Class: Amphibians (Chapter 40) The name amphibian means "double life”

1. Class: Amphibians (Chapter 40) The name amphibian means "double life” For while adult amphibians usually live on land, their soft eggs must be laid in the water. References: Holt Biology text & resources http://z.about.com/d/animals/1/0/W/5/shutterstock_716539.jpg http://dnr.wi.gov/org/caer/ce/eek/critter/amphibian/index.htm

2. I. Amphibian evolution & orders • “Preadaptations”are adaptations in an ancestral group that allow a shift to new functions which are later favored by natural selection. • Lobe-finned fishes preadaptations that allowed transition to life on land: • bone structure • pouches in digestive tracts for gas exchange • nostrils • higher metabolism • efficient hearts • Lobbed finned fish were probably amphibian ancestors

3. A. Evolution of Amphibians • Amphibians and lobe-finned fishes share many anatomical similarities. • About 300 million years ago amphibians split into two main evolutionary lines. • One line included ancestors of reptiles, the other line included the ancestors of modern amphibians.

4. “From fin to limb”

5. B. 5Characteristics of Modern Amphibians: 1. Aquatic larval stage to terrestrial adult (metamorphosis) 2. Feet arewebbed(if they have feet)-no claws 3. Thin, moist skin with no scales • Use gills, lungs & skin for respiration - Aquatic young use gills & skin - Terrestrial adults lose gills, use lungs & skin 5. Eggs-lack multi cellular membranes or shells (usually laid in water or moist place)

6. C. 3 Orders of Modern Amphibians(about 4,500 species) 1. Anura- includes frogs and toads 2. Caudata -salamanders and newts 3. Gymnophiona- includes caecilians(legless tropical amphibians) (worm-like)

7. 1. Order Anura • Frogs & Toads • Found worldwide • Adapted for jumping • “anuran” means tail-less (no adults have tails) • Larvae are herbivores. Adults are carnivorous and will eat any animal they can capture • “Frog” & “Toad” are not formal, scientific groups • “Frog” refers to smooth, moist skin • “Toad” refers to rough, bumpy skin • There are 12 families. (see following pages) http://www.abdn.ac.uk/~nhi708/classify/animalia/chordata/amphibia/anura/

8. Family AscaphidaeAscaphids: 4 speciesMembers of this family have ribs and rudimentary tail-wagging muscles. There are two genera, one in New Zealand and one in North America. • Family PipidaePipid toads: 15speciesThese toads are entirely aquatic. Only the larvae have ribs. Both jaws are usually toothless. and all species are tongueless . Eyelids are sometimes present. • Family DiscoglossidaeDiscoglossids: 10 speciesDiscoglossids, found in Europe and Asia, have toothless lower jaws, and their ribs are present throughout life.

9. Family RhinophrydinaeThere is one speciesMexican burrowing toad, Rhinophrynus dorsalis: found among scrub and savanna on the coastal plains of Mexico and Guatemala. • Family PelobatidaePelobatids: 54 speciesThese small toads with minute teeth are found in Eurasia, North Africa and North America • Family BufonidaeToads: 300 speciesThe toads in this family have no upper teeth.

10. Family AtelopodidaeAtelopodids: 26 speciesThere are only two genera in this family of small, brightly coloured frogs, which live near forest streams in Central and South America. • Family HylidaeTree frogs: almost 600 speciesTreefrogs are adapted for life in trees, and have extra cartilage between the two end digits of the hands and feet, which gives them a better grip. • Family LeptodactylidaeLeptodactylids: 650 speciesMembers of this family are found in South and Central America, Australia and southern Africa. Several genera are adapted to the more arid areas of Australia. During the dry season they retire deep into the ground. Some species lay their eggs in burrows and rely on rainfall for development; the tadpoles' metamorphosis is so rapid that they become adults before the water evaporates.

