Reptile Behavior and Reproduction

Amniotic Egg

• allows a protected, aquatic environment where young can develop on land » increased survival and reproduction

• Except for crocodilians, shell is leathery

• 4 extraembryonic membrances

  • chorion—gas exchange

  • amnion—fluid filled for protection

  • yolk sac—contains the yolk, which provides nutrition

  • allantois—waste repository

Timing of reptile reproduction

• temperature—most important

• photoperiod—smaller role

• breed about 4-8 weeks after coming out of brumation

• usually one clutch of eggs

Mate selection

• smell—some species secrete pheromones to attract mates—ex) musk turtles

• Vision—displays—ex) anoles’ throat fan (dewlap), head bobbing turtles

• some use a combination of smell and sight cutes

Multiple matings

• increase genetic diversity

• sperm from different individuals compete inside one female

• females “choose” against those genetically related

Ovipary and Vivipary

• Most lay eggs—oviparous

• Some give live birth—ovoviviparous

  • Viperidae

  • Some Scinidae

  • Thmanophis

Parthenogenesis

• Asexual reproduction—new individual develops from unfertilizated egg

  • most common in lizards

  • accounts in timber rattlesnake, garter snake

  • some species only use parthenogenesis, some do it faculatively

Eggs, incubation, and hatching

• Many species retain eggs inside body until halfway through development, some until almost hatched

• Embryonic development—5 weeks to 16 weeks for turtles, lizards, and snakes

• Sex determined by incubation temperature middle third of incubation

• Incubation temp can have affect on long term survival, growth rate, behavior

• Caruncle—egg tooth used to crack the shell, reabsorbed after birth

Parental Care and Development

• Many lizards and snakes care for eggs, but very few care for young

• Reptiles are completely developed upon hatching

  • capable of feeding, moving, and defending themselves

  • Reptiles continue to grow through their life

    • size, not age, determines sexual maturity