Amphibian Lecture Anatomy of Amphibians

Necturus maculosus

Order Apoda

Order Caudata

Order Anura

General Amphibian Traits

• Tetrapods

• Skeleton mostly bone

• 3-5 digits on forelimb (most 4) / 5 digits on hind limb

• 3 chambered heart – 2 atria and 1 ventricle

• No dermal scales

• Skin moist and glandular

• Most with indirect development, some with tadpole

larvae

• Gills as larvae/juveniles, lungs present but may

degenerate, some with dermal respiration

POST-NOTE THOUGHTS

What obstacles did amphibians

face when moving onto land?

Generate some thoughts

The initial problems…….

1. Widely fluctuating temperature (air)

2. Loss buoyancy - time to deal with

gravity

3. Need to conserve water, different

nitrogenous waste

More problems….

4. Water tight skin

5. Reproductive problems eggs need to be placed somewhere they won’t be disturbed

6. Sensory receptor issues eyes need to deal with longer distances

7. Ears need to hear higher frequencies

POST-NOTE THOUGHTS

General Anatomy Highlights….

• THE SKIN:

• Two layers epidermis and dermis

• Specialized structures:

GLANDS (found in the epidermis)

– Mucous gland: secrete a clear, slimy, mucus

that maintains a thin film over the outside of the

skin

– Granular gland: Concentrated on the head

Produces a poison, toxic to predators

– https://www.youtube.com/watch?v=Ce8a5bFQexA Waxy Money

Frog

Coloration of the Skin

• Pigment cells chromatophores

– Melanophores: black or brown

– Iridophores: white or reflective

– Xanthophores: yellow, orange, red

• Combination of the above produce the

outside color of the skin we see

The Skin Continued• The skin has a major

role in: Osmoregulation

and Thermoregulation

• The skin is highly

vascular, has a high

surface area, and is a

major source of gas

exchange.

Cutaneous respiration -oxygen is

absorbed directly into the bloodstream

then veins and arteries carry it to and

from the heart.

POST-NOTE THOUGHTS

Animal Decline

• https://www.youtube.com/watch?v=Bvidpa

pF1bg

• Hank Green 4:14

Ears• Ears: Hearing -reception of sound and

helps maintain balance

• Hearing is important:

• 1. attract a mate

• 2. intimidate

• 3. encounter call (GET OFF ME!)

• 4. Distress call » https://www.youtube.com/watch?v=1oTBHH_LxDI

• Lateral Line System Present

EyesLaterally placed

Rods and Cones

Terrestrial and arboreal Large Eyes

Fossorial- relating to burrowing or living

underground / little to no eyes

Upper eyelid is fixed

Lower lid called nictitating membrane (protects

and moistens)

Nasal Organs

• Nose used in chemoreception

• Jacobson’s organ an olfactory sense

organ, allows organism to perceive

pheromones, or chemical messages, from

other animals of the same species.

POST-NOTE THOUGHTS

Circulatory System and Respiration

• Three chambered heart: 2 atria, 1 ventricle

• Lungs

– Main function – breathing

– aid in vocalization (voice box)

– Highly vascular, thin wall, large surface area

• Gills found in larvae stage

Changes in Vertebrate Circulatory Systems

Amphibian Heart Anatomy

Amphibian Respiration

• https://www.youtube.com/watch?v=Nfojq4ikHH0

• 3:28

POST-NOTE THOUGHTS

Digestion

• Not too crazy, one end

is in, the other is out.

• Carnivores, have teeth

• Large intestines (new

structure)

Urinary and Reproductive Systems

• Kidney- regulate salt and water balance

• (same structure)

• Gonads Testes and ovaries very different

• Frogs will lay eggs and ‘gelatinous’ mass

• External fertilization

• Amplexushttps://www.youtube.com/wa

tch?v=fzI_yaY_j-Q

Vernal Pools spring to Life

Specialized behaviors:

• Autonomy-self

induced loss of a

body part

– Salamanders can

grow parts back!

– Not everyone can do

this!

http://www.youtube.com/watch?v=EsCSwVx3GvA

(2:17)

Order Gymnophiona (Apoda)

Caecilians

• Legless

• Burrowing or aquatic

• Tropical

• Internal fertilization

• Oviparous & viviparous

species

• Direct development in

most• http://www.youtube.com/watch?v=DMvL4zOLSeM&lis

t=PL095BCEEEF27D59CE

Order Caudata (Urodela)

• AKA Salamanders

• Have a tail

• Divergence in respiratory

mechanisms

• Paedomorphosis prevalent

• Internal fertilization

Salamander/Newt Lifecycle

Order Anura• Frogs & Toads

• No tail

• External

fertilization

• Indirect

development

in most

https://www.youtube.com/watch?

v=v9GzuB0iCfI

3 min (Exception to indirect)

Frog or Toad?• Frogs

– Associated with

more aquatic

habitats

• Toads

– Thicker skins

– Dryer habitats

Metamorphosis• Shift from an aquatic

embryonic stage to a terrestrial

stage and maturation/growth.

• Dramatic in FROGS.

• Change in skin structure, loss

of lateral line, lungs develop,

behavior changes, feeding

changes, locomotion changes,

physiological changes.

Typical Anuran Lifecycle

Transitional Forms

Early Land Tetrapods