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Amphibians

Amphibians. Section 30.2. Animal Classification. Sponges Cnidarians Worms Mollusks Arthropods Echinoderms. Order Anura Order Caudata Order Apoda. Invertebrates. Animals. Fishes Amphibians Reptiles. Ectotherms (cold-blooded). Amphibians. Vertebrates. Phylum Chordata. Birds

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Amphibians

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  1. Amphibians Section 30.2

  2. Animal Classification Sponges Cnidarians Worms Mollusks Arthropods Echinoderms • Order Anura • Order Caudata • Order Apoda Invertebrates Animals Fishes Amphibians Reptiles Ectotherms (cold-blooded) Amphibians Vertebrates Phylum Chordata Birds Mammals Endotherms (warm-blooded)

  3. What is an Amphibian? • Class Amphibia – means “double life” • Starts life in water and changes on land • Evolutionary advantages over fishes • Thin, moist skin • Most amphibians have four legs • Lungs

  4. What is an Amphibian? • Nearly all amphibians rely on water for reproduction • Undergo external fertilization • Water is needed to transport sperm

  5. Ectotherms • Ectotherm – an animal that has a variable body temperature and gets its heat from external sources (can’t regulate their body temperature on their own)

  6. Ectotherms • Amphibians become dormant in regions that are too hot or cold for part of the year • Many of them burrow into mud and stay there until suitable conditions return

  7. Metamorphosis • Tadpoles possess fins, gills, and a two-chambered heart as seen in fish • Tadpoles develop legs, lungs, and a three-chambered heart to become adults

  8. Metamorphosis • Young salamanders resemble adults, and they have gills and usually have a tail fin • Most adult salamanders lack gills and fins • Adult salamanders have no lungs and breathe only through their skin

  9. Walking Requires More Energy • The evolution of the three-chambered heart in amphibians ensured that cells received the proper amount of oxygen

  10. Walking Requires More Energy • One atrium receives oxygen-rich blood from the lungs and skin • Another atrium receives oxygen-poor blood from the body tissues • Blood from both chambers then moves to the third chamber (or ventricle) which mixes the two types of blood

  11. Walking Requires More Energy • Because of the mixture of blood, the skin is much more important than the lungs as an organ for gas exchange

  12. Walking Requires More Energy • Because the skin of an amphibian must stay moist to exchange gases, most amphibians are limited to life on the water’s edge or other moist areas

  13. Frogs and Toads • Frogs and toads belong to the order Anura • Frogs have long hind legs and smooth, moist skin • Toads have short legs and bumpy, thick, dry skin

  14. Frogs and Toads • Adult frogs and toads are predators that eat invertebrates, such as insects and worms • Many species of frogs and toads secrete chemicals through their skin as a defense against predators Frog eating bird

  15. Frogs and Toads • Frogs and toads also have vocal cords • Vocal cords – sound-producing bands of tissue in the throat • As air moves over the vocal cords, they vibrate and cause molecules in the air to vibrate

  16. Frogs and Toads • Tympanic membrane – used for hearing; amplifies sounds frogs and toads make • Throat pouches and tympanic membranes increase the loudness of their calls

  17. Frogs and Toads • Frogs and toads are among the first organisms to be exposed to pollutants in the air, on land, or in the water • Declining numbers of frogs species sometimes indicate the presence of pollutants in the environment

  18. Salamanders • A salamander (order Caudata) has a long, slender body with a neck and tail • Salamanders resemble lizards, but have smooth, moist skin and lack claws

  19. Salamanders • The young hatch from eggs, look like small salamander adults, and are carnivorous

  20. Caecilians • Caecilians (order Apoda) are burrowing amphibians, have no limbs, and have a short (or no) tail • They are tropical animals with small eyes that often are blind

  21. Caecilians • They eat earthworms and other invertebrates found in the soil • All caecilians have internal fertilization

  22. Challenges of Life on Land • Some dangers living on land • 1. Temperature of water remain fairly constant while air temperatures can vary greatly

  23. Challenges of Life on Land • 2. Without the support of water, the body was clumsy and heavy • The legs of a salamander are set at right angles to the body. This prevent the belly from dragging on the ground.

  24. Challenges of Life on Land • Raised trunks from the ground increases mobility

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