Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall
Biology Chapter 25 - Early Tetrapods and Amphibians Copyright Pearson Prentice Hall

Amphibians - first land animals
Animals that have gills and lungs during their life cycle… “transition animals” - From Water to Land Movement from water to land is perhaps the most dramatic event in animal evolution Photo Credit: Animals Animals/©Bill Beatty Copyright Pearson Prentice Hall

Ch. 25- Amphibians What Is an Amphibian? 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 gills as young and lungs as an adult has moist skin that contains mucous glands lacks scales and claws Copyright Pearson Prentice Hall

Evolution of Amphibians
Ch. 25- Amphibians Evolution of Amphibians How are amphibians adapted for life on land? How have they evolved? Copyright Pearson Prentice Hall

Ch. 25- Amphibians Evolution of Amphibians Lobe-finned fishes (lungfish) are the sister group to tetrapods Differences in the Tetrapods: Have stronger backbone Muscles to support the body in air Muscles to elevate the head Stronger shoulder and hip girdles More protective rib cage Modified ear structure to detect airborne sounds Foreshortening of skull Copyright Pearson Prentice Hall

Ch. 25- Amphibians Evolution of Amphibians Evolution of Amphibians The first amphibians appeared 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 support themselves against the pull of gravity Vascular plants, pulmonate snails, and tracheate arthropods made transition earlier Amphibians only living vertebrates that have a transition from water to land in their development Copyright Pearson Prentice Hall

Ch. 25- Amphibians Evolution of Amphibians Showing evolutionary link to fossil record. “Missing Link” organism from water (fish) to land (tetrapods). Copyright Pearson Prentice Hall

Ch. 25- Amphibians 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. Copyright Pearson Prentice Hall

Ch. 25- Amphibians Evolution of Amphibians Amphibian Adaptations Lungs Pelvic Girdle Leg Bones: The legs of a land vertebrate must be strong enough to hold its weight. The characteristics of amphibians include adaptations for living partially on land. For example, lungs enable adult amphibians to obtain oxygen from air. 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. Copyright Pearson Prentice Hall

Ch. 25- Amphibians 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. The characteristics of amphibians include adaptations for living partially on land. For example, lungs enable adult amphibians to obtain oxygen from air. Lungs Copyright Pearson Prentice Hall

Form and Function in Amphibians
Ch. 25- Amphibians Form and Function in Amphibians Form and Function in Amphibians The class Amphibia is relatively small and diverse. Copyright Pearson Prentice Hall

Ch. 25- Amphibians 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. Copyright Pearson Prentice Hall

Ch. 25- Amphibians Form and Function in Amphibians Frog Anatomy This illustration shows the organs of a frog’s digestive system. Copyright Pearson Prentice Hall

Ch. 25- Amphibians Form and Function in Amphibians Adult amphibians are almost entirely carnivorous. Many salamanders and frogs have long, sticky tongues specialized to capture insects. Copyright Pearson Prentice Hall

Ch. 25- Amphibians Form and Function in Amphibians Mouth Esophagus In a frog’s digestive system, food slides down the esophagus into the stomach. Stomach This illustration shows the organs of a frog’s digestive system. Copyright Pearson Prentice Hall

Ch. 25- Amphibians Form and Function in Amphibians The breakdown of food begins in the stomach and continues in the small intestine. Stomach Small intestine This illustration shows the organs of a frog’s digestive system. Copyright Pearson Prentice Hall

Ch. 25- Amphibians Form and Function in Amphibians The liver, pancreas, and gallbladder secrete substances that aid in digestion. Gallbladder Liver Pancreas This illustration shows the organs of a frog’s digestive system. Copyright Pearson Prentice Hall

Ch. 25- Amphibians 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. Large intestine (colon) Cloaca This illustration shows the organs of a frog’s digestive system. Copyright Pearson Prentice Hall

Ch. 25- Amphibians 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. SKIN: Thin skin loses water rapidly Restricts terrestrial forms to moist habitats Ectotherms Body temperature depends on environment and restricts range Copyright Pearson Prentice Hall

Ch. 25- Amphibians 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. 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. Copyright Pearson Prentice Hall

Ch. 25- Amphibians Form and Function in Amphibians The amphibian heart has three separate chambers: left atrium right atrium ventricle Copyright Pearson Prentice Hall

Ch. 25- Amphibians Form and Function in Amphibians To body, lungs and skin To body, lungs and skin Amphibian Heart From Body From Lungs Left atrium Right atrium Like all vertebrates, amphibians have a circulatory system and an excretory system. An amphibian’s heart has three chambers—two atria and one ventricle. Ventricle Copyright Pearson Prentice Hall

Ch. 25- Amphibians 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. Copyright Pearson Prentice Hall

Ch. 25- Amphibians Form and Function in Amphibians Reproduction - at age 1 or 2 years 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 using spermatophore. After fertilization, frog eggs are encased in a sticky, transparent jelly. Copyright Pearson Prentice Hall

Ch. 25- Amphibians 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. (Oviparous) Most amphibians abandon their eggs after they lay them. A few amphibians take care of both eggs and young. Copyright Pearson Prentice Hall

Ch. 25- Amphibians Form and Function in Amphibians Frog Metamorphosis Age 1 or 2 years Adult Frog Carnivores Fertilized eggs Young Frog Lose tails and gills An amphibian typically begins its life in the water, then moves onto land as an adult. This diagram shows the process of metamorphosis in a frog. Few days to several weeks Tadpoles Herbivores Copyright Pearson Prentice Hall

Ch. 25- Amphibians 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. Pupils: Do they constrict? Copyright Pearson Prentice Hall

