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Lecture

[14.2] Amphibians

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Department
Biology
Course
BIOL 2030
Professor
Scott Kelly
Semester
Fall

Description
Amphibians Amphibia Vertebrate class including the extant subclass Lissamphibia, comprising the frogs and toads (order Anura), newts and salamanders (order Urodela) and the worm-like caecilians (order Apoda). There are also a number of extinct subclasses dating from the Devonian onwards, of which the ichthyostegalians are the earliest amphibian fossils found. Amphibians are ectothermic anamniote tetrapod vertebrates that typically return to the water for reproduction and pass through an aquatic larval stage with gills. Adults generally have lungs, are carnivorous, and may be at least partly land-living,a nd modern amphibians have a moist skin without scales, which is permeable to water and gasses Anura One of the three orders of extant amphibians, comprising the frogs and toads Buccal Pumping Using lungs with a positive-pressure breathing (push air in) Caudata =Urodela; One of the three orders of extant amphibians, containing the newts and salamanders, amphibians with well-developed tails and two pairs of more-or-less equal legs Clavicle Collar bone, forming anterior or ventral portion of the shoulder girdle Granular Gland Gymnophiona Apoda; Order of limbless burrowing amphibians, commonly known as caecilians, having a reduced or absent larval stage and minute calcified scales in the skin Humerus The bone of the upper arm, or upper part of vertebrate forelimb Integument Covering, investing, or coating structure or layer Mucus Gland Slimy material rich in glycoproteins, secreted by these cells Paedomorphosis Retention of juvenile traits in adults Pectoral Girdle In vertebrates, a skeletal support in the shoulder region for attachment of fore-fins or forelimbs, made up of a hoop of cartilages or bones, usually the scapula, clavicle, and coracoid Perennibranchiate Having gills persisting throughout life, as in certain amphibians Phalanges The bones of the fingers and toes of vertebrates Radius Bone of vertebrate forelimb between humerus and carpals Sacculation The formation of sacs or saccules (small sac/pouch) Scapula In vertebrates, the shoulder blade (the dorsal parto f pectoral girdle) Stratum Corneum Cornified layer Ulna One of thelong bones of vertebrate forearm, parallel with radius and in some vertebrates combined with it to form a single bone Ulnare One of the wrist bones, lying at the far end of the ulna Viviparity Giving birth to live young Amphibia Orders  Gymnophona (caecilians) burrowing organisms; males copulatory organ  Caudata (salmanders/newts) Northern region; Chinese GIANT Salamander (up to 6 ft long) o In freshwater, & predators as larvae & adult  Anura (frogs/toads) many variations, & CAN TOLERATE FREEZING o Many variations of fundamental life cycle; many habitats; vocalization for communication; Body plan heavily mod from ancestral (4 same limbs, prominent tail) Early Evolution (400 mya, invasion had begun)  @ Devonian era, mild temp & alternating droughts/floods  unstable aq. Environment o 1) Lungs (aerial breathing, aid survival) gills bad for gas Xch (in air)  Dev. as outgrowth of foregut (efficiency by sacculation -alveoli, increase SA- & vascularization of gas-filled space)  Modern Lungfish fundamental plan (Note: swimbladder COMPLTELY SMOOTH, not 4 gas X)  Note: upon invasion, gills must be given up for lungs (else dry out) o 2) Limbs fin shape (& appendicular skeleton)  use to reach out for air Tetrapod Limb Development: NOTE “life evo’d for life in water, not for life in a
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