2. Amphibians
• Amphibians are cold-blooded .
• Frogs, toads, salamanders, newts, and
caecilians are all members of this class.
• Each exhibiting a larval stage with gills that
develops in an aquatic environment,
• External fertilization.
3. External structures
• Skin
• Breathing(nostrils)
• COLOR
• Chromatorphores
• Poison glands ( in skin)
• vocal sacs
• Harderian glands
• Serous glands
• Feet of Amphibians
4. skin
• Both oxygen and water are allowed to pass in
and out from skin.
• homeostasis and a sufficient level of respiration
maintained by skin.
• In order to sustain the necessary moisture level,
amphibians secrete mucus via glands contained
in the skin.
• serves as a protective layer around the body .
• Facilitates a proper salt and water balance within
the internal organs.
5.
6. Types of skin
Two types of skin:
• 1) Moist, slimy frog skin, and
• 2) drier, wartier toad skin
• Frogs' skin is critical to their survival
• Frogs don't swallow water; they get all the
moisture they need through their skin.
• Frogs must keep their skin moist. Otherwise,
oxygen can't pass easily through it and the frog
suffocates.
• Mucus keep it moist.
7. • Frog skin lose moisture easily but toad not .
• Frogs usually shed their skin in one week.
• process begins with the frog doing a lot of
twisting, bending, and stretching to loosen the
old skin.
• Then the frog pulls the skin over its head like a
sweater and -- usually – eats
8. Breathing
• Breathing is a gas exchange, taking in oxygen
from the surroundings and letting out carbon
dioxide.
• Tadpoles have gills for breathing but adult breath
through lungs.
• In all stages breathing is controlled by the throat.
• Gills lost during metamorphosis.
• Frogs breath with mouths closed. Their throat
movements pulls air through the nostrils to the
lungs.
10. • Gills also provide buoyancy in water.
• Frogs can also breath through their skin, with tiny
blood vessels, capillaries, under the outer skin layers.
• COLOR AND CAMOUFLAGE
• are over 3,000 different species of frogs and toads, sporting
just about every color in the rainbow.
• -- these colors help frogs blend in with their surroundings.
• Solomon , Island leaf frogs have dry leaf like color.
11. • Not all frogs try to blend in. Especially in the
tropics, there are wildly colored frogs of yellow,
blue, orange, red, and purple, often patterned
with bold stripes and spots. These bright colors
serve as a warning to predators: "Don't eat me;
I'm poisonous.
12. • Some frogs can change their color,
• according to light, temperature, humidity, or even mood. Fear
or excitement makes many frogs and toads turn pale.
• Another African frog is normally green, but turns white in the
heat of the day to reflect heat and keep cool.
• Chromatorphores:
• Color changes are created by special pigment cells called
chromatorphores.
• Inside these cells, grains of pigment cause color
changes by shifting their distribution.
• When the grains are packed together in the center of each
cell, the frog is light colored.
13. • When the pigment grains spreads out within each cell,
the frog's color darkens.
14. Poisonproduction in amphibians
• . All frogs have poison glands in their skin.
• All are not able to discourage predator but
Central and South America have especially
strong poisons in their skin is called poison dart
frogs.
• 170 different kinds of poison dart frogs.
• Most poisonous is golden poison frog have enough
poison to kill eight people.
•
16. vocal sacs
• Frogs make their calls with the help of one or
two pouches of skin called vocal sacs.
• The vocal sacs work like echo chambers to
amplify the sound.
• Frogs' ears, called tympanum, look like two flat
circles behind the eyes
• Helps during mating..
17. Harderian glands
• Found within the eye's orbit that possess a nictitating
membrane .
• The gland can be compound tubular. the fluid it secretes
(mucous, serous or lipid) varies between different groups of
animals.
• Functions:
• a location of immune response, a source
of thermoregulatory lipids, a source of pheromones, a site
of osmoregulation etc
18. Feet
• Frog's two front legs have four toes each, while the back legs
have five toes each..
• Aquatic frogs are likely to have long, strong legs with webbed
back feet to help them swim.
• Frogs that live on land tend to have shorter legs for walking
and climbing.
• Tree frogs have large, round toe pads that help them cling to
branches.
• Some frogs catch insects with a long sticky tongue.
