARWINIAN CONCEPT of the SURVIVAL OF THE FITTEST seems to be given form during the act of mating.
When the PARAMECIUM and HYMENA are mating, they release into the water chemicals that stimulate mating behavior among the same or related kinds of PROTOZOA.
FISHES: The male remain in the vicinity of his nest until a female swims near. On seeing her, he performs what has been called a ZIGZAG dance for he swims in a series of short curved rushes around her. If she is responsive, she curves her head and tail upwards. This signal to the male causes him to swim near end then down to his nest entrance; the female follows him. At the entrance the male nudes the opening with his nose and the female pushes past him to swim into the nest, remaining with head out of one side and tail the other. The male than pushes the side and her tail persistently, a signal which causes the female to release her eggs to the nest.
The croaking of FROGS brings the males and females together, though the male may not be sure which is a female's and which is a male's croaking. Only when he grasps another male does he learn his mistake. The gripped male grunts, and the sound is enough to dislodge the amorous hold of the other frog.