Transcript Gymnophiona
BIOL 3300 Vertebrate Zoology: Ectotherms Herpetology http://www.amphibian.com.au/ Caecilians – Chpt. 15 What is a caecilian? • Key anatomical features? • • • • • • • Which are derived characters? What is a caecilian? • Key anatomical features? • • • Epicrionops bicolor – Digimorph.org Ichthyophis bannanicus – Digimorph.org Dermophis mexicanus – Digimorph.org Figure 15.1 The unique dual jaw-closing mechanism present in all four major clades of caecilians consists of the mechanism ancestral in vertebrates, the masseter adductor mandibulae, a muscle that pulls up on the lower jaw, and a new mechanism, the masseter interhyoideus posterior, which pulls down on the processus retroarticularis (pret) an extension of the dentary bone. The result is that the lower jaw swings up. This mechanism is progressively more developed in more derived caecilian clades. Redrawn from Nussbaum, 1983. How many caecilians? • ~ species • genera • families • Phylogenetic problems?!? Figure 15.2 A cladogram depicting relationships among the families of extant caecilians. Based on Wilkinson and Nussbaum, 2006. Natural history of caecilians? • In what habitats do they live? • What about reproduction? See Life in Cold Blood clip • Diet? What is the geographic distribution of caecilians? Figure 15.3 Geographic distribution of the extant Caeciliidae. Features of Caeciliidae (Tailless Caecilians) • Primary annuli… some 2°… _____ • • Stapes present Features of Caeciliidae (Tailless Caecilians) • Largest family (>___species) • • 100mm – 1,500mm • • Can occur in disturbed/agricultural grounds… friable-pesticides! What is the geographic distribution of caecilians? Figure 15.5 Geographic distributions of the extant Ichthyophiidae and Rhinatrematidae. Features of Ichthyophiidae (Asian Tailed Caecilians) • 1°… 2°… AND 3° annuli • • Stapes present http://en.wikipedia.org/wiki/Ichthyophiidae Features of Ichthyophiidae (Asian Tailed Caecilians) • 2nd largest family (~50) • • Size up to ~500mm • • What is the geographic distribution of caecilians? Figure 15.6 Geographic distributions of the extant Typhlonectidae, Scolecomorphidae, and Uraeotyphlidae. Features of Typhlonectidae (Aquatic Caecilians) • • • • Stapes present Features of Typhlonectidae (Aquatic Caecilians) • 3rd largest family (~10) • Size up to ~750mm • • • • What is the geographic distribution of caecilians? Figure 15.5 Geographic distributions of the extant Ichthyophiidae and Rhinatrematidae. Features of Rhinatrematidae (American tailed Caecilians) • 1°… 2°… AND 3° annuli; with numerous dermal scales • ______________ with skeletal, muscular and integumentary units • Stapes present Epicrionops bicolor http://zoologia.puce.edu.ec What is the geographic distribution of caecilians? Figure 15.6 Geographic distributions of the extant Typhlonectidae, Scolecomorphidae, and Uraeotyphlidae. Features of Scolecomorphidae (Buried-Eyed Caecilians) • 1° annuli ONLY • • • • NO stapes present What is the geographic distribution of caecilians? Figure 15.6 Geographic distributions of the extant Typhlonectidae, Scolecomorphidae, and Uraeotyphlidae. Features of Uraeotyphlidae (Kerala Caecilians) • 1° & 2° annuli, but ________________ • Dermal scales present • • Stapes present Gegeneophis primus, the new species of caecilian amphibian reported from Kerala. http://www.thehindu.com Figure 15.4 Representative caecilians. Clockwise from upper left: Sao Tome caecilian Schistometopum thomense, Caeciliidae (R. A. Nussbaum); monarch tailed caecilian Ichthyophis monarchus, Ichthyophiidae (L. L. Grismer); Bannan caecilian Ichthyophis bannanicus, Rhinatrematidae (E. D. Brodie, Jr.); African buried-eyed caecilian Scolecomorphus vittatus, Scolecomorphidae (L. W. Porras). Figure 15.7 Representative caecilians. From left: Water caecilian Typhlonectes natans, Typhlonectidae; Kannan caecilian Uraeotyphlus cf. narayana, Uraeotyphlidae (D. J. Gower, The Natural History Museum, London).