These legless wormlike These legless wormlike creatures average 30 cm creatures average 30 cm long, but they can be up to long, but they can be up to 1.3m long.1.3m long.

They have very small eyes They have very small eyes and are often blind. and are often blind.

They eat worms and other They eat worms and other invertebratesinvertebrates

The caecilian male deposits The caecilian male deposits sperm directly into the female, sperm directly into the female,

and the female bears live and the female bears live youngyoung

Trachystoma Trachystoma CharacteristicsCharacteristics

The Order Trachystoma The Order Trachystoma contains three living species contains three living species of mud eels, or sirensof mud eels, or sirens. .

Sirens live in the eastern Sirens live in the eastern United States and north United States and north eastern Mexico. eastern Mexico.

Frog External Frog External AnatomyAnatomy

The frog's powerful hind legs The frog's powerful hind legs are equally effective in jumping are equally effective in jumping or swimming. On land frogs sit or swimming. On land frogs sit with their hind legs folded with their hind legs folded against the body, poised to against the body, poised to jump at the first sign of dangerjump at the first sign of danger. .

Most frogs can make leaps Most frogs can make leaps many times their body many times their body lengthlength

Frog's eyes also work equally well Frog's eyes also work equally well in or out of water. Because the in or out of water. Because the eyes bulge out from the head, the eyes bulge out from the head, the frog can stay submerged while frog can stay submerged while literally "keeping an eye out" for literally "keeping an eye out" for predatorspredators

Eyelids that can blink protect Eyelids that can blink protect the frog's eyes from dust and the frog's eyes from dust and dehydrationdehydration

In addition to upper and lower eyelids, In addition to upper and lower eyelids, a third, transparent eyelid called a a third, transparent eyelid called a nictitating membrane covers each nictitating membrane covers each eyeball and joins the lower eyelideyeball and joins the lower eyelid

This membrane keeps the This membrane keeps the eyelid moist and protects it eyelid moist and protects it when it is under waterwhen it is under water

Frogs have eardrums, or Frogs have eardrums, or tympanic membranes, tympanic membranes,

which are circular which are circular structures located behind structures located behind

each eyeeach eye

Tympanic membrane

The frog's thick, moist skin The frog's thick, moist skin serves two important functionsserves two important functions— respiration and protection— respiration and protection

Glands secrete mucus to keep Glands secrete mucus to keep it from drying upit from drying up

Some glands secrete foul-Some glands secrete foul-tasting or poisonous tasting or poisonous substances that protect the substances that protect the frog from enemiesfrog from enemies

Some frogs, such as Some frogs, such as Hyla Hyla versicolor, versicolor, can change color can change color in order to blend with the in order to blend with the

environment.environment.

Count the number of

frogs in the picture?

Frog Internal Frog Internal AnatomyAnatomy

Skeletal SystemSkeletal System

The frog's spine The frog's spine has nine vertebraehas nine vertebrae

The cervical The cervical vertebra at the vertebra at the anterior end of the anterior end of the spine allows neck spine allows neck movement that movement that helps frogs catch helps frogs catch preyprey

Skeletal SystemSkeletal SystemPosterior to this Posterior to this

are seven trunk are seven trunk vertebrae, and vertebrae, and then a single then a single sacral vertebra sacral vertebra that supports the that supports the hind legshind legs

A long, slim bone A long, slim bone called the urostyle called the urostyle extends from the extends from the sacral vertebrasacral vertebra

Skeletal SystemSkeletal SystemBones of the pectoral Bones of the pectoral

girdle, which form the girdle, which form the shoulders, connect to shoulders, connect to the front legsthe front legs

They also provide the They also provide the primary protection to primary protection to the internal organs, the internal organs, since the frog has no since the frog has no ribsribs

The pelvic girdle The pelvic girdle connects to the hind connects to the hind legslegs

Digestive SystemDigestive System

Digestive SystemDigestive SystemMost frogs feed on insects, and Most frogs feed on insects, and

their digestive system is adapted their digestive system is adapted to their dietto their diet

A frog's tongue is an excellent A frog's tongue is an excellent insect catcherinsect catcher. . The frog simply The frog simply flicks out its long sticky tongue, flicks out its long sticky tongue, curls it around its prey, and pulls curls it around its prey, and pulls the insect back into its mouth. the insect back into its mouth. Then the frog snaps its mouth shut Then the frog snaps its mouth shut and swallowsand swallows. .

Digestive SystemDigestive SystemFrogs have two Frogs have two

types of teeth types of teeth that hold on to that hold on to prey. A row of prey. A row of maxillary teeth maxillary teeth

line the line the perimeter of the perimeter of the upper jaw. Two upper jaw. Two

patches of patches of vomerine teeth vomerine teeth

project from project from bones in the roof bones in the roof

of the mouthof the mouth..

