Chap 42Amphibians

Amphibian Classification(with example)

Kingdom = Animalia

Phylum = Chordata

Subphylum = Vertebrata

Class = Amphibia

Order = Caudata

Family = Ambystomatidae

Genus = Ambystoma

Species = Ambystoma tigrinum

http://fwie.fw.vt.edu/VHS/

Reference: Colbert, E.H. 2001. Colbert’s evolution of the vertebrates.Wiley-Liss

Kingdom Animalia

• Eukaryotes– Organelles, large cells

• No cell walls

• Specialized cell types

http://www-class.unl.edu/bios201a/

Phylum Chordata • Gill slits• Dorsal nerve cord• Notochord or

vertebral column

Amphioxus: a non-vertebrate chordate

Subphylum Vertebrata

• Vertebral column• Skull (i.e., cranium)

http://medic.med.uth.tmc.edu/Lecture/labeled/bs106001.gif

http://face-and-emotion.com/dataface/physiognomy/media/cranium_side.jpg

Comparison of Vertebrate “Class” Traits (continued)

Class Respiration Body temperature regulation

Body covering

Agnatha/Chondricthyes/

Osteichthyes

Gills Ectothermy Scales

Amphibia Gills, lungs Ectothermy Skin (smooth or

warty)

Reptilia Lungs Ectothermy Scales

Aves Lungs Endothermy Feathers, scales

Mammals Lungs Endothermy Hair

http://www.cr.nps.gov/museum/exhibits/dino/geotime/

1st amphibians

1st reptiles

1st Homo sapiens

Evolutionary Relationships

Amphibia

Amniota

Anapsida

Diapsida

Testudines (turtles)Mammalia

Aves and other Dinosauria

Squamata (snakes, lizards)

Sphenodonta

Crocodylia

Synapsida

Osteichthyes

1st Amphibians (Devonian Period; 408-360 mya)

Eusthenopteron (a sarcopterygian fish) could be the ancestor of amphibians)

http://www.lautringer.de/Alle_Dinosaurier_in_Kaiserslau/Dinosaurier_Album_1/

Krohne (2000)

1st Amphibians (Devonian Period; 408-360 mya)

Acanthostega (a sarcopterygian fish) could be the ancestor of amphibians

http://www.nhm.ac.uk/hosted_sites/paleonet/vop/glimpse/lab-m.jpg

http://www5b.biglobe.ne.jp/~hilihili/keitou/mizika/sarcopterygii/sarco-gazou/acantho.jpg

Other Early Amphibians

Eryops (2-m long predator; 360-320 mya)

Forey (1988) http://www.geocities.co.jp/HeartLand-Suzuran/3621/

Diplocaulus (290-245 mya)

Modern Amphibianshttp://www.herpnet.net/Iowa-Herpetology/

http://fwie.fw.vt.edu/VHS/http://www.herpnet.net/Iowa-Herpetology/

http://www.mybitoftheplanet.com/2002/

Caudata Anura

Modern Reptiles

Order Testudines (turtles)

Order Squamata (lizards, snakes)

http://www.herpnet.net/Iowa-Herpetology/images/

02 Feb. 2009 Amphibians.ppt 14

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

http://epod.usra.edu/archive/images/egg_mass.jpg

02 Feb. 2009 Amphibians.ppt 16

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. 2009 Amphibians.ppt 17

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. 2009 Amphibians.ppt 18

Class Amphibians• Order Caecilians

– Legless (apoda), burrowing (resemble earthworms, but with skull & backbone)

– Tropical– blind

02 Feb. 2009 Amphibians.ppt 19

Class AmphibiansOrder 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 Hellbenderreach 17-21 inches

Japanese Hellbenderreach 29 inches to 5 feet

New Salamanders discovered in Costa Rica, January 2004

• http://news.nationalgeographic.com/news/2008/01/photogalleries/salamander-pictures/photo4.html