Cordyceps: attack of the killer fungi - Planet Earth Attenborough BBC wildlife. Transformer Owl. Penis fencing. Two individuals of Pseudobiceros bedfordi preparing for penis fencing.
P. bedfordi is exceptional in that it applies sperm onto the partner's skin rather than injecting it. Penis fencing is a mating behavior engaged in by certain species of flatworm, such as Pseudobiceros hancockanus. Species which engage in the practice are hermaphroditic; each individual has both egg-producing ovaries and sperm-producing testes.[1] The flatworms "fence" using two-headed dagger-like penises which are pointed, and white in color. The mating ritual involves a violent battle during which two hermaphroditic flatworms attempt to pierce the skin of one another with one of their penises.