Amphibians

HERPETOLOGY = the study of reptiles and amphibians

Class Amphibia

What is an amphibian? 4000+ species AMPHIBIAN = GREEK FOR AMPHIBIOS WHICH MEANS “DOUBLE LIFE”

Amphibians VERTEBRATES Metamorphosis HIBERNATE OR ESTIVATE DEPENDING ON CLIMATE Scientist infer that amphibians evolved from lobe-finned fishes called crossopterygians.

Amphibian Characteristics 1st true tetrapod vertebrates Bony skeletons with four limbs Exceptions: Caecilians (limbless) and Sirens (forelimbs only) Feet are webbed and the toes lack claws. They have moist, smooth, thin skin with no scales.

Amphibians are ectotherms, which means their blood temperature rises and falls with that of the surrounding environment Copyright Cmassengale

Respiration Larva (tadpoles) breathe with gills Adult frogs have lungs Some amphibians keep gills all their life, mudpuppy

Respiration Lungs are internal - allows exchange of oxygen and carbon dioxide between blood and air Greater the surface area the greater the amount of oxygen can be absorbed Lungs are not as efficient as gills, but there is more oxygen in air than in water so lungs do not have to be

Respiration Cutaneous respiration- “Skin breathing” Supplement oxygen intake w/ moist skin Limited by body size Many terrestrial salamanders have no lungs at all  breathe through skin and mouth cavity

Circulation Heart is a double loop, with 3 chambers  2 atria and a ventricle that is partly divided

Double Loop Circulation Due to moving to land and requiring more oxygen for their muscles, amphibians developed a double loop in their circulatory system Amphibians have pulmonary veins that deliver oxygen rich blood back to the heart and then to the remainder of the body

Larvae have two-chambered hearts; adults have three-chambered hearts and well-developed circulation. Copyright Cmassengale

CLOACA sperm, egg, solid wastes, and urine leave the body through this opening

Feeding Larva (tadpoles) are usually herbivores Adults are usually carnivores Digestive tract Mouth  esophagus  stomach  small intestine  colon (large intestine) cloaca

Excretion Kidneys filter cellular (liquid) waste = urine Kidneys  ureters  small urinary bladder  cloaca

Response Well developed nerves and nervous system – complex brain with cerebrum, cerebellum, medulla oblongata Eyes move in socket and are protected by nictitating membrane – transparent membrane that covers the eye when amphibian is in the water Tympanic membrane = eardrums Lateral line systems = detect water vibrations

Amphibians enter a state of dormancy or torpor when conditions are unfavorable. They often bury themselves in mud or leaves, emerging when conditions are better. Copyright Cmassengale

Amphibian Reproduction Require water because eggs lack shells to prevent water loss Yolk of egg nourishes developing embryo External Fertilization - female releases eggs and male fertilizes externally-called amplexus

Reproduction Larvae commonly called tadpoles, process by which tadpoles become adults - metamorphosis A few species care for eggs by incubating in mouth, or on their back or stomach!

METAMORPHOSIS Series of changes that occur as an organism grows

larva  young adult adult Amphibians have many prominent characteristics that are adaptations to a life spent both on land and in water: They change from an aquatic larval stage to a terrestrial adult form. Eggs  larva  young adult adult

Amphibian Metamorphosis It affects nearly every organ in the tadpole’s body Tadpoles: Herbivorous, Aquatic, Single-loop circulation, Gills Frogs: Carnivorous, Terrestrial or aquatic, Double-loop circulation, Lungs

Amphibian Evolution Biologist conclude that amphibians appeared during the late Devonian period, about 345 million years ago. Copyright Cmassengale

Paleontologists have discovered fossils of a species that provides the missing evolutionary link between fish and the first animals that walked out of water onto land about 375 million years ago. The newly found species, Tiktaalik roseae, has a skull, a neck, ribs and parts of the limbs that are similar to four-legged animals known as tetrapods, as well as fish-like features such as a primitive jaw, fins and scales.

Amphibian Adaptations for Life on Land Bones became stronger Lungs to breath air Limbs to walk on land Sternum (breast bone) and ribs to protect internal

History Carboniferous Period = Age of Amphibians Climate change caused habitats to disappear 3 groups survive today - salamanders, frogs, and caecilians

Amphibian Groups Kingdom Animalia …..Phylum Chordata ……...Subphylum Vertebrata ………….Class Amphibia Order Urodela Order Anura Order Apoda

Order Anura Means “Without a tail” Frogs and Toads Copyright Cmassengale

There are about 3,500 known species of frogs and 300 kinds of toads They are found on every continent except Antarctica Frogs have smooth, moist skin Toads have dry, bumpy skin Copyright Cmassengale

Some types spend their entire life in or near water, but others live mainly on land and come to the water only to mate Copyright Cmassengale

Some frogs and toads are climbers that dwell in trees or burrowers that live underground. Copyright Cmassengale

See videos at http://video.nationalgeographic.com

Order Urodela Means “visible tail” Salamanders and Newts Copyright Cmassengale

Copyright Cmassengale

Salamanders, typical members of the Order Urodela, have elongated bodies, long tails, and smooth, moist skin Copyright Cmassengale

Compared to the anurans, salamanders are less able to remain on dry land, although some can live in dry areas by remaining inactive during the day Copyright Cmassengale

Salamander lay their eggs in water and like anurans they hatch into swimming larva Salamander eggs Copyright Cmassengale

Other species can reproduce in damp land environments Other species can reproduce in damp land environments. Eggs laid on land hatch into miniature adult salamanders Marbled Salamander Copyright Cmassengale

Order Apoda Means “without feet” Caecilians Copyright Cmassengale

tropical, burrowing worm-like amphibian that is often legless Copyright Cmassengale

Have fish-like scales

These creatures average 30 cm, but they can be up to 1.3m long. They have very small eyes and are often blind. They eat worms and other invertebrates

The caecilian male deposits sperm directly into the female, and the female bears live young

Amphibian Ecology Number of living species is declining Environmental threats: Decreasing habitat Pollution Fungal infections Introduced predators Increasing human population

Amphibian Habitats forests grasslands lakes, ponds, marshes rivers and streams

Quick Check 1. How many chambers does the heart of a frog have? ____ 2. The opposite of terrestrial is ___________ 3. A series of changes that occur from birth to adulthood (tadpole → frog) is called _______________ 4. Tadpoles breathe using _______. 5. The main organ of excretion is the _____________ 6. Urine, eggs, and other wastes exit through the __________ 7. The opposite of carnivorous is _____________ 8. A caecilian is an amphibian that does not have ________ 9. The study of reptiles and amphibians is ___________ 10. To what kingdom do frogs belong? _________ what phylum? ____________ what class ? _____________