Amphibian Lecture Anatomy of Amphibians Order Apoda Order Anura Necturus maculosus Order Caudata
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
Laterally placed Rods and Cones Eyes 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 Amplexus https://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
AKA Salamanders Have a tail Order Caudata (Urodela) Divergence in respiratory mechanisms Paedomorphosis prevalent Internal fertilization
Salamander/Newt Lifecycle
Frogs & Toads No tail External fertilization Indirect development in most Order Anura 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