Amphibian- “Double Life” - Water and land Chapter 19-Amphibians Amphibian- “Double Life” - Water and land

Amphibian Characteristics 1st true tetrapod vertebrates Bony skeletons with four limbs Exceptions: Caecilians (limbless) and Sirens (forelimbs only) Many w/webbed feet Thin moist skin; no scales Breathe w/ lungs (Internal, bag-like organ that exchanges oxygen and carbon dioxide with the air and blood) Exception: Lungless salamanders Larvae- gills Cutaneous respiration- “Skin breathing” Supplement oxygen intake w/ moist skin Limited by body size

Double-Loop Circulation

Amphibian Characteristics Partially divided heart: Atrium separated into left and right sides by septum, ventricle is not Right side sends oxygen-poor blood to lungs Left side send oxygen-rich blood to organs Double-loop circulation: Two large veins (pulmonary veins) return oxygen-rich blood from lungs to heart Blood pumped to tissues at higher pressure than fish Systemic circulation- Blood flow to the body

Class Amphibia Order Anura- Frogs and toads Order Urodela (Caudata) – Salamanders, sirens, newts, waterdogs, mudpuppies Order Gymnophiona (Apoda)- Caecilians

Class Amphibia

Order Anura- Frogs and Toads Anura- without a tail Adult carnivores Skin with mucus and some with poison glands Sticky tongue, hinged at the front, attaches to prey Vomerine teeth- two small nobs help hold in prey Hind legs adapted for jumping Frogs are smooth w/ longer legs Toads are rough w/shorter legs Most frogs depend on water for life cycle Females lay eggs in water Males fertilize them Larvae are tadpoles Gills Feed on algae Incomplete metamorphosis Develop into adult frogs Rate depends on species and food

Leopard Frog and Fowler’s Toad

Goliath Frog- Conraua goliath - Largest frog in world - Found in Cameroon

Poison-Dart Frogs- Family Dendrobatidae

Frog Characteristics Cloaca- Chamber opening to outside of body Tympanic membrane- thin membrane that detects vibration (eardrum) Eustachian tubes- equalize pressure on eardrums Skin has mucus glands Mucus is poisonous or foul tasting in most Nictitating membrane- transparent eyelid Two teeth in roof of mouth Swallow food whole Cloaca- Chamber opening to outside of body Serves as exit for wastes and gametes Oviduct- carries eggs to cloaca Vocal Sacs- Expandable membranes that collect air after passing over vocal cords for louder croaking

Amplexus

Order Urodela (Caudata- with a tail) Salamanders 369 species of salamanders, newts, sirens, amphiuma, waterdogs, and mudpuppies Elongated bodies w/long tails Smooth, moist skin; Require moisture External fertilization in water or moist area Internal fertilization- females insert sperm packet into cloaca Larvae gilled, carnivorous, smaller version of adult Some retain gills as adults (neoteny- never lose larval characteristics)

Axolotl Salamander that never loses its gills Neoteny Found in N. america

Other Urodela (Caudata) Newt Water dog Amphiuma Mud puppy

Order Caudata- Sirens Aquatic salamanders Have only front extremities Maintain gills throughout life Some can vocalize Most likely external fertilization

Order Apoda- Caecilians Apoda- without legs Tropical, burrowing amphibians Small, bony scales embedded in skin Legless Carnivorous Male deposits sperm directly into female Females may have live young or lay eggs