Spawning Behavior

Mating Behavior
A stereotyped pattern of spawning behavior of Hynobius nigrescens (Hasumi, 1994).

(A) When a female (red) clings to part of a twig and rubs her cloacal opening on it, a male (green) brings his snout close to her cloacal opening.

(B) After the female attached the adhesive tips of a pair of egg sacs (light blue) to part of the twig, the male mounts on her back and folds his forelimbs around her pelvic region (amplexus).

(C) Immediately after the egg sacs begin to protrude from a female's cloaca, the male shifts his forelimbs to them.

(D) The male pushes the female away with his hindlimbs, discharging seminal fluid on the egg sacs. This action results in the egg sacs being freed from the female's cloaca (midwifing). At this time, 1-2 neighboring males rush to form a mating ball about the male-female-egg sac complex, and then some other males assemble and participate in the mating ball, apparently scramble-competing to fertilize the eggs.


Copyright 2002 Masato Hasumi, Dr. Sci. All rights reserved.
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