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How do tuatara reproduce without fully developed hemipenes?
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tuatara
The species is the sole living member of the reptile order Rhynchocephalia.
Tuatara do not possess fully developed hemipenes, which are the copulatory organs found in lizards and snakes. Instead, they reproduce through a process known as cloacal apposition.12
During the mating season, the male courts the female through body displays and movements. When the female is receptive and remains stationary, the male approaches her, steps over her back, and positions his cloaca as close as possible to the female's cloacal vent. By aligning these openings, the male is able to transmit sperm directly into the female's reproductive tract. This method of cloacal apposition is unique to the tuatara among living reptiles, as most other reptiles utilize either a penis or hemipenes for internal fertilization.12