AMPHIBIANS A. Arizona has frogs, toads, and salamanders GENERAL STRUCTURE: FROGS + TOADS VERSUS SALAMANDERS Adult Frogs and Toads: Four limbs- hind limbs larger and modified for jumping. No distinct neck. No distinct tail Adult Salamander: Four limbs of equal size. Distinct neck Distinct tail AMPHIBIAN CHARACTERISTICS A. Life Cycle+ Amphibios or Double life- Adult land based, breathing with skin and lungs. Larvae need an aquatic environment. They are fish-like using gills for respiration. GENERAL STRUCTURE B. Amphibian skin is smooth + moist possessing numerous mucous glands. They are capable of breathing through their skin or cutaneous breathing. This is especially important while they are dormant. North American toads have toxic skin glands as do many central + South American tree frogs. AMPHIBIAN CHARACTERISTICS C. Amphibians have 4 limbs. D. Reproduction involves an external fertilization and an egg laying or oviparous pattern. Eggs have a jelly-like covering and will dry out if not in a moist environment. E. Thermoregulation: Amphibians are heterotherms and ectotherms. NUTRITION AND REPRODUCTION III Nutrition: The larval stage (tadpoles in frogs + toads and waterdogs in salamanders) are omnivores, while the adults are carnivores. IV. Reproduction: A. The breeding season for frogs + salamanders is spring, while toads breed during monsoon rains of July and August. B. Behavior: 1. Amphibians call/croak for, sex recognition, species recognition and to establish a territory. AMPHIBIAN REPRODUCTION 2. Amplexus is the mating embrace of amphibians. 3. Time of development from egg to adult: a. Sonoran Desert toad = 30 days b. Woodhouse toad = 34-45 days c. Red Spotted Toad = 40-60 days d. Bullfrog = 2 years Spadefoot Toad = 9-21 days. This is some of the fastest vertebrate development known. To speed up development and win the survival race, spadefoot tadpoles do the following: 1. Secrete growth inhibitors to slow down the growth of competitors. 2. Become cannibals, eating smaller + weak tadpoles. 3. Have the ability to withstand higher temperatures than the adults. 4. Swarm to absorb more heat. 5. Have an omnivorous mode of nutrition. ANPHIBIAM DIVERSITY IN ARIZONA According to this reference, Arizona has 1 native species of salamander and 24 species of frogs and toads, including the Arizona Tree Frog, the Arizona state amphibian. AMPHIBIANS IN TROUBLE A. Batrachochytrium dendrobatidis (Bd for short) is a type of pathogen chytrid fungus that has attacked at least 200 species of amphibians globally. 1. The fungus attacks keratin a protein found in the mouthparts of tadpoles and the skin of the adult. 2. Several theories exist as to what kills the frogs, including introduction of toxins, or enzymes, disruption of skin + opportunistic infections. AMPHIBIANS IN TROUBLE 3. It appears that the original source of this disease may have been the African clawed frog, which (1930s) was shipped around the world for use in human pregnancy tests. 4. There is evidence that the American bullfrog also may be responsible for some of the spread of the disease. 5. In the Sonoran desert region, Bd has been found in a variety of frog species, tree frogs and even the tiger salamander. 6. Bd is considered the worst ever recorded disease among global wildlife. Left unchecked, it may contribute to the extinction of 100’s if not 1000’s of species of amphibians.