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orders of class amphibia
- Caudata: salimanders
- Anura: frogs
- Gymnophiona: (caecilians which are limbless, burrowing and almost blind)
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orders of class reptilia
- Testudina: turtels
- Crocadylia: crocs gravials caimans, and alligators)
- Sphenodontida: the tuatara
- Squamata: lixards and snakes
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Integument amphibia
- frogs have thin skin with no scales or keratin and are vulnerable to dessication (not the austrailian burrow frog)
- some species facilitate gas exchange via cutaneous respiration
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Integument Reptilia
- reptile skins is dry and covered by scales
- formed by a deposit of keratin within the epidermis
- turtles shell: 59 different dermal bony plates. top shell (carapace) has bony skutes which help identify species
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support and locomotion
- frog larvae: have fusiform body and a laterally compressed tail for swimming
- adult frogs: have a thinner light weight skull and jointed limbs
reptile locomotion: many forms(slithering swimming flight) so generalizations are hard
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amphibian food aquisition and digestion
- amphibian diet is broad but mainley invertebrates. larvae are aminly herbivores. adults locate prey by sight and employ sit and wait strategy.
- salamanders and caecilians rely heavily on olfaction for prey detection\
- tongue is specialized: attateched at anterior margin of jaw and folds over the floor of the mouth
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Respiration
- developed lungs that draw in air for gas exchange
- lungs specialized via vascular folding of lung lining but some do gas exchange across their sckin that may be highly folded too
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Circulation
- developed double circulation
- pulmonary circuit: blood to the lungs
- Systemic circuit: blood to the body
- have a 3-4 chambed heart for this rather than 2 hearts as it reduces energy usage
- frogs ventricle is undivided but spiral valves sends low O blood to the lungs and high O blood to the body
- when under water a muscular sphincter reduces blood flow to the lungs
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Excrition
- amphibians evolved from fresh water fish so they have an opisthonephric kidney
- this eliminates excess water thus constraining frogs from dry places (when hot they ca get water from dew drops and pools)
- some aestivate (dormant) during dry season and only come out during short wet season for mating and feeding
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Sensory abilities
- skin of amphibians sensitive to heat cold and pain
- larval amphibians have lateral line system (some adults too)
- rely on chemo reception: located in nasal epithelium, on skin, mouth, and tongue
- olfaction important for mate recognition, detection of noxious gases, and prey capture.
- they use sight for prey recognition so have large specialized eyes and large optic lobe.
- ears consist of: tympanic membrane, middle ear, and inner ear to reaceive a range of frequencies
- frog song important for mate location and attraction
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Reproduction
- amphibians
- eggs lack shells (restricts eggs to aquatic environment) and respiration occurs accross a thin outer membrane.
- anurans lay eggs in ponds and caudates lay eggs in damp sites
- tropic frogs have pouches
- reptile eggs are amniotic as they have a shell and 3 extra embryonic membranes so they can developin their own environment
- Amnion: fluid filled and surrounds embryo. provides protection from dessication and shock
- Chorion and Allantois: vascularized for efficient gas exchange
- allantois also stores waste from embryo
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