KEY CONCEPT Amphibians evolved from lobe-finned fish.

Q: Why are frogs so good at baseball? Q: Why are frogs so good at baseball? A: Because they catch a lot of flies... Amphibian Trivia Amphibians can breathe with skin, gills, or lungs All amphibians lay their eggs in water Salamanders, frogs, toads, and caecilians are all amphibians Amphibians are herbivores Frogs are the largest group of amphibians True False Q: Why are frogs so good at baseball? A: Because they catch a lot of flies...

Amphibians were the first animals with four limbs. Tetrapods are vertebrates that have four limbs. Includes all vertebrates that live on land and some aquatic animals The snake is considered a tetrapod!!! The fossilized remains of Tiktaalik roseae indicate it was a transitional species between fish and tetrapods.

How do these adaptations help on land? Amphibians are animals that can live both on land and in water. A number of adaptations allow amphibians to live on land. large shoulder and hip bones mobile, muscular tongue middle ear breathe through skin or with gills or lungs How do these adaptations help on land?

Amphibians return to the water to reproduce. Why? Amphibians use many strategies to keep their eggs wet. lay eggs directly in water lay eggs on moist ground wrap eggs in leaves brood eggs in pockets on the female’s back

Tadpoles are aquatic larvae of frogs. Newly hatched: Live off the yolk in their body Develop gills: 3 pairs 2 chamber heart Mouth will open and allow it to eat Can regenerate body parts During metamorphosis, tadpoles develop into their adult form. Legs grow, Tail disappears Mouth broadens: Develops teeth and jaws Lungs develop from a saclike bladder in the throat Heart develops a 3rd chamber Lose the ability to regenerate Not all amphibians undergo metamorphosis.

Tadpoles undergo many changes during metamorphosis Gills are reabsorbed and lungs develop Circulatory system sends blood to the lungs Tail fin/tail is reabsorbed Grows limbs Systems reorganize…Nervous, Skeletal, Muscular Digestive system rebuilt adult frog young frog tadpoles fertilized eggs

Frogs are the largest amphibian group and include toads. There are over 3000 species of frogs. Glands in the skin of frogs and toads contain poisons that help to protect them from predators. Live in all environments except poles and driest deserts Adult frogs will eat any animal they can catch

Cold Blooded/Ectotherm: Body fluctuates up or down depending on the outside temperature Protects itself by going dormant under unfavorable conditions: torpor Hibernation is torpor in the winter Estivation is torpor in the summer

Anatomy of a Frog: Circulatory System 1. Right Atrium: Receives deoxygenated blood from the body 2. Left Atrium: Receives oxygenated blood from the lungs 3. Ventricle: Both the Left and Right atrium empty into here Main pumping chamber of the heart Oxygenated and Deoxygenated blood mix partially and are pumped to the lungs and the rest of the body. Using your knowledge of the human heart, name two ways the frog heart is different

Left Atrium Right Atrium Sinus venosus Ventricle Posterior Vena Cava

Anatomy of a Frog: Nervous System Olfactory Lobes: Sense of smell Optic lobe: Controls vision Spinal Nerves: Branch off of the Spinal cord to various parts of the body Spinal Cord: Transmits signals back and forth between the body and brain Medulla Oblongata: Controls organ functions Cerebellum: Balance and coordination Cerebrum: Controls voluntary nervous activity

Nervous System

Anatomy of a Frog: Digestive System Tongue-Mouth-Swallows by pressing eyes to the roof of the mouth (Tongue attached in front of mouth: sticky end) Teeth Maxillary Teeth: Perimeter of upper jaw Vomerine Teeth: Roof of Mouth Alimentary Canal: Digestion occurs here Includes: esophagus, stomach, small intestine, large intestine and Cloaca Small Intestine: Upper Portion: duodenum Coiled middle: ileum Mesentery: Fanlike and holds the intestine in place Large Intestine: Cavity: Cloaca Waste exits through the cloacal opening, or anus Liver: produces Bile, digestive enzyme, stored in the gallbladder Pancreas: secretes digestive enzymes into the small intestine

stomach duodenum pancreas Small intestine Large intestine ileum spleen

Mesentery connecting small intestine

Fat Bodies Small intestine Large intestine

Anatomy of a Frog: Excretory System CO2 mostly excreted through skin Waste from food: Kidneys: Primary excretory organ, filter waste from blood Water and Nitrogenous waste is called urine, excreted through anus

Frog Kidney

Anatomy of a Frog: Respiratory System Respiratory System: Tadpoles use gills; Adult: Use lungs 3 ways to respire: 1.Through Lungs: Pulmonary Respiration 2.Through Skin: Cutaneous Respiration 3.Through Mouth: Diffusion through the lining of the mouth.

Anatomy of a Frog: Reproductive System Male: Testes produce sperm Female: Ovaries produce eggs: Leave body through the cloacal opening Fertilization: One time per year Mating call to attract female When the female releases the eggs the male discharges sperm on them; direct external fertilization In 12 days the eggs hatch into tadpoles Frogs produce tons of eggs…Why?

Frog Eggs Ovaries with Frog Eggs

Frog Testes Testes

1 4 2 3 10 9 8 7 6 5

Mouth Tongue attached at front of mouth; 2 sets of teeth to hold prey 2. External Nares (nostrils) at the top of the frogs head; allows frog to breathe while partially submerged under water 3. Forelimbs for balance; shorter than hind limbs 4. Digit grasping 5. Eyes Nictitating membrane: Third eyelid: Keeps eyeball moist and protects eye under water 6. Tympanic membranes External eardrums; senses vibrations for hearing; transmits sounds to internal ear 7. Dorsal side “backside”; darker for camouflage 8. Skin Respiration and protection (camouflage), Mucus Glands: Secretes lubricant that keeps skin _____, Secretes foul tasting or poisonous substance for protection 9. Hind limbs – used for jumping and swimming; feet are webbed; up to 6x longer than forelimbs 10. Ventral side “belly” side of frog; lighter in color for camouflage

Mouth External Nares Nictitating Membrane Eye Tympanic Membrane

Internal Mouth

Maxillary teeth Vomerine teeth Internal Nares Eustachian tube esophagus glottis tongue

Esophagus Liver Lung Gallbladder Pancreas Stomach Small Intestine Spleen Large Intestine Cloacle Cloacle Opening Kidneys Testes Ovaries/Eggs Oviducts Large Intestine Urinary Bladder Cloacle Opening

Heart Fat Bodies Urinary bladder Liver

List two reasons why amphibians must live in moist environments. Compare and contrast the frog heart to the human heart. List three changes that occur during metamorphosis. Amphibians are very sensitive to changes in their environment, which is why they are called Biological Indicators. Why might this be? Why does amphibian reproduction require a moist environment? List two adaptations of amphibians abd briefly describe why each is important for life on land. List the major structures involved in each of the following systems: Respiratory, Digestive, Reproductive and Excretory