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Introduction

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Selected amphibian type

Oscaecilia ochrocephala (Caeciliidae)

Caecilians (/sɪˈsɪliən/; New Latin for 'blind ones') are a group of limbless, vermiform (worm-shaped) or serpentine (snake-shaped) amphibians with small or sometimes nonexistent eyes. They mostly live hidden in soil or in streambeds, and this cryptic lifestyle renders caecilians among the least familiar amphibians. Modern caecilians live in the tropics of South and Central America, Africa, and southern Asia. Caecilians feed on small subterranean creatures such as earthworms. The body is cylindrical and often darkly coloured, and the skull is bullet-shaped and strongly built. Caecilian heads have several unique adaptations, including fused cranial and jaw bones, a two-part system of jaw muscles, and a chemosensory tentacle in front of the eye. The skin is slimy and bears ringlike markings or grooves and may contain scales.

Modern caecilians are a clade, the order Gymnophiona' /ˌdʒɪmnəˈfaɪənə/ (or Apoda /ˈæpədə/), one of the three living amphibian groups alongside Anura (frogs) and Urodela (salamanders). Gymnophiona is a crown group, encompassing all modern caecilians and all descendants of their last common ancestor. There are more than 220 living species of caecilian classified in 10 families. Gymnophionomorpha is a recently coined name for the corresponding total group which includes Gymnophiona as well as a few extinct stem-group caecilians (extinct amphibians whose closest living relatives are caecilians but are not descended from any caecilian). Some palaeontologists have used the name Gymnophiona for the total group and the old name Apoda for the crown group'. However, Apoda has other even older uses, including as the name of a genus of Butterfly making its use potentially confusing and best avoided. 'Gymnophiona' derives from the Greek words γυμνος / gymnos (Ancient Greek for 'naked') and οφις / ophis (Ancient Greek for 'snake'), as the caecilians were originally thought to be related to snakes and to lack scales.

The study of caecilian evolution is complicated by their poor fossil record and specialized anatomy. Genetic evidence and some anatomical details (such as pedicellate teeth) support the idea that frogs, salamanders, and caecilians (collectively known as lissamphibians) are each others' closest relatives. Frogs and salamanders show many similarities to dissorophoids, a group of extinct amphibians in the order Temnospondyli. Caecilians are more controversial; many studies extend dissorophoid ancestry to caecilians. Some studies have instead argued that caecilians descend from extinct lepospondyl or stereospondyl amphibians, contradicting evidence for lissamphibian monophyly (common ancestry). Rare fossils of early gymnophionans such as Eocaecilia and Funcusvermis have helped to test the various conflicting hypotheses for the relationships between caecilians and other living and extinct amphibians. (Full article...)

Selected frog article

The Seychelles frog (Sooglossus sechellensis) is a species of frog endemic to Mahé, Silhouette and Praslin islands in the Seychelles. It inhabits the floor of damp rainforest at altitudes from 150 m (490 ft) to 991 m (3,251 ft) above sea level. Higher altitude sites are considered to be more climatically stable and more suitable. The species is present in Morne Seychellois National Park, Silhouette National Park and Praslin National Park.

The reproductive biology of this species is unusual. Eggs are laid on the ground and guarded until they hatch. The tadpoles are thereafter carried on one of their parent's backs.

The IUCN assessed the species as "Endangered" in 2013. Although it is locally common, it has a small area of occupancy (about 29 km²), a severely fragmented habitat and distribution, and a declining population, particularly at lower altitudes. It is threatened by habitat degradation due to fire and invasive species (the tree Cinnamomum verum and the yellow crazy ant, Anoplolepis gracilipes). In addition, climate change projections predict a steady shrinkage in its area of habitat due to declining rainfall. (Full article...)

Selected salamander article

Fossil of the salamander Karaurus sharovi a non-urodelan caudatan from the Middle-Late Jurassic belonging to the family Karauridae

The Caudata are a group of amphibians containing the extant salamanders (the order Urodela) and all extinct species of amphibians more closely related to salamanders than to frogs. They are typically characterized by a superficially lizard-like appearance, with slender bodies, blunt snouts, short limbs projecting at right angles to the body, and the presence of a tail in both larvae and adults.

Disagreement exists between different authorities as to the definition of the terms "Caudata" and "Urodela". Some maintain that Urodela should be restricted to the crown group, with Caudata being used for the total group. Others restrict the name Caudata to the crown group and use Urodela for the total group. The former approach seems to be most widely adopted and is used in this article. (Full article...)

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Picture slideshow

Image 1Southern Brown tree frog
Image 2Eastern newt
Image 3Albanian water frog
Image 4Limnodynastes dumerilii
Image 5Common frog
Image 6Italian tree frog
Image 7Common toads during amplexus
Image 8Phantasmal poison frog
Image 9Fire-bellied toad
Image 10Fire salamander
Image 11Dendropsophus microcephalus
Image 12Litoria chloris
Image 13Golden toad
Image 14Surprise, its an amphibian. This is a genus of South American Caecilians, blind and snake-like, which hunt through leaf litter. Photo from Wildsumaco Reserve, Ecuador.
Image 15Emerald-eyed tree frog
Image 16Agile frog
Image 17Male Smooth Newt (Lissotriton vulgaris aka Triturus vulgaris) during breeding season in the Netherlands.
Image 18Ecnomiohyla rabborum
Image 19Limosa harlequin frog
Image 20Blue Mountains tree frog
Image 21American toad
Image 22Atelopus certus
Image 23Edible Frog
Image 24Frogs
Image 25Fire salamander
Image 26Balearic green toad
Image 27Spanish painted frog
Image 28Agalychnis callidryas
Image 29New England tree frog
Image 30Blue poison dart frog
Image 31Magnificent tree frog
Image 32Iberian midwife toad
Image 33Lithobates clamitans
Image 34Fire salamander
Image 35Panamanian golden frog
Image 36White-lipped tree frog
Image 37Leaf green tree frog
Image 38Poison dart frog
Image 39Duttaphrynus melanostictus
Image 40Marsh frog
Image 41Epirus water frog

Selected toad article

Woodhouse's toad (Anaxyrus woodhousii)

Anaxyrus, containing the North American toads, is a genus of true toads in the family Bufonidae. The genus is endemic to North and Central America, and contains many familiar North American toad species such as the American toad, Woodhouse's toad, and the western toad.

Most species in this genus were initially classified in Bufo, but were split due to their genetic divergence and geographic separation. Some authorities still consider Anaxyrus to be a subgenus within Bufo. However, other authorities have disputed this classification, as doing so would also require all morphologically distinct Old World toad species to also be placed in Bufo. (Full article...)

Selected caecilian article

Battersby's caecilian (Indotyphlus battersbyi) is a slender species of caecilian endemic to the Western Ghats, India. It has a flesh-coloured body, making it look very much like a large earthworm. (Full article...)