Amphibians

Characteristics of Amphibians Vertebrate Lives in water as larva; land as adult (some exceptions) Breathes with lungs as adult Moist skin with mucus glands No scales and claws

Evolution of Amphibians First amphibians during Devonian Period Transitioned from water to land Breathe air Protect eggs and themselves from drying out Support against the pull of gravity

Evolution Continued… Adaptations evolved to live at least part of life out of water. Stronger bones in limbs and limb girdles; more efficient movement Lungs and breathing tubes Sternum or breastbone for shield and support.

Lungs Pelvic Girdle Leg Bones: The legs of a land vertebrate must be strong enough to hold its weight. Skin: The skin and the lining of the mouth cavity of many adult amphibians are thin and richly supplied with blood vessels. Watery mucus is secreted by glands in the skin.

As Adults lungs are richly supplied with blood vessels and folds that increase surface area

Class Amphibia Includes frogs, toads, salamanders, and caecilians. Small and diverse class Due to extinction of most amphibians during Permian Period (climate changes) Low, swampy habitats disappeared

Feeding Tadpoles Adults Filter feeders or herbivores (algae) Intestine breaks down hard plant material Adults Carnivores Sticky tongues to capture insects

Respiration Gas exchange through skin and gills (larval stage) Lungs, skin, and lining of mouth cavity (adult stage) Lungless amphibians: thin lining of mouth cavity and skin

Circulation Double loop First loop Oxygen-poor blood from heart to lungs and skin Oxygen-rich blood from lungs and skin to left atrium Second loop Oxygen-rich blood from heart to rest of body Oxygen-poor blood from body back to heart

Amphibian Heart Three separate chambers Left atrium Right atrium To body, lungs and skin From Body From Lungs Three separate chambers Left atrium Right atrium Ventricle Right atrium Left atrium Ventricle

Excretion Kidneys to filter wastes from blood Urine excreted; travels from ureters to cloaca to outside or stored in urinary bladder Heart Lung Kidney Ureter Urinary bladder Cloaca

Reproduction Females lay eggs in water; male fertilizes them externally (most amphibians) Internal fertilization (salamanders) After fertilization; frog eggs encased in sticky, transparent jelly Yolk of egg nourishes embryo

Movement Wiggle tails; flattened tails for propulsion (larva) Adult salamanders walk or run Frogs and toads: well developed hind limbs (jump long distances)

Response Well developed nervous and sensory systems Nictitating Membrane Moist and transparent Located inside regular eyelid Can be closed over the eye Tympanic Membrane Eardrums located on each side Lateral Line Used to detect movement in water

Frog Digestion Food enters the mouth  esophagus  stomach  small intestine  large intestine  cloaca Cloaca: muscular cavity where solid waste, urine, eggs and sperm exit body Liver, pancreas and gall bladder excrete enzymes that aid in digestion Frog Movie

Mouth Esophagus Liver Gallbladder Stomach Small intestine Pancreas Large intestine (colon) Cloaca

Frog Reproduction Adults ready to breed in 1 to 2 years Eggs laid in water (external fertilization) Fertilized eggs  tadpoles (several days to few weeks) Tadpoles gradually lose tails and gills, grow limbs.

Frog Metamorphosis Adult Frog Fertilized eggs Young Frog Tadpoles

3 Groups of Amphibians Salamanders Frogs and Toads Caecilians

Salamanders Long tails and bodies 4 legs Carnivorous Live in moist woods (adults) Tunnel under rocks and rotting logs

Frogs and Toads Ability to jump Long legs = lengthy jumps (Frogs) Short legs = short hops (Toads) Frogs closely tied to water Toads closely tied to moist woods

Caecilians Legless animals that live in water or burrow in moist soil Feed on small invertebrates (termites) Fish-like scales embedded in their skin

Frog Dissection

External Anatomy

Tympanum

External Nares

Internal Nares

Vomerine Teeth

Tongue

Eustachian Tube

Maxillary Teeth

Dorsal Muscular Anatomy

2. Pterygoideus 3. Temporalis 4. Masseter 5. Depressor mandibularis 6. Trapezius 11.Latissimus dorsi 14.External oblique 17.Gluteus 18.Piriformis 20.Vastus externus 25.Gracilis minor 26.Gastrocnemius 28.Semimembranosus 29.Biceps femoris

4.Masseter 5.Depressor mandibularis 6.Dorsalis scapulae 10.Trapezius

55.Depressor mandibularis 10.Trapezius

Ventral Muscular Anatomy

7.Deltoid 9.Pectoralis major 12.Rectus abdominus 13.Linea alba 14.External oblique 30.Mylohyoid

7 37.Deltoid 9.Pectoralis major 13.Linea alba 20.Rectus femoris 21.Adductor magnus 22.Sartorius 24.Gracilis major 25.Gracilis minor 26.Gastrocnemius 27.Achilles tendon 30.Mylohyoid

Internal Anatomy

Cerebellum

Cerebrum

Liver

Heart 2 Atria 1 Ventricle

Stomach

Large Intestine

Spleen

Gall Bladder

Pancreas

Lung

Kidney

Oviduct

Ovaries/ Eggs

Testes/ Sperm

Sperm Duct