11. Family RanidaeFrogs: hundreds of speciesThis group, which occurs on all continents, is unspecialised except for jumping - the specialisation common to all anurans. • Family RhacophoridaeOar-legged frogs: hundreds of speciesThese frogs, found in the tropics of Africa, Madagascar and eastern Asia , resemble tree frogs in their adaptations to living in trees. They have webbed hind feet. • Family MicrohylidaeMicrohylids: hundreds of speciesThis little-known family of burrowing and tree living forms is found in the Old and New World tropics, except western africa. The tadpoles hatch either at an advanced stage or completely metamorphosed

12. Differences/Similarities-Frogs & Toads http://www.enchantedlearning.com/coloring/amphibians.shtml

13. Cane Toad(The Unwanted Amphibian) • Also called the Giant Toad • Sprays poison out of it neck & is covered with poisonous mucus. • Until 1935 Australia did not have any toad species- the cane toad was introduced to combat a pest -sugar cane beetles . The toads can’t jump very high & did not eat beetles that were higher on plants- so they didn’t actually get rid of the beetles. • What they did do was mess up the ecosystem- • Fish who eat the tadpoles die. • Animals who eat toad adults die. • The museums have plenty of snakes preserved in jars which were killed by toad toxin so fast, the toad is still in their mouths unswallowed. • Local vets report that a couple dogs a month are brought in ill just from "mouthing" toads or from a toad fouling their waterdish.

14. American Toad • Very common in North America & PA • Warty skin contains glands that produce a poisonous milky fluid, =protection from predators. • Females lay their eggs in freshwater. Hatching occurs 3 to 12 days after, depending on the temperature of the water. The tadpoles group together and feed and grow for 40 to 70 days. • The sexes can be distinguished in two ways • Males have dark colored throats, of black or brown, while females have white throats and are lighter overall. • female American toads are larger than males. http://animaldiversity.ummz.umich.edu/site/accounts/information/Bufo_americanus.html

15. 2. Order Caudata • Salamanders (also called newts). • Amphibians that retain their tail as an adult. • Salamanders look like lizards without scales. • May be fully aquatic, fully terrestrial, or amphibious. • Some have no lungs, and respire through their skin only. • Reproduction: • Many reproduce in water. • Some reproduce on land, with no swimming larval stage. • Larvae and adults are carnivorous.

16. Cool Salamanders Marbled salamander Cave salamander Dusky salamander Green Salamander, Aneides aeneus www.naturalsciences.org/funstuff/notebook/her...

17. Salamanders of PA http://www.fish.state.pa.us/education/catalog/salamandersofpa.htm

18. PA Hellbender Salamanders that have four legs, a flat head, a paddle-like tail, beady little eyes and are called names like "snot otter" and "devil dog"? *One of the largest salamanders in the world, rivaled only by their cousins in China and Japan. *Once thrived in thousands of pristine streams throughout the eastern United States.  *Today, hellbenders are limited to relatively few healthy stream systems, mainly in areas that have remained isolated from human settlement.

19. 3. Order Gymnophiona • Includes Caecilians (legless amphibians that resemble small snakes). • Most are burrowing. They have small eyes beneath skin or bone, and are often blind. • All are carnivorous. • All are thought to have internal fertilization. • Some lay eggs which the female guards, others develop inside the female.

20. There are about 50 species of caecilians • phylum -Chordata, • subphylum -Vertebrata, • class -Amphibia, • order -Gymnophiona, • family –Caecilidae • All have teeth. • Chemosensory detection of prey • In a few species, young are born alive. • The young develop in the mother & use their jaws to scrape secretions, called “uterine milk” from the walls of the female reproductive tract

21. II. Amphibian Systems We will especially examine structures that are adaptations to living on land A Skin- no scales, moist, slimy, part of respiratory system B. Skeleton- supports body against pull of gravity C. Circulatory- 3 chambered hear, 2 circuit system D. Respiratory – larvae (gills & skin) adult (lungs & skin) E. Digestive – large elastic esophagus & stomach- for carnivores swallowing food whole. See parts. F. Excretory- in adult- kidney; ammonia (which is secreted as waste in fish & amphibian larva) istransformed to urea G. Nervous- 4 lobes & sensory organs H. Reproduction- depend on water, most external fertilization, metamorphosis.

22. A. Amphibian skin-2 important functions: 1. Respiration– -permeable to gases and water. -Mucous glands secrete a lubricant that keeps the skin moist in air. 2. Protection – -barrier from infections -secretes a foul-tasting or poisonous mucus that protects amphibians from predators.

23. B. The skeleton -supports the body against the force of gravity on land. • Vertebrae interlock & form a strong, rigid structure. • Strong limbs -standing, walking & jumping. • Pectoral & pelvic girdles transfer weight to the limbs.

24. C. Circulatory System The frog heart has 3 chambers: -2 atria -1 ventricle. -Though sharing a common chamber, oxygenated blood returning from pulmonary system has MINIMAL MIXING with deoxgenated blood returning from body.

