Amphibians were the first vertebrates to adapt to living on land, though most still require water for reproduction or parts of their life cycle. They have moist skin, minimal teeth, and undergo metamorphosis from aquatic tadpoles to terrestrial adults. While tadpoles are herbivorous, most adult amphibians are carnivorous. They have complex life cycles and come in three main types: anures without tails, urodels with tails, and legless gymnophions.

1. Amphibians
Damnjanović Ivana

2. Evolution

3. Evolution

4. Evolution

Of the living vertebrates, amphibians were the first to
adapt to extended periods of time on land.

Most still need fresh water at some point in life cycle.

These multiple habitat requirements are reflected in the
complex life cycle of most (but not all) species.

6. Evolution

7. The Complex Life Cycle

8. Types

Anures (without tail)

Urodels (with tail)

Gymnophions (without
legs)

9. General Characteristics

Have no nails or claws

Minimal number of teeth

Most have a tongue that is projectile and
sticky

Spends first stages of life in water as tadpoles

They go through drastic changes during
development (caused by changes in
hormones)

Tadpoles are herbivorous while adults are
carnivorous

10. 
They are ectotherms

During extreme environmental conditions they
either hibernate (winter) or aestivate (summer).

11. Skin

Smooth, moist skin

Mucous glands (prevent desiccation /
slippery / disease-free)

Poison glands:
- Produce diverse array
of chemicals
Epibatidine
(dart-poison frogs)
Lipid-soluble Alkaloid
(Blocks Ach receptors)
Non-addictive
painkiller

12. 
Pigment cells (colour)

15. Respiration

Cutaneous – Gas exchange occurs across moist skin

Pulmonary – Gas exchange occurs in paired lungs (too small
for all gas exchange)

Gills – Larval forms and neotenics (neoteny = adults that
retain juvenile characteristics)

16. Feeding

Tadpoles are herbivorous while
adults are carnivorous

18. Blood system

Heart: 2 atriums and 1 ventricle

19. Nervous, sensory and muscular system

Well developed brain attached to the dorsal nerve cord.

They contain a well developed muscular system.

Sensory receptors located all over the skin

Good vision since these animals are mainly vision
feeders; that is, they have to use their sight to find and
capture food.

20. Excretion

21. Reproduction

22. Reproduction

External fertilization in moist environments.

Exceptions to the external fertilization are salamanders (only
about 10% are external).

Jelly-like eggs need to be laid in water.

Their offspring develop through a process called
metamorphosis.

23. Vocalization

Sound production is primarily a reproductive function of
male anurans.

These calls attract females to breeding areas and to
announce to other males that a given territory is occupied.

These calls may also cause some hormonal changes internally
to occur.

Sounds are caused by air being forced from the lungs over
the vocal cords and cartilages of the larynx, causing them to
vibrate.

26. Anura

27. Anura

No tail

External fertilization

Indirect development
in most

28. Urodela

29. 29
Caudata (Urodela)

Have a tail

Divergence in respiratory
mechanisms

Internal fertilization
Ambystoma mexicanum
(Axolotl)

30. 30

31. Gymnophiona

32. 32
Gymnophiona

Legless

Burrowing or aquatic

Tropical

Internal fertilization

Oviparous & viviparous species