Amphibians PART II VERTEBRATE ZOOLOGY (VZ Lecture13 – Fall 2012 Althoff - reference PJH Chapter 10)

Classification of Amphibia CLASS Amphibia SUBCLASS Labryinthodonotia* Leposondyl* Lissamphibia ORDER Urodela Anura Gymnophiona * = extinct (salamanders) (frogs) (caecilians)

Focus on Frogs ORDER: ________ ( Greek: “ an ” = without, “ uro ”= tail ) 29 familes, ~4,800 species (compare to 10 families, ~515 species for salamanders) Found on all continents except Antarctica Body form is more compact, clearly specialized for jumping. Jumping aided by hind limb-muscle arrangement form lever-like action that can catapult them into the air a) powerful pelvis b) pelvis strongly fastened to vertebral column c) posterior vertebrate fused into solid rod forming ___________ d) hind legs elongate, tibia and fibula fused

Triassic fossil PRIMITIVEModern day DERIVED 1 1a 2 2a 3 3a 4 4a

Primitive vs. Derived Skeletal Characters  Reduction number of toes on front feet  Reduction in presacral vertebrae  Pelvic girdle changes  Hind limbs & toes 5 14 short ilium, no urostyle short

Closer look at “rear” end “adjustments” Hind legs elongate, ____________________ = 1 bone Stronger attachment of a stronger, __________ ________ to the vertebral column _________ (part of pelvis) is elongate and reaches far anteriorly. Urostyle (part of pelvis) is what was vertebrae— now all fused into a solid rod

Closer look at “midway” adjustments Reduction in number of ____________ vertebrae Presacral vertebrae are strongly braced by _________________ that restrict lateral bending

Closer look at “frontend” adjustments ________ forelimbs ________ pectoral girdle Goliath frog

Eye Structure & Placement Large Placed well forward on the head Result  __________________

Specialization of Locomotor Systems Fig p231 PJH HINDLIMB LENGTH (longer) FORELIMB LENGTH (longer) walker-hopper walker-jumper jumper hopper-burrower walker-hopper-burrower hopper swimmer

Frog Natural History & Locomotion ________-legged species that move by hopping frequently are wide-ranging predators a) more vulnerable to predators b) shorter legs prevent rapid escape c) result  most have potent defensive chemical released from glands in skin when attacked ________-legged species that move by jumping usually are sedentary predators (“ambush” predators) a) cryptically colored b) usually lack chemical defenses c) result  escape w/ rapid series of leaps

Webbing & Toe Specializations _______________ species have webbed feet vs. Most _____________ based frogs (including those referred to as toads) usually have little webbing between the toes Spadefoot toads (NA) have keratinized structure on hindfoot that aids digging backward into the soil

Tree Frog Toe Surfaces Many tree frogs have enlarged toe disks a) epidermal layer has peg-like projections which has mucus gland that secretes a viscous solution b) canals in between c) result  ____________ & __________ hold toe pad and surface together Fig p233 PJH

Toe Disks – Found in Several Lineages Toe disks are not a “tree frog” exclusive…some terrestrial species (vs. the “arboreal” tree frog species) also have expanded toe disks Toe disks have evolved independently in several lineages….a specific example of convergence in structure. This, in a more general sense, is known as _____________________ which…. Bottomline: diversity in structure and form among anurans is considerable if one looks at the finer points! …… is the process whereby organisms not closely related (not monophyletic), independently evolve similar traits as a result of having to adapt to similar environments or ecological niches

Ohio – 4 families represented Family Pelobatidae - ___________________ 1 species – southeast Ohio…____________ _____________________ eastern spadefoot

Ohio – 4 families represented Family Bufonidae - ___________________ 2 species in Ohio eastern American toad

Ohio – 4 families represented Family Hylidae - ___________________ 6 species in Ohio gray tree frog

Ohio – 4 families represented Family Ranidae - _____________________ 6 species in Ohio pickerel frog