25. Circulatory system has 2 loops 1. Pulmonary circulation - carries deoxygenated blood from the heart to the lungs and back to the heart. 2. Systemic circulation - carries oxygenated blood from the heart to the body and back to the heart. Note: • Fish have 2 chambers (and blood with Oxygen or returning from body is mixed)& • Mammals & birds have 4 chambered hearts. What advantages does a higher chambered, 2 loop circulatory system give ?

27. Advantages of higher blood Oxygen content. • In amphibians- which are still cold-blooded animals, separation of blood into 2 loops gives the advantage of higher oxygen content over fish (which have 1 loop & a 2-chambered heart) • In birds & mammals-The even larger oxygen supply allows these warm-bloodedorganisms to achieve thermoregulation (body temperature maintenance). • Note that in humans: our RBC are de-nucleated- giving even more O carrying capacity to blood cells.

28. D. 2 Forms of Respiration • Pulmonary respiration - respiration through the lungs • Cutaneous respiration - respiration through the skin

29. E. Digestive System • Parts include: • Pharynx, • Esophagus • Stomach • Accessory Glands • Liver • Gallbladder • Small intestine • The upper part of the small intestine is the duodenum. • The coiled middle portion of the small intestine is the ileum. • A membrane that holds the small intestine in place is called the mesentery. • Large intestine • Cloaca • Waste materials are stored in the cloaca and exit the body through the vent.

30. Frog Internal Anatomy

31. Do frogs have teeth? • Actually, yes! But not like in this silly picture! • Most frogs do in fact have teeth of a sort. They have a ridge of very small cone teeth around the upper edge of the jaw. These are called Maxillary Teeth. • Frogs often also have what are called Vomerine Teeth on the roof of their mouth. • The teeth are used to grip prey- NOT CHEW- frogs swallow prey whole. • Toads do not have teeth.

32. F. Excretory System • Kidneys • primary excretory organ • filter nitrogenous wastes from the blood. • Nitrogenous wastes are converted from ammoniato urea which is highly concentrated and helps conserve water. • Wastes + water = urine. • From the kidneys, urine flows to the cloaca & out of body.

33. G. Nervous • Brain • optic lobes -sight • olfactory lobes -smell. • cerebrumbehavior/learning. • cerebellum -muscular coordination. • medulla oblongata -controls heart rate and respiration rate. • Sensory organs • Nictitating membrane -a transparent moveable membrane that protects the eye. • Sound is detected by the inner ear. • tympanic membrane, or eardrum, • columella, a small bone

34. Frog nervous system

35. Frog Dissection Sites: http://biology.about.com/od/onlinedissections/ig/Frog-Dissection-Images/index_g.htm • http://www.ofsd.k12.wi.us/science/external.htm a. Large intestineb. Small intestine1. Lung lobes2. Heart3. Liver lobes4. Gall bladder5. Stomach6. Small intestine7. Testis8. Fat body9. Urinary bladder

36. H. Reproduction • Mating: • Females only respond to males of the same species. • Male clings to female in embrace = amplexus • Eggs and sperm are released into the water. • Fertilization is external. • Note-it is not always easy for a male to ID a female. If a male accidentally grabs a male- he makes a “release call”. The lack of a release call plus “plumpness” (signifying eggs) means “female” to a male frog. One researcher discovered a frog with an amplectic grip on a floating crab apple • (It was plump & had no release call)

37. Breeding • Frog and toad species • each have a distinctive call to attract females to breeding areas. • In shallow waters fertilized eggs will hatch into tadpoles and metamorphose into young frogs • Salamanders • nocturnal migration from upland wooded areas to ponds, marshes, and lakes. • Males- do not have breeding calls. Just show up at the breeding areas a day or two after the females to start courtship.

38. Metamorphosis • The tadpole grows and slowly changes from an aquatic larva into an adult in a process called metamorphosis. • Metamorphosis is controlled by a hormone called thyroxine.

40. Parental care • Some species guard their eggs until they hatch. • Increases the likelihood that the offspring will survive. • Some species sit on their eggs to prevent them from drying out. • The male Darwin’s frog carries the eggs in his vocal sacs until the larvae finish metamorphosis. • Female gastric brooding frogs swallow their eggs and the larvae mature in the stomach.

41. Surinam Toad • After mating, the male presses the eggs onto the females back • The eggs grow into toads under the skin on her back & then break out of the mothers skin with their front legs when ready. www.honoluluzoo.org www.molvray.com

42. Click here to see & here common northern USA frogs & toads (remember not to go thru firefox) http://dnr.wi.gov/org/caer/ce/eek/critter/amphibian/frogident.htm