Ch. 25- Amphibians 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. Copyright Pearson Prentice Hall

Ch. 25- Amphibians Form and Function in Amphibians Frog’s Sense Organs Photo Credit: Animals Animals/©Bill Beatty. A frog’s eyes and ears are among its most important sensory organs. Transparent eyelids called nictitating membranes protect the eyes underwater and keep them moist in air. Tympanic membranes receive sound vibrations from air as well as water. Copyright Pearson Prentice Hall

Ch. 25- Amphibians Groups of Amphibians What are the main groups of living amphibians? Copyright Pearson Prentice Hall

Ch. 25- Amphibians Groups of Amphibians Groups of Amphibians The three groups of amphibians alive today are: Salamanders: Order Urodela - tail evident (Order Caudata) frogs and toads: Order Anura - without tail (Order Salientia) Caecilians: Order Apoda - (aka: - naked snake) Copyright Pearson Prentice Hall

Ch. 25- Amphibians Groups of Amphibians Salamanders - Order Caudata (Urodela) Salamanders and newts have long bodies and tails. Most have four right angles to body. Respiration can occur through salamander skin, and lungs Both adults and larvae are carnivores. Adults usually live in moist woods, where they tunnel under rocks and rotting logs. Internal Fertilization: Female recovers in cloaca a spermatophore deposited on a leaf or stick Copyright Pearson Prentice Hall

Ch. 25- Amphibians Groups of Amphibians Copyright Pearson Prentice Hall

Ch. 25- Amphibians Groups of Amphibians Larval Salamander Red-Spotted Newt: Aquatic larva metamorphoses into red-eft, which remains on land for 1-3 years, until becoming secondary aquatic adult. A newt is a small salamander Copyright Pearson Prentice Hall

Ch. 25- Amphibians Groups of Amphibians Salamanders and Paedomorphosis Descendants retain into adulthood features that were present in larval stages of ancestors 2 species of salamanders that exhibit paedomorphosis. They both have their gills during their life cycle. Copyright Pearson Prentice Hall

Ch. 25- Amphibians Groups of Amphibians Frogs and Toads - Order Anura (Salientia) All have a tailed larval stage and tailless, jumping adults (except for 1 species - Ascaphus) Frogs and toads have the ability to jump. Toads have thicker skin, covered in “warty” projection glands that secrete poison. The poison is only harmful if swallowed or gets in your eyes. Must live near water source Reproduction mode requires water Skin is water-permeable skin Coastal Tailed Frog Copyright Pearson Prentice Hall

Ch. 25- Amphibians Groups of Amphibians Tree Frog Frogs 44 families of frogs and toads Family Ranidae common larger frogs in North America Family Hylidae Includes the tree frogs Family Bufonidae (toads) Contains toads with thicker skins and prominent warts Conraua goliath- Largest frog Toad Copyright Pearson Prentice Hall

Ch. 25- Amphibians Groups of Amphibians African Clawed Frog - has been introduced to California in 1940 (researchers used frog in Pregnancy tests) , and is now a huge pest. Aggressive and has caused a decline in native frogs. Similar to when huge toads were introduced to Australia. Copyright Pearson Prentice Hall

Ch. 25- Amphibians Groups of Amphibians Epidermis has two types of integumentary glands Mucous glands secrete protective waterproofing Large serous glands produce a whitish, watery poison Dendrobatid frogs of South America secrete highly toxic skin poisons Copyright Pearson Prentice Hall

Ch. 25- Amphibians Groups of Amphibians Skeleton of frog: notice human similarities and differences. Feet - 5 digits, hand - 4 digits Copyright Pearson Prentice Hall

Ch. 25- Amphibians Groups of Amphibians Respiration in frogs: No diaphragm to help, instead use pressure within cavities. Force mouth down, air moves into mouth thru nostrils Force mouth up, air forced into lungs Mouth ventilates Muscles in abdominal wall and recoiling of lungs forces air out. Most Carbon Dioxide is lost through the skin, not lungs. Vocal cord more developed in males. Copyright Pearson Prentice Hall

Ch. 25- Amphibians Groups of Amphibians Caecilians - Order Apoda Caecilians are legless animals that live in water or burrow in moist soil or sediment. Most species are blind Caecilians feed on small invertebrates such as termites. Found in S.America, Africa, India (Up to 1.5 M) Have vertebrae, skull, and long ribs. Internal Fertilization (some have copulatory organ) Most Oviparous, although some viviparous (young feed on walls of oviduct). Larva - some aquatic, some metamorphosis internally and are born as adults Copyright Pearson Prentice Hall

Ch. 25- Amphibians Groups of Amphibians Female coiled around eggs Pink headed caecilian- W.Africa Copyright Pearson Prentice Hall

30-3 Ch. 25- Amphibians Copyright Pearson Prentice Hall

30-3 Ch. 25- Amphibians The word amphibian refers to the ability to live in hot climates. live in wet places. live both in water and on land. live in cold and hot climates. Copyright Pearson Prentice Hall

30-3 Ch. 25- Amphibians Amphibians that maintain their ancestral larval forms throughout life (paedomorphosis) are Caecilians Mud Puppies Salamanders Toads Copyright Pearson Prentice Hall

30-3 Ch. 25- Amphibians In a larval amphibians, gas exchange occurs through both the lungs and the skin. both the skin and the gills. the gills only. in a lung. Copyright Pearson Prentice Hall

30-3 Ch. 25- Amphibians The tympanic membrane in a frog enables it to hear. see. smell. taste. Copyright Pearson Prentice Hall

30-3 Ch. 25- Amphibians Which of the following is the order for salamanders? Anura Apoda Caudata Caecilians Copyright Pearson Prentice Hall

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