Digestive SystemDigestive System Sometimes the frog Sometimes the frog

blinks, pulls its eyes blinks, pulls its eyes inward, and presses inward, and presses them against the roof them against the roof of its mouth. This of its mouth. This action helps push the action helps push the food down its throatfood down its throat

Digestion in frogs Digestion in frogs takes place in the takes place in the alimentary canal, alimentary canal, which includes the which includes the esophagus, stomach, esophagus, stomach, small intestine, large small intestine, large intestine, and cloacaintestine, and cloaca

Circulatory SystemCirculatory SystemAn adaptation to the An adaptation to the

greater oxygen needs of greater oxygen needs of land animals is a more land animals is a more efficient circulatory efficient circulatory system than the fish's system than the fish's two-chambered heart. two-chambered heart.

The amphibian's three-The amphibian's three-chambered heart chambered heart partially mixes partially mixes oxygenated with oxygenated with deoxygenated blood and deoxygenated blood and pumps the blood pumps the blood throughout the body at throughout the body at higher pressure than higher pressure than does the fish's heartdoes the fish's heart

The left atrium The left atrium receives oxygenated receives oxygenated blood from the lungs, blood from the lungs, and the right atrium and the right atrium receives receives deoxygenated blood deoxygenated blood from the body. from the body.

Both the atria empty Both the atria empty into the ventricle, the into the ventricle, the main pumping main pumping chamber of the heart. chamber of the heart.

In the ventricle In the ventricle oxygenated and oxygenated and deoxygenated blood deoxygenated blood mix partially and are mix partially and are pumped to the lungs pumped to the lungs and the rest of the and the rest of the bodybody..

Blood to body

Deoxygenated blood from bodyR

Oxygenated blood from lungs

From the right atrium From the right atrium the blood enters the the blood enters the single ventricle. The single ventricle. The ventricle then contracts, ventricle then contracts, pumping some blood to pumping some blood to the lungs to receive the lungs to receive oxygen and some to the oxygen and some to the rest of the body. rest of the body.

The blood going to the The blood going to the body leaves the body leaves the ventricle through the ventricle through the conus arteriosus, a conus arteriosus, a large vessel that lies large vessel that lies against the front side of against the front side of the heartthe heart

This vessel divides into a right and This vessel divides into a right and a left truncus arteriosus, which a left truncus arteriosus, which immediately branch again into immediately branch again into three arches that carry blood to three arches that carry blood to various parts of the body. various parts of the body.

Deoxygenated blood travels in Deoxygenated blood travels in veins back to the right atrium from veins back to the right atrium from the various regions of the body.the various regions of the body.

Oxygenated blood returns from Oxygenated blood returns from the lungs to the left atrium via the the lungs to the left atrium via the pulmonary veinspulmonary veins

Respiratory Respiratory SystemSystem

Tadpoles respire, or Tadpoles respire, or exchange carbon dioxide exchange carbon dioxide and oxygen, through gillsand oxygen, through gills

Respiratory Respiratory SystemSystem

Adult frogs lose the gills but can Adult frogs lose the gills but can respire in three ways: through respire in three ways: through the lungs, through the skin, and the lungs, through the skin, and through the mouth. through the mouth.

Respiration through the lungs is Respiration through the lungs is called pulmonary respiration. called pulmonary respiration.

A frog breathes by changing the A frog breathes by changing the volume and pressure of air in its volume and pressure of air in its mouth while either opening or mouth while either opening or closing its nostrilsclosing its nostrils

Respiratory SystemRespiratory System Air moves from the throat to the Air moves from the throat to the

lungs through a slit-like passage lungs through a slit-like passage called the glottis.called the glottis.

Because the frog's lungs are small, Because the frog's lungs are small, cutaneous respiration, or cutaneous respiration, or respiration through the skin in respiration through the skin in both air and water, is very both air and water, is very important, especially during important, especially during estivation or hibernation. estivation or hibernation.

Oxygen can diffuse across the Oxygen can diffuse across the lining of the mouth and into the lining of the mouth and into the blood.blood.

Frogs use mouth breathing for Frogs use mouth breathing for only a relatively small amount of only a relatively small amount of their respirationtheir respiration..

Excretory SystemExcretory SystemUrine and wastes from the digestive Urine and wastes from the digestive

system are eliminated through the system are eliminated through the anus. anus.

When a frog is in water, its permeable When a frog is in water, its permeable skin allows the water to enter its body. skin allows the water to enter its body.

Frogs that Frogs that live live primarily in water rid primarily in water rid themselves of excess water by themselves of excess water by excreting a large volume of very dilute excreting a large volume of very dilute urine.urine.

Frogs that live mainly on land Frogs that live mainly on land conserve water by producing a small conserve water by producing a small volume of more concentrated urine.volume of more concentrated urine.

