Transcript Amphibians - Cobb Learning

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
Amphibians
Classification
Kingdom Animalia
Phylum Chordata
Class Amphibia
Order 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
Amphibians
More 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
Amphibians
Review Characteristics
Amphibians
Respiration:
• Larva exchange gases through both their skin
and gills
• Adults exchange gases through both their skin
and lungs
• Cutaneous Breathers: Breath through their
skin
Amphibians
Circulation:
• 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
Amphibians
Reproduction:
• 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.
Amphibians
Reproduction:
• 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.
Amphibians
Reproduction:
• 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.
Amphibians
Reproduction:
• 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
Amphibians
Reproduction:
• 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.
Amphibians
Reproduction:
• 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
Amphibians
Unusual 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
Amphibians
Unusual 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
Amphibians
Unusual 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.
Amphibians
Feeding:
• Tadpoles are filter feeders or herbivores (graze on algae)
(Salamander larvae are carnivores.)
• Adults are strictly carnivores
• Cloaca: where digestive wastes, urine, and
eggs or sperm leave the body
Feeding:
Amphibians
• 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 Organs
Vision:
• 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
Tympanic
Membrane
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.
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.
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
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.
Amphibians
Habitat:
• 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 Toads
Toads Continued…
– Parotoid (poison) glands behind the eyes
– Lay eggs in long chains
Frog or Toad
Answer:
• The use of the common names “frog” and
“toad” has no taxonomic justification.
• ALL members of the Order Anura are frogs!
• Only members of the Family Bufonidae are
considered “true toads”
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
Newt
Caudal 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
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
Other Problems facing 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
Amphibians
Largest amphibian
Japanese Giant Salamander
140 lbs, 6 feet long
Amphibians
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
Smallest amphibian
Brazilian Golden Frog
A few grams
9.8 millimeters long
What has a frog done for you lately?
Frogs eat pest insects
One 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 research
Chemicals in the skin of a South American Frog provide a
painkiller that is more powerful than morphine and less
addictive!
Frog Pregnancy Test
A 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.
The End