The Amphibians

Class Amphibia

Anamniotic eggs

Larval forms are aquatic - use gills for respiration

Ectothermic -

Vs

Endothermic -

Homeothermic -

Vs

Poikilothermic -

Phylum Chordata

Subphylum Vertebrata

Class Amphibia

Order Gymnophiona (Apoda)

caecilians - South America, Africa, Southeast Asia. least known group of amphibians

- No limbs, no girdles - body long and segmented

- Burrowing animals - eyes reduced and covered with skin or bone

Internal fertilization - phallodeum formed by portion of cloacal wall

Females of many species exhibit parental care of young.

Order Caudata (Urodela) - Salamanders and newts - "having a tail"

Limbs at right angles to body. (Or reduced or absent)

Internal fertilization by spermatophores

Aquatic species lay eggs in water and have larval stage

Terrestrial species lay eggs on land and have direct development

Respiration: Cutaneous Gills Lungs

Plethodontidae -

Paedomorphosis -

Perrennibranchiate or

Permanently gilled

Order Anura (Salienta) - frogs and toads; "absense of tail"

Ranidae -

Hylidae -

Integument

Epidermis - keratin

Glands in epidermis:

1. Mucous

2. Serous

Dermis - chromatophores

Skeletal and Muscular System

Endoskeleton of bone and cartilage

vertebral column rigid; nine trunk vertebrae; urostyle; light skull

Respiration and Vocalization

cutaneous, buccal, lungs

Lungs predominate; skin used in hibernation

Use buccal pump to fill lungs

Vocal cords -

Circulation - 3-chambered heart

Double circulation vs single circulation of fishes

two atria and one ventricle

1. blood from body enters sinous venosus

2. from sinus venosus it enters right atrium

3. blood from lungs enters left atrium

- up to this point deoxygenated and oxygenated blood separated

4. both atria contract and push blood into single ventricle

5. some mixing but kept separate

oxygenated blood to systemic circuit

deoxygenated blood to pulmonary circuit (lungs)

both via the conus arterious

6. Trabeculae in ventricle and spiral valve in conus help keep blood separate

Nervous System

Forebrain -

Midbrain -

Hindbrain - cerebellum anteriorly and medulla posteriorly

cerebellum -

medulla -

Ear - simple; tympanic membrane (eardrum); stapes or columella bone in ear that transmits vibrations to inner ear

Vision - eyelids used to keep eye moist and foreign particles out.

rods and cones (for color).

Reproduction

amplexus

External fertilization

tadpoles