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Tadpoles38   NatVat  

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 Tadpole article

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A tadpole (also called pollywog or porwigle in British English) is the larval stage in the life cycle of an amphibian, particularly that of a frog or toad. The name "tadpole" is from Middle English taddepol, made up of the elements tadde, "toad", and pol, "head" (modern English "poll"). Similarly, "polliwog" is from Middle English polwygle, made up of the same pol, "head" and wiglen, "to wiggle". Tadpoles are young amphibians that usually live in the water, though a few tadpoles are semi-terrestrial (Indirana beddomii and Thoropa miliaris) and terrestrial (Indirana semipalmata and Leptodactylus andreae). During the tadpole stage of the amphibian life cycle, most respire by means of autonomous external or internal gills. They do not usually have arms or legs until the transition to adulthood, and typically have a large, flattened tail with which they swim by lateral undulation, similar to most fish. As a tadpole matures, it most commonly metamorphosizes by gradually growing limbs (usually the back legs first, followed by the front legs) and then (most commonly in the case of frogs) outwardly absorbing its tail by apoptosis. Lungs develop around the time of leg development, and tadpoles late in development will often be found near the surface of the water, where they breathe air. During the final stages of external metamorphosis, the tadpole’s mouth changes from a small, enclosed mouth at the front of the head to a large mouth the same width as the head. The intestines shorten to accommodate the new diet. Most tadpoles are herbivorous, subsisting on algae and plants. Some species are omnivorous, eating detritus and, when available, smaller tadpoles.

Tadpoles vary greatly in size, both during their development and between species. For example, in a single family, Megophryidae, length of late-stage tadpoles varies between 33 millimetres (1.3 in) and 106 millimetres (4.2 in). The tadpoles of Pseudis paradoxa grow to 25 centimetres (9.8 in), the largest of any frog. Despite their soft-bodied nature and lack of mineralised hard parts, fossil tadpoles (around 10 cm in length) have been recovered from Upper Miocene strata. They are preserved by virtue of biofilms, with more robust structures (the jaw and bones) preserved as a carbon film. In Miocene fossils from Libros, Spain, the brain case is preserved in calcium carbonate, and the nerve cord in calcium phosphate. Other parts of the tadpoles’ bodies exist as organic remains and bacterial biofilms, with sedimentary detritus present in the gut. Tadpole remains with telltale external gills are also known from several of the Labyrinthodont groups. According to Sir George Scott in the origin myths of the Wa people in China and Myanmar the first Wa originated from two female ancestors Ya Htawm and Ya Htai who spent their early phase as tadpoles (rairoh) in a lake known as Nawng Hkaeo.

In the Ancient Egyptian numerals a hieroglyphic representing a tadpole was used to denote the value of 100,000.


Credit: Wikipedia



12/24/15  12:48pm

 #2317727


NatVat
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  Message To: Tadpoles38   In reference to Message Id: 2316272


 Tadpole article

Thats a LOT of information. Thanks for doing that! Now I know a lot more than I use to about frogs!



04/06/16  03:26pm


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