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

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Presentation on theme: "I. I.Amphibians A. A.Urodela (salamanders, newts) Terrestrial, aquatic: ~550 species Retain tails as adults (paedomorphic character) Fertilization usually."— Presentation transcript:

1 I. I.Amphibians A. A.Urodela (salamanders, newts) Terrestrial, aquatic: ~550 species Retain tails as adults (paedomorphic character) Fertilization usually internal B. B.Anura (frogs, toads) Terrestrial, aquatic: ~5400 species Possess tails as juveniles; not in adults Fertilization usually external C. C.Apoda (caecilians) Terrestrial (mostly), aquatic: ~170 species Legless (secondary) Fertilization internal

2 II. II.Reptiles Keratin scales Amniotic egg A. A.Testudines/Chelonii (turtles, tortoises) Terrestrial, aquatic: ~325 species (7 marine) B. B.Rhynchocephalia (tuataras) Terrestrial; 2 species (New Zealand) Least specialized reptile (similarities to Amphibia) Caudal autotomy (similar to Squamata) C. C.Squamata (snakes, lizards) Terrestrial, aquatic; ~9000 species (62+1 marine) Sister group to Rhynchocephalia D. D.Crocodilia (alligators, crocodiles, caimans, gavials) Semi-aquatic; 24 species (1 marine) More closely related to birds than to other reptiles

3 Fig Amniotic Egg

4 II. II.Reptiles Secondarily marine Ectotherms and poikilotherms A. A.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 III. III.Marine Reptiles A. A.Sea Turtles Mate offshore; sperm storage up to 2-3 years Lay eggs on land at night Dig hole in sand and lay eggs Incubation period ~ two months Gender of hatchlings determined by incubation temperature (environmental sex determination) Warm (>30 o C)  Females Cool (<30 o C)  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 Fig. 11-7

8 III. III.Marine Reptiles B. 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 videovideo Can hold breath for minutes Eliminate salt with salt glands near nostrils; nasal sprayingnasal 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 III. III.Marine Reptiles C. 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 videovideo 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)


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