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  1. 1. Topic: external structures and locomotionin amphibiansDesigned by afifa (uog)
  2. 2. Amphibians• Amphibians are cold-blooded .• Frogs, toads, salamanders, newts, andcaecilians are all members of this class.• Each exhibiting a larval stage with gills thatdevelops in an aquatic environment,• External fertilization.
  3. 3. External structures• Skin• Breathing(nostrils)• COLOR• Chromatorphores• Poison glands ( in skin)• vocal sacs• Harderian glands• Serous glands• Feet of Amphibians
  4. 4. skin• Both oxygen and water are allowed to pass inand out from skin.• homeostasis and a sufficient level of respirationmaintained by skin.• In order to sustain the necessary moisture level,amphibians secrete mucus via glands containedin the skin.• serves as a protective layer around the body .• Facilitates a proper salt and water balance withinthe internal organs.
  5. 5. Types of skinTwo types of skin:• 1) Moist, slimy frog skin, and• 2) drier, wartier toad skin• Frogs skin is critical to their survival• Frogs dont swallow water; they get all themoisture they need through their skin.• Frogs must keep their skin moist. Otherwise,oxygen cant pass easily through it and the frogsuffocates.• Mucus keep it moist.
  6. 6. • Frog skin lose moisture easily but toad not .• Frogs usually shed their skin in one week.• process begins with the frog doing a lot oftwisting, bending, and stretching to loosen theold skin.• Then the frog pulls the skin over its head like asweater and -- usually – eats
  7. 7. Breathing• Breathing is a gas exchange, taking in oxygenfrom the surroundings and letting out carbondioxide.• Tadpoles have gills for breathing but adult breaththrough lungs.• In all stages breathing is controlled by the throat.• Gills lost during metamorphosis.• Frogs breath with mouths closed. Their throatmovements pulls air through the nostrils to thelungs.
  8. 8. Anuranshavemuchmorecomplexlungs thenotheramphibians,suchassalamanders. Becausetheyaremoreactiveandhavehighbodytemperature.
  9. 9. • Gills also provide buoyancy in water.• Frogs can also breath through their skin, with tinyblood vessels, capillaries, under the outer skin layers.• COLOR AND CAMOUFLAGE• are over 3,000 different species of frogs and toads, sportingjust about every color in the rainbow.• -- these colors help frogs blend in with their surroundings.• Solomon , Island leaf frogs have dry leaf like color.
  10. 10. • Not all frogs try to blend in. Especially in thetropics, there are wildly colored frogs of yellow,blue, orange, red, and purple, often patternedwith bold stripes and spots. These bright colorsserve as a warning to predators: "Dont eat me;Im poisonous.
  11. 11. • Some frogs can change their color,• according to light, temperature, humidity, or even mood. Fearor excitement makes many frogs and toads turn pale.• Another African frog is normally green, but turns white in theheat of the day to reflect heat and keep cool.• Chromatorphores:• Color changes are created by special pigment cells calledchromatorphores.• Inside these cells, grains of pigment cause colorchanges by shifting their distribution.• When the grains are packed together in the center of eachcell, the frog is light colored.
  12. 12. • When the pigment grains spreads out within each cell,the frogs color darkens.
  13. 13. Poisonproduction in amphibians• . All frogs have poison glands in their skin.• All are not able to discourage predator butCentral and South America have especiallystrong poisons in their skin is called poison dartfrogs.• 170 different kinds of poison dart frogs.• Most poisonous is golden poison frog have enoughpoison to kill eight people.•
  14. 14. Thepoison-arrowfrog(Dendrobatestinctorius) ofSouthAmerica.Scientistshaverecentlydiscoveredthatthepoisonssecretedbythesefrogscanalsobeusedtoblockpaininhumans..
  15. 15. vocal sacs• Frogs make their calls with the help of one ortwo pouches of skin called vocal sacs.• The vocal sacs work like echo chambers toamplify the sound.• Frogs ears, called tympanum, look like two flatcircles behind the eyes• Helps during mating..
  16. 16. Harderian glands• Found within the eyes orbit that possess a nictitatingmembrane .• The gland can be compound tubular. the fluid it secretes(mucous, serous or lipid) varies between different groups ofanimals.• Functions:• a location of immune response, a sourceof thermoregulatory lipids, a source of pheromones, a siteof osmoregulation etc
  17. 17. Feet• Frogs two front legs have four toes each, while the back legshave five toes each..• Aquatic frogs are likely to have long, strong legs with webbedback feet to help them swim.• Frogs that live on land tend to have shorter legs for walkingand climbing.• Tree frogs have large, round toe pads that help them cling tobranches.• Some frogs catch insects with a long sticky tongue.
  18. 18. Catchingfast-movinginsectsrequiresgoodeyesight.Frogslargeeyesseeawiderangeofcolorsandalsoseewellindimlight.Eyeshelpittoseeinalldifferentdirectionswithoutmovingitshead.
  19. 19. • The positioning of the eyes -- on top of head --allows a frog to sit in the water with only its eyesand nose above the surface.