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

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

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

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)

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

Oviparous Caecilian and eggs

http://www.zsl.org/zsl-london-zoo/whats-on/caecilians-secret-world-naked-snakes,355,EV.html

http://www.google.com/imgres?hl=en&rlz=1C1CHFX_enUS368US368&tbm=isch&tbnid=p9On8swpgC5NJM:&imgrefurl=http://rhamphotheca.tumblr.com/post/11718141498/an-upclose-look-at-the-face-of-the-indian&docid=U2zOuCY8MfWLHM&imgurl=http://26.media.tumblr.com/tumblr_lte8tyB1js1qc6j5yo1_500.jpg&w=461&h=301&ei=uY8cT9OOO4mMiAKs7c2fCA&zoom=1&iact=hc&vpx=189&vpy=234&dur=489&hovh=176&hovw=267&tx=165&ty=97&sig=100888889573490374019&page=1&tbnh=150&tbnw=200&start=0&ndsp=45&ved=1t:429,r:9,s:0&biw=1920&bih=995

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

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.