Excretory SystemExcretory System Amphibians eliminate two primary types of Amphibians eliminate two primary types of

metabolic waste products—carbon dioxide metabolic waste products—carbon dioxide from respiration and waste com pounds from from respiration and waste com pounds from the breakdown of foodsthe breakdown of foods. .

Are the primary excretory organs and lie on Are the primary excretory organs and lie on either side of the spine against the dorsal either side of the spine against the dorsal body wall. The kidneys filter nitrogenous body wall. The kidneys filter nitrogenous wastes from the bloodwastes from the blood

The Nervous SystemThe Nervous SystemThe frog brain is more The frog brain is more

complex than the fish complex than the fish brain, enabling the frog to brain, enabling the frog to contend with a more varied contend with a more varied environment. environment.

The optic lobes, which The optic lobes, which control vision, lie behind control vision, lie behind the cerebrum.the cerebrum.

The cerebellum, a small The cerebellum, a small band of tissue lying at right band of tissue lying at right angles to the long axis of angles to the long axis of the brain, is the center of the brain, is the center of balance and coordinationbalance and coordination..

Nervous SystemNervous SystemThe medulla oblongata lies at the The medulla oblongata lies at the

back of the brain and joins the spinal back of the brain and joins the spinal cord. It controls organ functions.cord. It controls organ functions.

Ten pairs of cranial nerves extend Ten pairs of cranial nerves extend out directly from the brain.out directly from the brain.

The spinal cord transmits signals The spinal cord transmits signals from all parts of the body to the from all parts of the body to the brain and from the brain back to the brain and from the brain back to the body. body.

The spinal nerves branch from the The spinal nerves branch from the spinal cord to various parts of the spinal cord to various parts of the body.body.

Reproductive Reproductive SystemSystem

Both male and female frogs have Both male and female frogs have internal sex organsinternal sex organs

The male frog's fore leg muscles The male frog's fore leg muscles and first fingers swell and first fingers swell

These swellings help the male These swellings help the male maintain his grasp on the femalemaintain his grasp on the female

The reproductive system of the The reproductive system of the male frog includes two bean-male frog includes two bean-shaped creamy white or shaped creamy white or yellowish testes located near the yellowish testes located near the kidneyskidneys

Sperm cells develop in the testes Sperm cells develop in the testes and pass through tubes to the and pass through tubes to the kidneys and urinary ductskidneys and urinary ducts Male System

Reproductive Reproductive SystemSystem

Female frogs a pair of Female frogs a pair of large, lobed ovaries large, lobed ovaries containing thou sands of containing thou sands of tiny immature eggs lie near tiny immature eggs lie near the kidneysthe kidneys

During the breeding season During the breeding season eggs enlarge, mature, and eggs enlarge, mature, and burst through the thin burst through the thin ovarian walls into the body ovarian walls into the body cavity. cavity.

They remain in structures They remain in structures called ovisacs until called ovisacs until ovulation is complete and ovulation is complete and then leave the body then leave the body through the cloacae through the cloacae opening.opening.

Female System

Reproductive Reproductive SystemSystem

The vast majority of eggs The vast majority of eggs and tadpoles are eaten by and tadpoles are eaten by predators such as fish, predators such as fish, birds, snakes, and turtles. birds, snakes, and turtles. Some species of frogs Some species of frogs havehave

The vast majority of eggs The vast majority of eggs and tadpoles are eaten by and tadpoles are eaten by predators such as fish, predators such as fish, birds, snakes, and turtlesbirds, snakes, and turtles. .

Amplexus

MetamorphosisMetamorphosisNewly hatched tadpoles live off Newly hatched tadpoles live off

yolk stored in their bodies. yolk stored in their bodies. They gradually grow larger and They gradually grow larger and develop three pairs of gills. develop three pairs of gills.

Tadpoles have a two-Tadpoles have a two-chambered heart. Tadpoles can chambered heart. Tadpoles can also regenerate injured or lost also regenerate injured or lost body parts such as a leg or tail.body parts such as a leg or tail.

Legs grow from the body, and Legs grow from the body, and the tail disappears.the tail disappears.

MetamorphosisMetamorphosis

The mouth broadens, The mouth broadens, developing teeth and jaws. A developing teeth and jaws. A saclike bladder in the throat saclike bladder in the throat divides into two sacs that divides into two sacs that become lungs. The heart become lungs. The heart develops a third chamber.develops a third chamber.

A hormone called thyroxin A hormone called thyroxin circulates throughout the circulates throughout the bloodstream and stimulates bloodstream and stimulates metamorphosis. metamorphosis.

The cells of the tad pole are The cells of the tad pole are genetically programmed to genetically programmed to respond to thyroxin at the respond to thyroxin at the appropriate stage of appropriate stage of development.development.