1. Urodele & Gymnophiona General Amphibian Characteristics Salamanders
Ecological Role of Salamanders
Diverse Life Histories
Courtship
Variation among larval salamanders
Defensive behavior
Gymnophiona – Caecilians

2. I. General Amphibian characteristics:
Ectotherms
Four limbs
Two occipital condyles

3. Salamanders - Urodela (Caudata)
A. Characteristics
4 limbed animals
Trunk superficially segmented
Size varies from 30mm to 2m
rather have an opercular apparatus

4. the Salamanders
~515 species, 24 Genera, 9 Families (8.5% of all amphibians)
-date back to middle Jurassic

5. Chinese giant salamander (Andrias davidianus)
Hemidactylium scutatum
Del Norte Salamander (Plethodon elongatus)

6. B. Ecological Role of Salamanders:
Play role in organizing communities
Mole salamander larvae influence abundance and diversity of invertebrates in vernal ponds
Giant salamanders reach high densities & biomass in small streams lacking fish

7. Diverse Life Histories:
Many species have biphasic life cycle
Paedomorphesis
Some deviate and retain the larval form, particularly where the terrestrial habitat is unfavorable for survival

8. Biphasic lifestyle
Adult Form (Ambystoma)
Larval form

9. Ambistoma mexicanum (Axolotl)
Paedomorphic!

10. C. Courtship
Well-defined breeding season (usually triggered by seasonal changes)
Courtship/mating behavior:
Male spermatophore & internal fertilization
spermatophores vary in size, shape & composition – most consist of a gelatinous base that tapers toward the top & supports an apical sperm mass
male deposits one or more in front of a female, the female then moves forward, aligns her vent above the spermatophore and removes all or a portion of the sperm mass from the top
External fertilization
Pheromones –

15. D. Variation among larval salamanders:
Morphological adaptations that correlate with their environment
“pond-type” –
“stream-type” –

17. Larval Salamanders (cont.)
Predators of aquatic invertebrates, some cannibalistic or feed on heterospecific larvae
Vernal ponds =
Streams =

18. Ambystoma maculatum
Pseudotriton ruber

19. Salamander Migration:
On rainy nights, Marbled salamanders (Ambystoma opacum) emerge from their hiding places beneath leaves and logs, traveling to low-lying areas that will become pools when they are soaked with spring rains, to lay their eggs; in the spring, aquatic larva hatch from the eggs and develop into salamanders.

20. Terrestrial Salamanders
Active at night on ground surface
Usually restrict activity to moist microhabitats,
Dry conditions =
Territorial =

21. Plethodon cinereus – Red backed Salamander
Adults mark territories

22. E. Defensive Behavior: Posturing Toxins Aposmatic coloration
Defensive posture the cave salamander (Eurycea lucifuga) assumes when attacked by a predator such as a bird. Note that the salamander closes its eyes and raises and wiggles its tail above its lower head.

23. III. Gymnophiona - Caecilians

24. Known from the early Jurassic –
Earliest fossil = Eocacilia (had limbs)

25. Gymnophiona: 6 Families, 160 species
Caeciliaidae.--is the largest family, with about 22 genera in Mexico, Central and South America, subsaharan Africa, India, SE Asia and the Seychelles. Many are small, but the largest reach 1.5 m. Some are viviparous; others have direct development
Typhlonectidae.-- are truly aquatic caecilians, with four genera in South America, some to 75 cm. The posterior body is laterally compressed, and there is no tail. They are also viviparous.

27. Characteristics of Caecilians
Occur worldwide in the tropics & look like earthworms…
Annulated bodies =
Tail is very short or absent
Teeth are curved and relatively long compared to other amphibians
Chemosensory structure (tentacle)

28. Characteristics cont.
Skull is very solid, with extensive suturing of cranial elements,
Operculum absent (no ear openings)
Dermal scales often present
All caecilians have internal fertilization
Males –
Offspring may develop internally or externally

29. Cloaca