Amphibians.

Presentation on theme: "Amphibians."— Presentation transcript:

1 Amphibians

2 Evolution of Amphibians

3 "Amphibian" comes from the Greek meaning "both life"
"Amphibian" comes from the Greek meaning "both life". Amphibians can live on water and on land. Scientist infer that amphibians evolved from lobe-finned fishes called crossopterygians.

4 Crossopterygian

5 Biologist conclude that amphibians appeared during the late Devonian period, about 345 million years ago.

6 Crossopterygians had no gills but they had internal nostrils and a primitive lung that may have enabled them then to respire for periods of time on land.

7 Characteristics of Amphibians

8 Amphibians are cold-blooded, which means their blood temperature rises and falls with that of the surrounding environment •

9 They use gills, lungs, skin, and mouth cavity in respiration.

10 They have moist, smooth, thin skin with no scales
They have moist, smooth, thin skin with no scales.Feet are webbed and the toes lack claws.

11 Amphibians have many prominent characteristics that are adaptations to a life spent both on land and in water: They change from an aquatic larval stage to a terrestrial adult form. This transformation is called metamorphosis

12 Amphibians enter a state of dormancy or torpor when conditions are unfavorable. They often bury themselves in mud or leaves, emerging when conditions are better.

13 Such states of inactivity are known as known as:
Hibernation when it occurs in the winter Estivation when it occurs in the summer

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Larvae have two-chambered hearts; adults have three-chambered hearts and well-developed circulation. Copyright Cmassengale

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Eggs lack multicellular membranes or shells. They are usually laid in water or in a moist environment and fertilized externally. Copyright Cmassengale

16 Classification of Amphibians
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Biologists have identified about 2,375 living species of amphibians and have classified them into four orders Anura – Frogs & Toads Urodela – Salamanders Trachystoma – Mud eels Apoda - Caecillians Copyright Cmassengale

18 Frogs and toads make up the Order Anura ("without a tail").
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Salamanders and other amphibians with legs and tails make up the Order Urodela ("visible tail"). Copyright Cmassengale

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. Some aquatic amphibians (mud eels & sirens) belong to the Order Trachystoma ("rough mouth") Copyright Cmassengale

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Siren Copyright Cmassengale

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Apoda includes caecilians, a tropical, burrowing worm-like amphibians that is often Legless Copyright Cmassengale

24 Anuran Characteristics
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Frogs and toads comprise the order Anura There are about 3,500 known species of frogs and 300 kinds of toads They are found on every continent except Antarctica Copyright Cmassengale

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Some types spend their entire life in or near water, but others live mainly on land and come to the water only to mate Copyright Cmassengale

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Some frogs and toads are climbers that dwell in trees or burrowers that live underground. Copyright Cmassengale

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Toads and frogs have many similarities in the way they look. Some basic differences between them are: toads have dry, warty skin, while frogs have smooth, wet skin. Copyright Cmassengale

29 Both frogs and toads return to water to reproduce
Both frogs and toads return to water to reproduce. In nearly all species eggs are fertilized externally. The fertilized eggs hatch into swimming larval forms called tadpoles

30 Urodelan Characteristics

31 Salamanders, typical members of the Order Urodela, have elongated bodies, long tails, and smooth, moist skin

32 Compared to the anurans, salamanders are less able to remain on dry land, although some can live in dry areas by remaining inactive during the day

33 Salamander lay their eggs in water and like anurans they hatch into swimming larva
Salamander eggs

34 Other species can reproduce in damp land environments
Other species can reproduce in damp land environments. Eggs laid on land hatch into miniature adult salamanders Marbled Salamander

35 Apodan Characteristics

36 Caecilians, members of the Order Apoda, compose a highly specialized group of tropical burrowing amphibians

37 These legless wormlike creatures average 30 cm long, but they can be up to 1.3m long.
They have very small eyes and are often blind. They eat worms and other invertebrates

38 The caecilian male deposits sperm directly into the female, and the female bears live young

39 Trachystoma Characteristics

40 The Order Trachystoma contains three living species of mud eels, or sirens.
Sirens live in the eastern United States and north­eastern Mexico.