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Caecilians (/ s ɪ ˈ s ɪ l i ə n /; 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.
The golden toad of Monteverde, Costa Rica, was among the first casualties of amphibian declines.Formerly abundant, it was last seen in 1989. Since the 1980s, decreases in amphibian populations, including population decline and localized mass extinctions, have been observed in locations all over the world.
Young amphibians generally undergo metamorphosis from an aquatic larval form with gills to an air-breathing adult form with lungs. Amphibians use their skin as a secondary respiratory interface and some small terrestrial salamanders and frogs lack lungs and rely entirely on their skin.
The best known representatives of taxa that exhibit some kind of the ontogenetic niche shift are fish (e.g. migration of so-called diadromous fish between saltwater and freshwater for purpose of breeding [2]), insects (e.g. metamorphosis between different life stages; such as larva, pupa and imago [2]) and amphibians (e.g. metamorphosis from ...
A dragonfly in its final moult, undergoing metamorphosis, it begins transforming from its nymph form to an adult. Metamorphosis is a biological process by which an animal physically develops including birth transformation or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation. [1]
All the developmental processes listed above occur during metamorphosis. Examples that have been especially well studied include tail loss and other changes in the tadpole of the frog Xenopus, [32] [33] and the biology of the imaginal discs, which generate the adult body parts of the fly Drosophila melanogaster. [34] [35]
Gosner stage 31 tadpole of Nidirana leishanensis. (A) Dorsal view. (B) Lateral view. (C) Ventral view. (D) Mouth structure. [1]Gosner stage is a generalized system of describing stages of embryonal and larval development in anurans (frogs and toads).
The larval period in oviparous fish is relatively short (usually only several weeks), and larvae rapidly grow and change appearance and structure (a process termed metamorphosis) to become juveniles. During this transition larvae must switch from their yolk sac to feeding on zooplankton prey, a process which depends on typically inadequate ...