Amphibian Lecture I Lecture.pdf · General Amphibian Traits •Tetrapods •Skeleton mostly bone...
Transcript of Amphibian Lecture I Lecture.pdf · General Amphibian Traits •Tetrapods •Skeleton mostly bone...
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