Amphibians

Amphibians• Herpetology is the study of amphibians & reptiles

Amphibians• Amphibian means “double life”

• Live both in water and on land

Includes:

> Frogs/Toads

> Newts/Salamanders

> Caecilians

AmphibiansClassification

Kingdom Animalia Phylum Chordata

Class AmphibiaOrder Anura (Frogs/Toads)

Order Caudata (Salamanders/Newts/waterdogs)

Order Gymnophiona (Caecilians)

Amphibians

Characteristics• Ectothermic: animals whose body heat is regulated by the external environment = “cold blooded”

• Lives in water as a larva/Land as an adult• Breaths with gills as larva/Lungs as an adult

• Moist skin with mucus glands• Lacks scales and true claws

AmphibiansMore Characteristics

Do not have adaptations for a complete terrestrial (land) existence Are tetrapods: tetra = 4 pod = foot Fresh water dependent Have the ability to breath through their skin

Many contain poisons in their skin

AmphibiansVideo Questions

1. Amphibian means ______________.

2. How are larval amphibians like fish?

3. After an amphibian’s transformation, they not only look different, but they occupy ________.

4. Amphibians have been around for about ___.

5. What were amphibians first to do?

AmphibiansReview Characteristics

AmphibiansRespiration:

• Larva exchange gases through both their skin and gills

• Adults exchange gases through both their skin and lungs

• Cutaneous Breathers: Breath through their skin

AmphibiansCirculation:• Have a 3 chambered heart

• “Double loop” circulatory system

• 1st Loop– Carries oxygen-poor blood from heart to lungs & skin, and takes oxygen-rich blood from lungs & skin back to the heart.

• 2nd Loop– Carries oxygen-rich blood from heart to the rest of the body, and oxygen-poor blood from body back to the heart

AmphibiansReproduction:

• Many frogs show Sexual Dimorphism.

• Sexual Dimorphism: Differences between the bodies and colors of males and females

• In some species, males and females are hard to tell apart.

• In such species, male frogs often produce a release call when clasped by another male. • During mating season, researchers can use release calls to tell which frogs are male and which are female.

AmphibiansReproduction:

• Amphibian eggs do not have shells, and will dry out if they are not kept moist

• Most eggs are laid in water

• MOST parents abandon their eggs after they lay them

Amphibians

Reproduction:

• Male frogs are typically smaller than females

• Once a female has been found, he will grasp her trunk with his forelimbs. This embrace is

called amplexus.

AmphibiansReproduction:

• Eggs are fertilized externally.

• Males do NOT have a penis

• As the female discharges eggs (usually in water), the male sheds sperm over the eggs.

• Large masses of eggs are called frogspawn.

AmphibiansReproduction:

• When there is NO parental care when raising the young, the female releases about 200 eggs

– More energy is spent making large amounts of eggs, while none is spent caring for the young

• If there is parental care when raising the young, the female releases only a few eggs

– Less energy is spent making so many eggs, and more is used in caring for the young

AmphibiansReproduction:• Eggs are encased in a sticky, transparent jelly that attaches the egg mass to underwater plants

• The jelly nourishes the developing embryos until they hatch into larvae called tadpoles/pollywogs.

Embryo: Early developmental stage after fertilization.

AmphibiansReproduction:

• After the babies hatch, they will undergo metamorphosis.

Metamorphosis: a profound change in form from one stage to the next in the life history of an organism

AmphibiansUnusual Reproduction:

Darwin’s Frog (Rhinoderma darwinii)

• Females lay their eggs on moist soil

• When the eggs hatch, the male “swallows” the tadpoles to store them in his specialized vocal sacs.

• The tadpoles stay there through metamorphosis (6 weeks), and then the mature froglets are released

Amphibians

Unusual Reproduction:

Midwife Toad (Alytes)

• After fertilization, the male wraps the eggs around his legs to protect them from predators

• When they are ready to hatch, the male wades in the water to release his tadpoles

AmphibiansUnusual Reproduction:

Surinam Toad (Pipa pipa)

• The female releases about 60-100 eggs

• After fertilization, the male pats down the eggs onto the female’s back which embeds them into her skin

• Pockets are formed around each egg

• The larvae develop through the tadpole stage into froglets, eventually pushing themselves out of their pocket

AmphibiansUnusual Reproduction:

Coast Foam Nest Tree Frog

• When summer rainfall starts males call from branches overhanging water

• The female churns her secretions into a large white foam nest into which she deposits her eggs.

• These are then fertilized by the males.

• The eggs develop into tadpoles inside the hardening nest.

• After about 5 days the tadpoles become active and fall into the water below, living there until the metamorphosis is complete.

Foam Nest

AmphibiansFeeding:

• Tadpoles are filter feeders or herbivores (graze on algae)

• Adults are strictly carnivores

• Cloaca: where digestive wastes, urine, and eggs or sperm leave the body

AmphibiansFeeding:

• Some have teeth

• Maxillary teeth: very small cone shaped teeth around the upper edge of the jaw

• Vomerine teeth: on the roof of the mouth

• There are NO teeth on the lower jaw

• They use their teeth to catch and hold onto prey as they swallow them whole, not for chewing

Sense OrgansVision:• The eyes are covered by a transparent, movable membrane called a nictitating membrane.• Is a transparent or translucent third eyelid present in some animals that can be drawn across the eye for protection and to moisten the eye while also keeping

visibility.

Nictitating

Membrane

Sense Organs

Hearing:• The inner ear detects sound. • Sounds are transmitted to the inner ear by the tympanic membrane, or eardrum.• Sound 1st strikes the tympanic membrane, and vibrations are sent to the fluid-filled inner ear.

