Order Gymnophiona
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Transcript of Order Gymnophiona
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Order Gymnophiona• Order Apoda if including extinct forms• Extant forms lack limbs and girdles• Extant forms have:
– Annulated bodies– Specialized dual jaw adduction mechanism– Chemosensory organ (tentacle)– Columella but no external ear– Skull morphology specialized for a fossorial lifestyle– Eyes covered by integument or bone
• 9 families (Wilkinson et al. 2011), ca. 34 genera, ca. 170 species
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Changes in integument of dermatophagic caecilians
Comparison of right black and white pictures reveals greater lipid content (dyed black) in brooding females
http://www.nature.com/nature/journal/v440/n7086/fig_tab/nature04403_F2.html
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Series of gill arches consisting of basibranchial, ceratobranchial arches & epibranchial arches. These constitue the hyoglossal skeleton. Ancestrally, the hyoglossal skeleton supports the hyiod apparatus and gills.
http://www.purposegames.com/game/9cf571a0d5
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Caecilians (Lissamphibia: Gymnophiona) are unique among vertebrates in having two sets of jaw-closing muscles, one on either side of the jaw joint. This increases the leverage of the jaw-closing muscles. The combination of the two jaw-closing systems results in high bite forces over a wide range of gape angles, an important advantage for generalist feeders such as caecilians. The relative sizes and leverage mechanics of the two closing systems allow one to exert more force when the other has a poor mechanical advantage. (Kleinteich et al. 2008)
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http://www.google.com/imgres?hl=en&rlz=1C1CHFX_enUS368US368&tbm=isch&tbnid=lPt5UbOweoQlnM:&imgrefurl=http://silverfishattack.blogspot.com/2008/12/caecilians.html&docid=uwyahFhVQoc6WM&imgurl=http://4.bp.blogspot.com/_tq35GASxSOY/STbK5ssx0zI/AAAAAAAAAVY/xhZonbje1yk/s320/2583963082_6ea28bb609.jpg&w=300&h=300&ei=eZAcT7-UHaShiQL3sfmgCA&zoom=1&iact=hc&vpx=184&vpy=142&dur=2688&hovh=225&hovw=225&tx=110&ty=130&sig=100888889573490374019&page=1&tbnh=151&tbnw=153&start=0&ndsp=43&ved=1t:429,r:0,s:0&biw=1920&bih=995
Caecilian embryoFemale and juveniles
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Oviparous Caecilian and eggs
http://www.zsl.org/zsl-london-zoo/whats-on/caecilians-secret-world-naked-snakes,355,EV.html
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http://www.google.com/imgres?hl=en&rlz=1C1CHFX_enUS368US368&tbm=isch&tbnid=krzBIRihSDsCBM:&imgrefurl=http://www.digimorph.org/specimens/Dermophis_mexicanus/&docid=6lPsQKpIDuyjtM&imgurl=http://www.digimorph.org/specimens/Dermophis_mexicanus/story1thumb.jpg&w=300&h=186&ei=uY8cT9OOO4mMiAKs7c2fCA&zoom=1&iact=rc&dur=563&sig=100888889573490374019&page=3&tbnh=119&tbnw=192&start=94&ndsp=56&ved=1t:429,r:12,s:94&tx=88&ty=50&biw=1920&bih=995
Tentacle and foramen
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http://www.nhm.ac.uk/resources-rx/images/1049/atretochoana-eiselti-head-turned-left_68453_1.jpg
http://www.nhm.ac.uk/resources-rx/images/1049/atretochoana_eiselti_banner_curved_52477_1.jpg
Atretochoana eiselti: the largest lungless Caecilian (one of two known species). The integument is highly folded for effective integumentary gas exchange and the head is dorsoventrally flattened. The species is presumably aquatic.