Chap 42 Amphibians

Amphibian Classification (with example) Kingdom = Animalia Phylum = Chordata Subphylum = Vertebrata Class = Amphibia Order = Caudata Family = Ambystomatidae Genus = Ambystoma Species = Ambystoma tigrinum Reference: Colbert, E.H Colbert’s evolution of the vertebrates.Wiley-Liss

Kingdom Animalia Eukaryotes –Organelles, large cells No cell walls Specialized cell types

Phylum Chordata Gill slits Dorsal nerve cord Notochord or vertebral column Amphioxus: a non-vertebrate chordate

Subphylum Vertebrata Vertebral column Skull (i.e., cranium)

Comparison of Vertebrate “Class” Traits (continued) Class RespirationBody temperature regulation Body covering Agnatha/Chondricthy es/ Osteichthyes GillsEctothermyScales AmphibiaGills, lungsEctothermySkin (smooth or warty) ReptiliaLungsEctothermyScales AvesLungsEndothermyFeathers, scales MammalsLungsEndothermyHair

1 st amphibians 1 st reptiles 1 st Homo sapiens

Evolutionary Relationships Amphibia Amniota Anapsida Diapsida Testudines (turtles) Mammalia Aves and other Dinosauria Squamata (snakes, lizards) Sphenodonta Crocodylia Synapsida Osteichthyes

1 st Amphibians (Devonian Period; mya) Eusthenopteron (a sarcopterygian fish) could be the ancestor of amphibians) Krohne (2000)

1 st Amphibians (Devonian Period; mya) Acanthostega (a sarcopterygian fish) could be the ancestor of amphibians

Other Early Amphibians Eryops (2-m long predator; mya) Forey (1988) Diplocaulus ( mya)

Modern Amphibians CaudataAnura

Modern Reptiles Order Testudines (turtles) Order Squamata (lizards, snakes)

02 Feb. 2009Amphibians.ppt14 Class Amphibians Less well adapted to terrestrial environment –Smooth skin, no scales (no keratin ?) –External fertilization depend on water for mating; sperm and eggs released together into water –No embryonic membranes, –Egg must stay moist usually in water, rarely in moist soil

Anamniotic egg Jellylike (unshelled; must develop in water) Small-sized (lack large membranes to nourish embryo and store waste) Amphibian egg mass

02 Feb. 2009Amphibians.ppt16 Amphibian Life Cycle Live in two habitats –exploit two sets of resources Produce large numbers of eggs No parental care, tadpoles “on their own”

02 Feb. 2009Amphibians.ppt17 Amphibian Life Cycle Advantages –Produce abundant offspring (less investment of matter, energy in each) –At least a few likely to survive. Disadvantages –Each egg/tadpole has small chance of survival wasteful –dependent on water, few can live far from surface water

02 Feb. 2009Amphibians.ppt18 Class Amphibians Order Caecilians –Legless (apoda), burrowing (resemble earthworms, but with skull & backbone) –Tropical –blind

02 Feb. 2009Amphibians.ppt19 Class Amphibians Order Urodela Order Salamanders (Urodela- tail visable) –Primitive form with four equal legs –Retain tail –Freshwater-Not found in Australia –Keep gills all life

Salamanders (Urodela) Mud puppies (East US) Axolotl Rocky Mountains

Compare Urodela to lizard

Some secrete poison or bad taste

Eastern American Hellbender reach inches

Japanese Hellbender reach 29 inches to 5 feet

New Salamanders discovered in Costa Rica, January otogalleries/salamander-pictures/photo4.html