Lecture 6 Class Amphibia amphi both bios life

Lecture 6: Class Amphibia amphi ‘both’ + bios ‘life’ Part 2: Anurans (Frogs and Toads) Ch. 25 pp. 555 -565 Anura (an, without + oura, tail)

III. Order Anura A. General Characteristics 1. Distribution -5280 species of un-tailed amphibians -Live in temperate and tropical regions, usually near water -Found on all continents except Antarctica

III. Order Anura A. General Characteristics 2. Hibernation in Temperature Regions - In oxygen-rich water of pools and streams. Use fat/glycogen stores for energy. -In humus of forest floor; 35% of extracellular fluid is frozen. Accumulate glucose and glycerol to prevent formation of ice crystals.

III. Order Anura A. General Characteristics 3. Predators -Snakes, birds, turtles, raccoons, humans, fish (on tadpoles) -Defense: Inflating lungs Leaping Poison glands Biting Camouflage

III. Order Anura B. Body System 1. Integumentary (skin) Two layers in skin Epidermis – molts Dermis – glandular n Waterproofing mucous n Poisonous secretions n Contain chromatophores Xanthophores: yellow, orange, red Iridophores: silvery, light reflecting Melanophores: brown, black

III. Order Anura B. Body System 2. Skeletal/Muscular a. Bony endoskeleton Rigid from head to tail for support Skull: light-weight, protects nose, eyes, brain Vertebrate: 9 trunk and a urostyle (fused caudal vertebrae) Limbs: 3 main joints (hip, knee, ankle/shoulder, elbow, wrist); jointed digits b. Major Muscles Anterior/ventral: pull limbs forward and toward midline Posterior/dorsal: pull limbs back and away from body

III. Order Anura B. Body Systems 3. Respiratory a. Skin/Mouth Breathing (like salamanders) Cutaneous (skin): Vascular nets underneath the skin Buccal (mouth): Vascular membranes in the mouth b. Lungs Positive –pressure builder; fill lungs by forcing air into them Supplied by pulmonary arteries c. Gills Present in larvae d. Vocal cords In larynx-better developed in males; species specific sound patterns

III. Order Anura I I B. Body Systems 4. Circulatory System n 3 -chambered heart n One ventricle (pump) Two atria (holding sacs) Double loop system Atrium fills with blood from body goes to lung to pick up oxygen back to other atrium out ventricle to rest of body 3 -chambered heart

III. Order Anura B. Body Systems 5. Nervous System a. Increased Cephalization n Forebrain: coordinates olfaction (smelling) n Midbrain: coordinates vision n Eyes with nictitating membrane Retina with rods and cones (color vision) Hindbrain: coordinates hearing and balance Tympanic membrane = eardrum Columella=stapes; transmits sound to inner ear

III. Order Anura B. Body Systems 6. Digestive System a. Feeding Carnivorous as adults; arthropods, molluscs, and worms Herbivorous as larvae; pond algae b. Digestive Tract Short: mouth > esophagus > stomach > small intestines > large intestine (colon) > cloaca c. Metabolism Fat and glycogen storage Ectotherms with low metabolism

III. Order Anura C. Body Systems 7. Reproduction a. Dioecious b. Breeding n n n Breed, feed, and grow only during warm seasons (ectothermic) External fertilization in water when females’ eggs are mature Amplexus: male grasps female and discharges sperm over eggs c. Metamorphosis

III. Order Anura I C. Environmental Issues Biological Indicators of the Environmental Health Frog Malformations -Increased incidence of malformed frogs n Malformed Frog Research by Teenagers Go to link and watch video clip: http: //pbskids. org/dragonflyt v/show/malformedfrogs. h tml