Chelonian Reproduction - Anatomy & Physiology

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Anatomy of the Male Chelonian

© L.Wilkie 2008


  • Long, yellow and oval in shape.
  • Attached to the cranioventral pole of the kidneys.
  • Ductus deferens runs alongside ureters to the cloaca.


  • Ventral proctodeum is modified and thickened into a single phallus.
  • Two pairs of fibrous tissue separated by a central trough.
  • Cannot be inverted (unlike lizards and snakes).
  • Highly vascular.
  • When inserted into the female cloaca it becomes engorged.
  • Semen is conveyed through the central sulcus.
  • A retractor muscle returns the phallus back into the cloaca.



  • Paired ovaries lie symmetrically, cranial to the kidneys.
  • Irregular, sac-like.
  • Different sized ova that become prominent with mature follicles.

Sperm Storage in the Female Tract

  • Females in some species can retain sperm in their uterus.
  • Can successfully fertilize two or more clutches, often several years after copulation.

The Egg

All chelonians are oviparous.

Temperate Species

  • Lay eggs with soft, flexible, leathery shells.
  • Can absorb and loose moisture.
  • Develop more rapidly.
    • Incubation ~2 months.

Tropical Species and Land Tortoises

  • Lay eggs with a hard, brittle shell.
  • Prevents eater loss.
  • Develop less rapidly.
    • Incubation ~8-9 months.

  • Egg hatching depends on climate conditions such as spring warmth and seasonal rains.


  • Courtship and mating is very vocal.
    • Crying, grunting and barking
  • Male mounts from the rear.
  • Internal fertilization