amphibians
DESCRIPTION
Amphibians. Amphibia. Comes from the Greek amphi “both” and bios “life” Appeared during the Devonian period. Adaptations. Four limbs Lungs instead of gills Both internal & external nares (nostrils) Three chambered heart (two atria & one ventricle). - PowerPoint PPT PresentationTRANSCRIPT
Amphibians
Amphibia
• Comes from the Greek amphi “both” and bios “life”
• Appeared during the Devonian period
Adaptations
• Four limbs• Lungs instead of gills• Both internal & external nares (nostrils)• Three chambered heart (two atria & one
ventricle)
• Skin with keratin (protein) to prevent water loss
• Most with smooth, moist skin to take in dissolved oxygen
• Some with oral glands to moisten food they eat
• Ectothermic - body temperature changes with environment
• Show dormancy or torpor (state of inactivity during unfavorable environmental conditions)
• Hibernate in winter and aestivate in summer• Males with vocal sacs to croak • Digested system adapted to swallow prey whole • Well developed muscular system
Anura
• Frogs • Toads
Characteristics
• Both terrestrial & freshwater species • Tadpole with tail, gills, & two-chambered
heart • Adults without a tail, four limbs, & lungs • Frog skin smooth & moist for cutaneous
respiration, while toads is rough & warty (poison glands)
• Long hind limbs for jumping
• Aquatic larva called tadpole goes through metamorphosis to adult
• Metamorphosis controlled by hormone called thyroxine
Reproduction
• External fertilization with amplexus (male clasps back of female as sperm & eggs deposited into water)
• Eggs coated with sticky, jelly like material so they attach to objects in water & do not float away
• Eggs hatch into tadpoles in about 12 days
Tad pole life cycle
Caudata
• Newts and Salamanders
Characteristics
• Have elongated bodies with a tail & four limbs • Smooth, moist skin for cutaneous respiration • Size from a few centimeters long to 1.5
meters • Nocturnal when live in drier areas • Newts are aquatic species
• Lay eggs in water or damp soil • Some bear live young • May or may not go through tadpole stage
(some hatch & look like small adult)
• All newts are salamanders but not all salamanders are newts
Apoda
• caecilians
• Tropical, burrowing, worm like amphibians • Legless • Small eyes & often blind • Eat worms & other invertebrates • Average length 30 centimeters, but can grow
up to 1.3 meters • internal fertilization • Female bear live young