1. AMPHIBIANS The Rise of Amphibians (Devonian Period)
360 MYA – Carboniferous period
Tetrapod limbs – shoulder/hip girdle – walking on land
Lungs for breathing air

2. AMPHIBIANS Scientific classification
Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata Class: Amphibia

3. AMPHIBIANS Orders of Amphibia
 Anura- w/out tail – frogs/toads 5,296 species   Caudata- with tail – salamanders/newts 555 species   Gymnophiona –caecilians- naked snake 171 species

4. AMPHIBIANS Life on land presented new challenges
Reason for movement to land –
By late Devonian period
Climate change caused extinction of many ocean animals and decreased oxygen availability as a result less food available so animals invaded land

6. Devonian Period

7. Carboniferous period

8. a drier habitat
Varied food sources
Egg laying still required water

9. Legs - Tetrapod
Their circulatory systems became more efficient allowing for more activities.

10. Tetrapod – 4 for land

12. AMPHIBIANS Water availability was not reliable.
Air temperatures and climate was more variable

13. AMPHIBIANS New habitats, including vast arrays of
plants, insects, necessitated keener
sensory (vision, hearing, balance) input.
As a result, different regions of the brain
further developed.

15. AMPHIBIANS
The word ‘amphibian’ comes from the Greek meaning, “both” (amphi), and bios, meaning, “life”.

16. ectothermic
When we say, ‘cold-blooded’ we mean that the amphibians do not hold or regulate their own body temperature.
Their internal body temperature depends on the external environment. They must absorb the warmth of the sun or become sluggish at very cold temperature to maintain bodily heat.

17. AMPHIBIANS
FROG TOAD SALAMANDER

18. AMPHIBIANS
NEWTS CAECILIANS

19. AMPHIBIANS Most amphibians share 5 key characteristics:
1. Legs – adapted to living on land (frogs, toads, salamanders, newts all have 4 legs)
2. Lungs – larval amphibians have gills, most
adult amphibians breathe with a pair of lungs (salamanders are an exception)

20. AMPHIBIANS
3. Double-loop circulation – two large veins called Pulmonary veins return oxygen-rich blood from the lungs to the heart. Oxygen-rich blood is then pumped to the tissues.
4. Partially divided heart – the atrium of the heart is divided into left and right sides, but the ventricle is not. A mixture of oxygen- rich and oxygen-poor blood is delivered to the tissues.

21. AMPHIBIANS
5. Cutaneous respiration - besides breathing with their lungs, amphibians take up oxygen through their skin.
The skin is usually thin and some-
times supplied with glands that
produce toxins.

22. REPTILES & AMPHIBIANS
Double-loop circulation in amphibians:

23. AMPHIBIANS Life Cycle ‘Metamorphosis” of a
Tadpoles - herbivores – adult carnivore

24. AMPHIBIANS Frogs and Toads 1. long hind limbs with powerful muscles
allow them to leap into the air.
2. success on land is due in part
to: the excellent prey-grasping
capability of the tongue attached to the
front of the mouth.

25. AMPHIBIANS 3. Frog skin has mucous glands, poison
glands & antibiotics that provide
protection against pathogens in an
aquatic habitat.
4. Scientists have noticed frog populations
on the decline due to increases in
parasitic attacks, predation, UV
radiation, habitat losses & chemical
pollution. Environmental barometer

26. AMPHIBIANS Frog versus Toad Frog has two bulging eyes
strong, long, webbed hind feet that are adapted for leaping and swimming
smooth or slimy skin (generally, frogs tend to like moister environments)
Frogs tend to lay eggs in clusters.

27. AMPHIBIANS Frogs versus Toads
Toads have stubby bodies with short hind legs (for walking instead of hopping)
warty and dry skin (usually preferring dryer climates)
paratoid (or poison) glands behind the eyes
The chest cartilage of toads is different.
Toads tend to lay eggs in long chains.

28. REPTILES & AMPHIBIANS Salamanders
1. Live in temperate zones & in tropical
areas of Central and South America
numbering
2. When they walk, the body bends from
side to side, much like a fish moving
through water.

29. AMPHIBIANS 3. Adults may retain larval features including
gills and tail.
4. Some larvae may become sexually mature
but not reach a true adult stage
5. Both forms, larval & adult, are carnivorous.

30. AMPHIBIANS Caecilians
1. As amphibians evolved they lost their limbs & vision, but not their prey-capturing jaws.
2. These unusual creatures live burrowed
in the forest floor where they hunt for
invertebrate prey.
3. Most species burrow through the soil,
using touch & smell to pursue insects & earthworms. The few aquatic types use electrical cues.