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