Slide 1 of 47 Copyright Pearson Prentice Hall Biology

Slide 2 of 47 Copyright Pearson Prentice Hall 30-3 Amphibians

Slide 3 of 47 Copyright Pearson Prentice Hall What Is an Amphibian? What is an amphibian?

30-3 Amphibians Slide 4 of 47 Copyright Pearson Prentice Hall What Is an Amphibian? An amphibian is a vertebrate that, with some exceptions: lives in water as a larva and on land as an adult breathes with lungs as an adult has moist skin that contains mucous glands lacks scales and claws

30-3 Amphibians Slide 5 of 47 Copyright Pearson Prentice Hall Evolution of Amphibians How are amphibians adapted for life on land?

30-3 Amphibians Slide 6 of 47 Copyright Pearson Prentice Hall Evolution of Amphibians The first amphibians appeared in the late Devonian Period, about 360 million years ago. The transition from water to land required that the terrestrial vertebrates had to: breathe air, protect themselves and their eggs from drying out, and support themselves against the pull of gravity.

30-3 Amphibians Slide 7 of 47 Copyright Pearson Prentice Hall Evolution of Amphibians Early amphibians evolved several adaptations that helped them live at least part of their lives out of water. Bones in the limbs and limb girdles of amphibians became stronger, permitting more efficient movement.

30-3 Amphibians Slide 8 of 47 Copyright Pearson Prentice Hall Evolution of Amphibians Lungs and breathing tubes enabled amphibians to breathe air. The sternum formed a bony shield to support and protect internal organs, especially the lungs.

30-3 Amphibians Slide 9 of 47 Copyright Pearson Prentice Hall Evolution of Amphibians Amphibian Adaptations Pelvic Girdle Lungs Leg Bones: The legs of a land vertebrate must be strong enough to hold its weight. Skin: The skin and the lining of the mouth cavity of many adult amphibians are thin and richly supplied with blood vessels. Watery mucus is secreted by glands in the skin.

30-3 Amphibians Slide 10 of 47 Copyright Pearson Prentice Hall Evolution of Amphibians In many adult amphibians, the internal surfaces of the lungs are richly supplied with blood vessels and folds that increase surface area. Lungs

30-3 Amphibians Slide 11 of 47 Copyright Pearson Prentice Hall Form and Function in Amphibians The class Amphibia is relatively small and diverse.

30-3 Amphibians Slide 12 of 47 Copyright Pearson Prentice Hall Form and Function in Amphibians Feeding Tadpoles are typically filter feeders or herbivores that graze on algae. Their intestines help break down hard-to-digest plant material and are usually filled with food. The feeding apparatus and digestive tract of adults are meat-eating structures.

30-3 Amphibians Slide 13 of 47 Copyright Pearson Prentice Hall Form and Function in Amphibians Frog Anatomy

30-3 Amphibians Slide 14 of 47 Copyright Pearson Prentice Hall Form and Function in Amphibians Adult amphibians are almost entirely carnivorous. Many salamanders and frogs have long, sticky tongues specialized to capture insects.

30-3 Amphibians Slide 15 of 47 Copyright Pearson Prentice Hall Form and Function in Amphibians In a frog’s digestive system, food slides down the esophagus into the stomach. Stomach Esophagus Mouth

30-3 Amphibians Slide 16 of 47 Copyright Pearson Prentice Hall Form and Function in Amphibians The breakdown of food begins in the stomach and continues in the small intestine. Stomach Small intestine

30-3 Amphibians Slide 17 of 47 Copyright Pearson Prentice Hall Form and Function in Amphibians The liver, pancreas, and gallbladder secrete substances that aid in digestion. Gallbladder Liver Pancreas

30-3 Amphibians Slide 18 of 47 Copyright Pearson Prentice Hall Form and Function in Amphibians At the end of the large intestine is a muscular cavity called the cloaca, through which digestive wastes, urine, and eggs or sperm leave the body. Cloaca Large intestine (colon)

30-3 Amphibians Slide 19 of 47 Copyright Pearson Prentice Hall Form and Function in Amphibians Respiration In most larval amphibians, gas exchange occurs through the skin and the gills. Adult amphibians typically respire using lungs, but some gas exchange occurs through the skin and the lining of the mouth.

30-3 Amphibians Slide 20 of 47 Copyright Pearson Prentice Hall Form and Function in Amphibians Circulation In frogs and other adult amphibians, the circulatory system forms a double loop. The first loop carries oxygen-poor blood from the heart to the lungs and skin, and takes oxygen-rich blood from the lungs and skin back to the heart.

30-3 Amphibians Slide 21 of 47 Copyright Pearson Prentice Hall Form and Function in Amphibians The second loop transports oxygen-rich blood from the heart to the rest of the body, and carries oxygen- poor blood from the body back to the heart.

30-3 Amphibians Slide 22 of 47 Copyright Pearson Prentice Hall Form and Function in Amphibians Amphibian Circulation and Excretion Heart Lung Kidney Ureter Cloaca Urinary bladder

30-3 Amphibians Slide 23 of 47 Copyright Pearson Prentice Hall Form and Function in Amphibians The amphibian heart has three separate chambers: left atrium right atrium ventricle

30-3 Amphibians Slide 24 of 47 Copyright Pearson Prentice Hall Form and Function in Amphibians Amphibian Heart Right atrium Left atrium Ventricle From Body To body, lungs and skin From Lungs

30-3 Amphibians Slide 25 of 47 Copyright Pearson Prentice Hall Form and Function in Amphibians Excretion Amphibians have kidneys that filter wastes from the blood. Urine travels through tubes called ureters into the cloaca. Urine is then passed directly to the outside, or temporarily stored in a small urinary bladder just above the cloaca.

