Presentation on theme: "Urodele & Gymnophiona General Amphibian Characteristics Salamanders"— Presentation transcript:
1Urodele & Gymnophiona General Amphibian Characteristics Salamanders Ecological Role of SalamandersDiverse Life HistoriesCourtshipVariation among larval salamandersDefensive behaviorGymnophiona – Caecilians
2I. General Amphibian characteristics: EctothermsFour limbsTwo occipital condyles
3Salamanders - Urodela (Caudata) A. Characteristics4 limbed animalsTrunk superficially segmentedSize varies from 30mm to 2mrather have an opercular apparatus
4the Salamanders~515 species, 24 Genera, 9 Families (8.5% of all amphibians)-date back to middle Jurassic
6B. Ecological Role of Salamanders: Play role in organizing communitiesMole salamander larvae influence abundance and diversity of invertebrates in vernal pondsGiant salamanders reach high densities & biomass in small streams lacking fish
7Diverse Life Histories: Many species have biphasic life cyclePaedomorphesisSome deviate and retain the larval form, particularly where the terrestrial habitat is unfavorable for survival
8Biphasic lifestyleAdult Form (Ambystoma)Larval form
10C. CourtshipWell-defined breeding season (usually triggered by seasonal changes)Courtship/mating behavior:Male spermatophore & internal fertilizationspermatophores vary in size, shape & composition – most consist of a gelatinous base that tapers toward the top & supports an apical sperm massmale 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 topExternal fertilizationPheromones –
19Salamander 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.
20Terrestrial Salamanders Active at night on ground surfaceUsually restrict activity to moist microhabitats,Dry conditions =Territorial =
21Plethodon cinereus – Red backed Salamander Adults mark territories
22E. 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.
24Known from the early Jurassic – Earliest fossil = Eocacilia (had limbs)
25Gymnophiona: 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 developmentTyphlonectidae.-- 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.
27Characteristics of Caecilians Occur worldwide in the tropics & look like earthworms…Annulated bodies =Tail is very short or absentTeeth are curved and relatively long compared to other amphibiansChemosensory structure (tentacle)
28Characteristics cont.Skull is very solid, with extensive suturing of cranial elements,Operculum absent (no ear openings)Dermal scales often presentAll caecilians have internal fertilizationMales –Offspring may develop internally or externally