Tympanic Membrane

Frog Communication

Amphibians Communication:

• Frogs & toads produce a rich variety of sounds, calls, and songs during their courtship & mating rituals.

• The “callers” are usually males

• Advertises their:– Location– Mating readiness– Willingness to defend their territory

Amphibians Communication:

• Certain species that have a narrow mating season due to ponds that dry up have the most vigorous calls

• Calls differ from one species to another

• When competing with hundreds or thousands of other frogs, together they perform a chorus call where each frog calls in turn. Few individual’s calls are drowned out using this method.

*Video

Amphibians

Communication:

• Some calls are so loud, they can be heard a mile away

• Calls are made by passing air through the larynx in the throat

• The sound is amplified by one or more vocal sacs, membranes of skin under the throat or on the corner of the mouth.

• These vocal sacs distend during amplification of the call

* Video

Croaking Frogs

Poisons• Many frogs contain mild toxins that make them unpalatable to potential predators.

• All toads have large poison glands called parotoid glands — located behind the eyes on the top of the head.

Parotoid gland

Parotoid gland

Poisons

• The chemical makeup of toxins in frogs varies from irritants

– Hallucinogens: Causes change in perception, thought, emotion, & consciousness

– Convulsants: Causes seizures

– Neurotoxins: Acts specifically on nerve cells causing paralysis – Vasoconstrictors: Causes constriction of blood flow

• Some frogs, such as some poison dart frogs, are especially toxic.

• Native to Central and South America.

• These amphibians are often called "dart frogs" due to indigenous Indians use of their toxic secretions to poison the tips of blowdarts

• Although all poison dart frogs are at least somewhat toxic in the wild, levels of toxicity vary considerably from one species to the next, and from one population to another.

AmphibiansHabitat:

• Arboreal: Living in trees

• Terrestrial: Living on land

• Aquatic: Living in fresh water

• None are Marine: Living in salt water

Frogs & Toads

Is it a Frog or a Toad???

All toads are frogs!!!

All frogs are NOT toads!!!

Huhhhhh….?

Frogs or Toads• Frogs are typically:

– Strong, long, webbed hind feet

– Adapted for leaping, swimming, & climbing – Aquatic or semi-aquatic

– Smooth moist skin

– Tend to lay eggs in clusters

Frogs or Toads• Toads are typically:

– Terrestrial/dryer climates

– Dry warty skin

– Stubby bodies with short hind legs

– Short hops or walks…does not leap

Frogs or ToadsToads Continued…

– Parotoid (poison) glands behind the eyes

– Lay eggs in long chains

Frog or Toad• The use of the common names “frog” and “toad” has no taxonomic justification.

• ALL members of the OrderOrder Anura are frogs!

• Only members of the FamilyFamily Bufonidae are considered “true toads”

Answer:

Salamanders & Newts

Order Caudata Caudata: Salamanders & Newts cauda = tail ata = to bear Possess a tail throughout life

Salamanders * Live in moist forest-floor litter * Have aquatic larvae

Newts* Live mostly in water* Many retain caudal fin on tail

Salamander

NewtCaudal fin

Caecilians

Order Gymnophiona

Gymnophiona: Caecilians

Gymnos = naked ophineos = like a snake

Worm-like burrowers that feed on worms & other invertebrates Skin covers their eyes & are nearly blind

Threats to Amphibians

• Habitat loss is the biggest threat to frogs.

• Small wetlands that are used as breeding areas by frogs are being filled, drained, and developed.

• Marshes and swamps are rapidly being replaced by parking lots, strip malls, and residential developments.

• Small wetlands (ditches, backwaters, temporary pools, and even mud puddles) are vitally important to local amphibians, and many people fail to realize the importance of them in the biotic community.

Amphibians

• The moist, permeable skin of frogs is sensitive to numerous pollutants, which is one reason why frogs are considered a good indicator species of ecosystem health.

• Industry, mining, agriculture, and the application of lawn and garden chemicals all release toxins into the environment.

• Many of these toxins can affect tadpole and adult survival.

Amphibians

• A wide range of fungal, bacterial, and viral diseases affect amphibians.

• Also, a tapeworm parasite causes severe limb malformities.

• Climate change & drought

• Slaughter for the frog leg trade

• Capture for the pet trade

AmphibiansOther Problems facing amphibians:

AmphibiansLargest amphibian

Japanese Giant Salamander140 lbs, 6 feet long

Goliath Frog• The world's largest frog is the Goliath frog.

• Goliath frogs live in Africa where they spend their days eating insects, crustaceans, fish, and other amphibians.

• A Goliath frog grows up to 13 inches in body length and with outstretched legs can reach over 2 1/2 feet in length.

• If you're thinking 'Mmmmm, frog legs', the Goliath frog weighs about 7 pounds so one frog should suffice as a meal but you'd better be quick when catching them as they can jump up to 10 feet in a single bound.

Amphibians

AmphibiansSmallest amphibian

Brazilian Golden Frog A few grams

9.8 millimeters long

What has a frog done for you lately?

Frogs eat pest insectsOne dwarf puddle frog can eat up to 100 mosquitoes in one

night!

Frogs provide us food Tastes like chicken!

Frogs are used in medical research to test new drugs

Frog skin has benefited our pharmacological researchChemicals in the skin of a South American Frog provide a

painkiller that is more powerful than morphine and less addictive!

How does a frog know you’re knocked up?

Frog Pregnancy TestA human female’s urine is injected into a lymph sac of

the South African Clawed frog in the morning. If she is pregnant, her pee will cause a female clawed frog to lay

eggs within 8-12 hours. Male frogs produce sperm in response to the injection.

The frogs are responding to hCG (human chorionic gonadotropin), a hormone present in only pregnant women. Most modern

pregnancy tests respond to this hormone as well.

Funny Video!

The End