I. Amphibians

A. Urodela (salamanders, newts)• Terrestrial, aquatic: ~550 species• Retain tails as adults (paedomorphic character)• Fertilization usually internal

B. Anura (frogs, toads)• Terrestrial, aquatic: ~5400 species• Possess tails as juveniles; not in adults• Fertilization usually external

C. Apoda (caecilians)• Terrestrial (mostly), aquatic: ~170 species• Legless (secondary)• Fertilization internal

II. Reptiles

• Keratin scales• Amniotic eggA. Testudines/Chelonii (turtles, tortoises)

• Terrestrial, aquatic: ~325 species (7 marine)

B. Rhynchocephalia (tuataras)• Terrestrial; 2 species (New Zealand)• Least specialized reptile (similarities to Amphibia)• Caudal autotomy (similar to Squamata)

C. Squamata (snakes, lizards)• Terrestrial, aquatic; ~9000 species (62+1 marine)• Sister group to Rhynchocephalia

D. Crocodilia (alligators, crocodiles, caimans, gavials)• Semi-aquatic; 24 species (1 marine)• More closely related to birds than to other reptiles

Fig. 11-2

Amniotic Egg

II. Reptiles

• Secondarily marine• Ectotherms and poikilothermsA. 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

Fig. 11-4

Video

III. Marine Reptiles

A. 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

III. Marine Reptiles

B. 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

III. Marine Reptiles

C. 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)