30-3 Amphibians Slide 26 of 47 Copyright Pearson Prentice Hall Form and Function in Amphibians Reproduction In most species of amphibians, the female lays eggs in water, then the male fertilizes them externally. In a few species, including most salamanders, eggs are fertilized internally. After fertilization, frog eggs are encased in a sticky, transparent jelly.

30-3 Amphibians Slide 27 of 47 Copyright Pearson Prentice Hall Form and Function in Amphibians The jelly attaches the egg mass to underwater plants and makes the eggs difficult for predators to grasp. The yolks of the eggs nourish the embryos. Most amphibians abandon their eggs after they lay them. A few amphibians take care of both eggs and young.

30-3 Amphibians Slide 28 of 47 Copyright Pearson Prentice Hall Form and Function in Amphibians Frog Metamorphosis Adult Frog Young Frog Fertilized eggs Tadpoles

30-3 Amphibians Slide 29 of 47 Copyright Pearson Prentice Hall Form and Function in Amphibians Adults are typically ready to breed in about one to two years. Frog eggs are laid in water and undergo external fertilization.

30-3 Amphibians Slide 30 of 47 Copyright Pearson Prentice Hall Form and Function in Amphibians The fertilized eggs hatch into tadpoles a few days to several weeks later. Fertilized eggs

30-3 Amphibians Slide 31 of 47 Copyright Pearson Prentice Hall Form and Function in Amphibians Tadpoles gradually grow limbs, lose their tails and gills, and become meat-eaters as they develop into terrestrial adults. Young frog Tadpole

30-3 Amphibians Slide 32 of 47 Copyright Pearson Prentice Hall Form and Function in Amphibians Movement Amphibian larvae move by wiggling their bodies and using a flattened tail for propulsion. Adult salamanders walk or run. Frogs and toads, have well-developed hind limbs that enable them to jump long distances.

30-3 Amphibians Slide 33 of 47 Copyright Pearson Prentice Hall Form and Function in Amphibians Response Amphibians have well-developed nervous and sensory systems. An amphibian's eyes are protected from damage and kept moist by a transparent nictitating membrane. This membrane is located inside the regular eyelid and can be closed over the eye.

30-3 Amphibians Slide 34 of 47 Copyright Pearson Prentice Hall Form and Function in Amphibians Amphibians hear through tympanic membranes, or eardrums, located on each side of the head. Many amphibian larvae and adults have lateral line systems that detect water movement.

30-3 Amphibians Slide 35 of 47 Copyright Pearson Prentice Hall Form and Function in Amphibians Frog’s Sense Organs

30-3 Amphibians Slide 36 of 47 Copyright Pearson Prentice Hall Groups of Amphibians What are the main groups of living amphibians?

30-3 Amphibians Slide 37 of 47 Copyright Pearson Prentice Hall Groups of Amphibians The three groups of amphibians alive today are: salamanders frogs and toads caecilians

30-3 Amphibians Slide 38 of 47 Copyright Pearson Prentice Hall Groups of Amphibians Salamanders Salamanders and newts have long bodies and tails. Most have four legs. Both adults and larvae are carnivores. Adults usually live in moist woods, where they tunnel under rocks and rotting logs.

30-3 Amphibians Slide 39 of 47 Copyright Pearson Prentice Hall Groups of Amphibians Frogs and Toads Frogs and toads have the ability to jump. Frogs tend to have long legs and make lengthy jumps. Toads have relatively short legs and are limited to short hops.

30-3 Amphibians Slide 40 of 47 Copyright Pearson Prentice Hall Groups of Amphibians Frogs are generally more closely tied to water than toads. Toads often live in moist woods and even in deserts.

30-3 Amphibians Slide 41 of 47 Copyright Pearson Prentice Hall Groups of Amphibians Caecilians Caecilians are legless animals that live in water or burrow in moist soil or sediment. Caecilians feed on small invertebrates such as termites. Many have fishlike scales embedded in their skin.

- or - Continue to: Click to Launch: Slide 42 of 47 Copyright Pearson Prentice Hall 30-3

Slide 43 of 47 Copyright Pearson Prentice Hall 30-3 The word amphibian refers to the ability to a.live in hot climates. b.live in wet places. c.live both in water and on land. d.live in cold and hot climates.

Slide 44 of 47 Copyright Pearson Prentice Hall 30-3 Fossil evidence indicates the first land amphibians appeared during the a.Jurassic Period. b.Devonian Period. c.Cambrian Era. d.Cretaceous Era.

Slide 45 of 47 Copyright Pearson Prentice Hall 30-3 In a larval amphibian, gas exchange occurs through a.the skin only. b.both the skin and the gills. c.the gills only. d.a lung.

Slide 46 of 47 Copyright Pearson Prentice Hall 30-3 The tympanic membrane in a frog enables it to a.hear. b.see. c.smell. d.taste.

Slide 47 of 47 Copyright Pearson Prentice Hall 30-3 Which of the following is a group of amphibians living on the Earth today? a.crocodiles b.snakes c.salamanders d.lizards

END OF SECTION