Presentation Transcript

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 (62+1 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 (>30 oC)  Females • Cool (<30 oC)  Males • Females return to same beach to spawn every 1-3 years; may migrate >2000 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) • May hunt in schools • Some actively trap prey; others lie in wait • Few natural predators (seabirds, sharks, saltwater crocodiles)