Amphibians

1

• Amphibians
• Urodela (salamanders, newts)
• Terrestrial, aquatic 550 species
• Retain tails as adults (paedomorphic character)
• Fertilization usually internal
• Anura (frogs, toads)
• Terrestrial, aquatic 5400 species
• Possess tails as juveniles not in adults
• Fertilization usually external
• Apoda (caecilians)
• Terrestrial (mostly), aquatic 170 species
• Legless (secondary)
• Fertilization internal

2

• Reptiles
• Keratin scales
• Amniotic egg
• Testudines/Chelonii (turtles, tortoises)
• Terrestrial, aquatic 325 species (7 marine)
• Rhynchocephalia (tuataras)
• Terrestrial 2 species (New Zealand)
• Least specialized reptile (similarities to
  Amphibia)
• Caudal autotomy (similar to Squamata)
• Squamata (snakes, lizards)
• Terrestrial, aquatic 9000 species (621 marine)
• Sister group to Rhynchocephalia
• Crocodilia (alligators, crocodiles, caimans,
  gavials)
• Semi-aquatic 24 species (1 marine)
• More closely related to birds than to other
  reptiles

3
Amniotic Egg
Fig. 11-2
4

• Reptiles
• Secondarily marine
• Ectotherms and poikilotherms
• Sea Turtles
• Unable to retract head or legs into shell
  (keratin bone)
• Shell dorsal carapace ventral plastron
• Subcutaneous fat deposits light spongy bones
  (buoyancy)
• Legs modified as flippers for swimming, steering
  (rear)
• Seven species Mainly warm water
• Some migrate or may appear in temperate waters
• Can be submerged up to 3 hours

5
Fig. 11-4
6
Video
7

• Marine Reptiles
• Sea Turtles
• Mate offshore sperm storage up to 2-3 years
• Lay eggs on land at night
• Dig hole in sand and lay 80-150 eggs
• Incubation period two months
• Gender of hatchlings determined by incubation
  temperature (environmental sex determination)
• Warm (gt30 oC) ? Females
• Cool (lt30 oC) ? Males
• Females return to same beach to spawn every 1-3
  years may migrate gt2000 km
• DNA evidence that site fidelity spans generations
• Require 10 years to reach sexual maturity

Fig. 11-6
Fig. 11-7
8

• Marine Reptiles
• Marine Iguana
• One species Galápagos Islands
• Males colored more brightly than females
• Different populations (different coloration) on
  various islands
• Dark colors may aid rapid heat absorption after
  leaving water
• Herbivores Feed on algae
• Can dive to 15 m video
• Can hold breath for 30-60 minutes
• Eliminate salt with salt glands near nostrils
  nasal spraying
• Good swimmers
• Long, laterally flattened tail
• Territorial
• Males fight to establish territories
• Males maintain small harems
• Females dig nests in sand for eggs

Fig. 11-9
9

• Marine Reptiles
• Sea Snakes
• 65 species Mainly tropical (Indian, Pacific)
• Coral reefs, open ocean
• Adaptations to aquatic lifestyle
• Scales reduced or absent
• Nostrils higher on head vs. terrestrial snakes
  specialized valves that seal nostrils when
  submerged
• Bodies flattened laterally (3-4 feet long at
  maturity)
• Paddle-shaped tail video
• Huge lung (extends into tail) gas exchange
  across trachea skin
• Can dive to 150 m (typically 5 m) hold breath
  2 hours
• Eliminate salt via salt gland under tongue
• Ovoviviparous
• Gestation 4-11 months
• Few species lay eggs on shore
• Venomous
• Closely related to cobras
• Venom typically used to kill small prey (fishes,
  squids)