Amphibians (1957)

[Music] if you've ever gone swimming you probably know that it's a lot of fun to try different ways of swimming this boy is doing a stroke that sometimes called the frog kick can you guess why now we can see how the frog kick probably got its name the strong hind legs of the Frog help make it a powerful swimmer frogs spend most of their lives in or near water but they can also live on land animals that live part of their lives in water and part on land are called amphibians this word means both kinds of life frogs and their close relatives the Toads have no tails and are sometimes called the tailless amphibians amphibians with tals include salamanders this is one of the many kinds of salamanders the salamanders of a certain family are called nutes they're quite common and are often found in pools or damp places in the woods another amphibian that has a tail is the mud puppy using its gills to breathe it spends all its life in the water in spite of these differences all amphibians have moist soft skins and all of them live in or near the water a pond in Spring is a good place to look for amphibians coming out of their winter sleep hear that it's a Cricut frog another amphibian the the cricket frog gets its name from The Sound it makes do you think it sounds like a Cricket air fills its throat which puffs up like a balloon this vocal sack as it's called makes the sound louder and so although it's a very small animal the Frog's voice can be heard a long way off in the spring female frogs lay their eggs in the water a dark mass of eggs can be seen just below this Frog's body these tiny eggs which have no shells are held together and protected by a mass of jellylike stuff which covers them in about 2 weeks these eggs are ready to hatch here we see the tiny eggs greatly enlarged by the camera baby frogs that emerge from the eggs are called tadpoles as you can see baby tadpoles look quite different from adult frogs they have tails like fish and like fish baby tadpoles breathe through gills they have no lungs here we see the gills on either side of a tadpole's head oxygen which the tadpole needs to live is taken from the Water by the gills after a few days these gills disappear they have been replaced by gills inside the tadpole's body water is taken through the tadpole's mouth passes over the gills where it gives up oxygen and then passes out through a little hole on the left side of the body called the spiracle this word means a breathing hole here is a tadpole gulping water through its mouth and here on the tadpole's left side is the spiracle through which the water comes out besides getting oxygen the tadpole also finds food in the water tadpoles eat very small plants in time the growing tadp develops two hind legs and after a few more weeks two front legs grow at the same time the tadpole's gills disappear and its lungs begin to form now the growing tadpole looking more and more like a frog must come to the surface often to gulp air its mouth is also changing becoming wider for a while the tadpole stops eating gradually its body uses up the material in its tail for nourishment as the tail gradually disappears The tadpole completes its change in into an adult frog the change is called metamorphosis this word means a change of form most amphibians undergo metamorphosis salamanders for instance have gills during their early life in the water somewhat like those we saw on the tadpoles as adults salamanders live on land and most of them have lungs all amphibians have a skin without hair or scale s which must be kept moist most amphibians do some breathing through their moist skin and so usually stay where they can get to water or damp places the Frog for example does a little breathing through its skin both in water and in air but it breathes chiefly with its lungs all amphibians have backbones and are called vertebrates this word means bones that turn most amphibians in the adult stage have legs although water frogs have webbed hind feet that help them in swimming toads and some land frogs have little or no webbing on their feet tree frogs have small suction cups on their toes these tiny discs help them climb trees and shrubs amphibians feed on snails worms small fishes and other tiny animals found in the water but for most amphibians the main food is insects watch the Frog and grasshopper closely did you see it with lightning speed the Frog flicked out its long sticky tongue and seiz the insect let's watch the Frog again we'll slow the action down in the camera there it is even in slow motion the whole thing happens very quickly by closing its mouth the Frog helps push the food down into its stomach because of their eating habits frogs and other amphibians especially toads are very helpful to man in destroying harmful insects amphibians are protected from their many enemies by camouflage is it easy to see the N among the Pebbles some amphibians such as this tree frog not only have coloring that makes them hard to see but they can slowly change it this tree frog is green like the leaf it sits on when the same frog is on Brown Bark what happens very slowly the color changes until it's somewhat brownish like the bark now it would be much harder for an enemy to see the Frog unless it moved there's another way the Frog can escape enemies by jumping powerful hind legs are used to make amazing leaves the hind legs are not only used on land but also in water whether in the water or on land all amphibians produce so little body heat that they are as cold as the air or water that surrounds them we say they're cold blooded as the weather gets cold in the fall and lakes and ponds begin to freeze over some amphibians go down to the bottom of the lake or Pond here they lie very quietly sometimes partly buried in mud or gravel all their life actions continue but are slowed down the Frog Almost stops breathing and the very little oxygen it needs to stay alive is taken through the skin instead of the lungs this winterlong kind of sleep is called hibernation it lasts till spring other amphibians such as salamanders and NES hibernate in protected places on land so hibernation is another characteristic that all amphibian share we've seen that all amphibians begin their lives in water equipped with gilds those that undergo metamorphosis spend part or the rest of their lives on land we learn that even on land amphibians live in damp places near water some amphibians like the mud puppy never lose their gills and spend all their lives in the water in spite of many differences all amphibians have the same general structure whether they have tails or not all amphibians have backbones and belong to that family of animals called vertebrates they are the only animals with backbones that go through distinct stages of development or change the change is called metamorphosis they are creatures well fitted to live both on land and in water and that's why they're called amphibians [Music]