NOTES - Amphibians · – Infected amphibians ‘ behavior changes which include lethargy, failure...
Transcript of NOTES - Amphibians · – Infected amphibians ‘ behavior changes which include lethargy, failure...
Amphibians
What are Amphibians?• Amphi = both sides;
bios = life (double life)– Have 2 stages of life
(metamorphosis) • Juveniles are water -
breathing organisms• Adults are air-breathing
organisms• Some adults will retain
their juvenile life features
General Characteristics• Tetrapods• Vertebrates• Thin, moist, glandular skin• No dermal scales• Ectotherms (control body temperature from
outside means)• Skeleton mostly bone• 3-5 digits on forelimb (most 4)/ 5 digits on
hind limbs
Distribution
• Amphibians are found all over the world – Due to their ectothermy, most species found
in warm regions
Distribution• In areas that get too cold or too hot during
portions of the year, amphibians will become dormant– Lowering metabolism– In water, will “hibernate” in oxygen rich waters– On land, burrow in ground or hide in cracks of
trees– Some frogs have antifreeze – In hot areas, some frogs can create
waterproof cocoons
Integument (skin)
• Has major role in – Osmoregulation: regulation of water and
solutes within body– Thermoregulation: regulation of body
temperature• Is highly vascularize, high surface area,
allows gas exchange
Integument (skin)• Contains a variety of
glands:– Mucous glands: make skin
slippery, hard for predators to grasp
– Poison glands: usually behind eyes, produces toxins
• Contains chromatophores: provides skin its color for warning, camouflage, mates
Reproduction• Most amphibians need water
for a portion of life cycle (can vary depending on species)– External reproduction
(females lay eggs, males fertilize eggs)
– Eggs are laid in water, then tadpoles (larva) hatch
– Tadpole have a small mouth, no legs, gills, and tail
• herbivores
Reproduction– Metamorphisis
• Begins with development of hind legs , then front legs
• lungs begin to develop causing the tadpole to go to surface of water for oxygen
• Intestine shorten to accommodate carnivorous diet• Eyes migrate rostrally and dorsally
Circulation• Have a 3-chambered heart
but oxygen-rich and oxygen-poor blood tend to mix
• Have lungs but no muscles to breathe– Inhale by swallowing
• Many amphibians depend on gas exchange through skin– Skin is moist to help with gas
exchange
Why Study Amphibians?
• Indicator Species– Very sensitive to climate change and pollution
• 6,300 known species around the world– 32% of the species are considered threatened
• In the past 2 decades, – 168 species have gone extinct– 42% of the populations are declining rapidly
• https://www.youtube.com/watch?v=BvidpapF1bg
Reasons for Decline• Major reason for decline is habitat destruction• Chytridiomycosis (Chytrid)
– Fungus that causes ventral portion of skin to redden, skin to slough off, ulcers, etc…
– Infected amphibians ‘ behavior changes which include lethargy, failure to seek shelter or flee, among many others
• Climate change – Increase UV-B rays
• Introduced species• Over-exploitation
Ways to Monitor Amphibians
• Depends on the species• A few methods include:
– Cover boards– Pitfalls– Searching through surface
debris or streams– Calling Surveys
3 Orders of Amphibians• Caudata
– Includes salamanders and newts
– Have a tail– Divergence in respiratory
system– Paedomorphosis prevalent:
retention of juvenile or larval stage
– Internal fertilization
3 Orders of Amphibians
• Anura– Includes frogs and toads– No tail– External fertilization– Indirect development in
most (radical body change)
3 Orders of Amphibians
• Apoda (without legs)– Includes caecilians– Legless– Burrowing or aquatic– Tropical– Internal fertilization– Direct development
in most
What species will we see?• Dunne’s Salamander• Long-toed Salamander• Pacific Giant Salamander• Torrent Salamanders• Western Red Backed Salamander• Red-legged Frog• Ensatina• Rough-skinned Newt• Tailed Frog
Dunne’s Salamander
Long-toed Salamander
Pacific Giant Salamander
Torrent Salamander
Northwestern Salamander
Western Red-backed Salamander
Ensantina
Rough-skinned Newt
Red-legged Frog
Tailed Frog
Pacific Tree frog
Bullfrog