BIOL-2116 - Amphibians 17
Page 1: Introduction to Amphibians
Overview of amphibia focusing on habitats and lifestyle
Importance of newt habitats in ecosystem balance
Page 2: Information Sources
Chapters covered:
Modern Amphibians 17.2
Caecilians 17.3
Salamanders 17.4
Frogs & Toads 17.5
Page 3: Main Sections
Shared Amphibian Traits
Major Clades & Diversity
Conservation
Page 4: Lissamphibian Clade
Hickman et al. 2020 highlights over 7900 species within Lissamphibian clade.
Temnospondyls survived the Paleozoic period.
Amphibians categorized as Non-amniotes.
Page 5: Shared Traits of Amphibians
Typically inhabit freshwater environments.
Life cycle involves a transition from aquatic larval to terrestrial adult form.
Ectothermic: Unable to regulate body temperature internally.
Adults are carnivorous and have specialized organs to sense the thermal environment.
Page 6: Skin Characteristics
Amphibians have smooth, thin, moist skin for respiratory purposes.
Skin facilitates gas exchange, in some species is the sole respiratory surface.
Important structures in the skin:
Mucous glands for moisture
Poison glands for protection
Pigmentation for camouflage
Page 7: Reproductive Traits
Amphibians depend on water bodies due to anamniotic eggs (non-shelled eggs).
Larval stages are aquatic and initially breathe via gills.
Lungs develop but become functional post-metamorphosis, relying initially on yolk for nutrition.
Page 8: Shared Amphibian Traits Reviewed
Key characteristics outlined previously.
Page 9: Amphibian Diversity
Global distribution except in Antarctica, limited by freshwater habitat reliance.
Three major orders:
Salamanders (Urodela)
Caecilians (Gymnophiona)
Frogs and Toads (Anura)
Page 10: Order Urodela
Known as tailed amphibians: over 700 species in moist regions.
Typical body size: smaller than frogs.
Example: Four species found in Manitoba: three terrestrial and one aquatic.
Page 11: Salamander Locomotion
Salamanders exhibit an ancestral body plan, allowing a unique sequential gait similar to fish swimming.
Movement involves alternating muscle contractions.
Page 12: Reproduction & Life Cycles
Internal fertilization is common, lacking a direct copulatory organ.
Typical life cycle: aquatic larval stage followed by terrestrial adults (oviparous).
Page 13: Developmental Variations
Species exhibiting facultative metamorphosis may remain sexually active in both larval and adult forms.
Paedomorphism observed in some, retaining juvenile characteristics throughout life.
Page 14: Order Gymnophiona
Smallest amphibian group (~200 species) with elongated bodies and no limbs; fossorial lifestyle.
Primarily found in tropical habitats.
Page 15: Gymnophiona Reproduction
Utilize internal insemination.
Both oviparous and viviparous species present; some nourish young through ectodermal growth.
Page 16: Order Anura
Most diverse group with ~6700 species; adults lack tails.
Diverse body morphological adaptations for effective locomotion (jumping).
Page 17: Feeding Mechanisms
Frogs possess flat skulls and large mouths for predation.
Highly flexible diet: consume various organisms, including other amphibians.
Sticky tongues aid in capturing prey, muscular contractions assist in swallowing.
Page 18: Skeletal Adaptations
Skeleton specializes for jumping.
Hindlimbs elongated for leverage; pelvic reinforced for shock absorption.
Page 19: Function and Structure
Webbing between hind legs enhances movement efficiency.
Page 20: Frog and Toad Families
54 families worldwide; 3 prominent families in North America:
Ranidae: true frogs
Hylidae: tree frogs
Bufonidae: true toads
Page 21: Overwintering Strategies
Species in temperate regions must manage temperature fluctuations.
Two approaches: dormancy and freezing.
Glucose aids in cell preservation during freezing.
Page 22: Reproductive Strategies
Vocalization used for female attraction.
External fertilization occurs during amplexus; mostly oviparous with some exhibiting parental care.
Page 23: Conclusion
Shared Amphibian Traits
Major Clades & Diversity
Conservation efforts discussed
Page 24: Threats to Amphibians
Habitat loss is a primary threat, along with climate change and water pollution.
Page 25: Chytrid Fungus Impact
Causes chytridiomycosis, debilitating many amphibian species.
Origin traced to Asia, now widespread across continents.