A tadpole, polliwog (also pollywog, polliwig, polwig, or purwiggy), or pollywiggle (also polliwiggle, polwiggle, or porwiggle) is the wholly aquatic An aquatic animal is an animal, either vertebrate or invertebrate, which lives in water for most or all of its life. It may breathe air or extract its oxygen from that dissolved in water through specialised organs called gills, or directly through its skin. Natural environments and the animals that live in them can be categorized as aquatic or larval stage A larva is a young (juvenile) form of animal with indirect development, going through or undergoing metamorphosis (for example, insects, amphibians, or cnidarians) in the life cycle of an amphibian Amphibians , such as frogs, toads, salamanders, newts, and caecilians, are ectothermic (or cold-blooded) animals that metamorphose from a juvenile water-breathing form, either to an adult air-breathing form, or to a paedomorph that retains some juvenile characteristics. Proteidae (mudpuppies and waterdogs) are good examples of paedomorphic species, particularly of a frog Frogs are amphibians in the order Anura , formerly referred to as Salientia (Latin salere (salio), "to jump"). Most frogs are characterized by long hind legs, a short body, webbed digits (fingers or toes), protruding eyes and the absence of a tail. Frogs are widely known as exceptional jumpers, and many of the anatomical characteristics or toad A toad is any of a number of species of amphibians in the order Anura characterized by dry, leathery skin, brown coloration, and wart-like parotoid glands. A distinction between frogs and toads, though common in popular culture, is not made in taxonomy, where toads are spread across families Bufonidae, Bombinatoridae, Discoglossidae, Pelobatidae,.
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Appellation
The name "tadpole" is from Middle English Middle English is the name given by historical linguists to the diverse forms of the English language in use between the late 11th century and about 1470, when the Chancery Standard, a form of London-based English, began to become widespread, a process aided by the introduction of the printing press into England by William Caxton in the late 1470s taddepol, made up of the elements tadde, "toad A toad is any of a number of species of amphibians in the order Anura characterized by dry, leathery skin, brown coloration, and wart-like parotoid glands. A distinction between frogs and toads, though common in popular culture, is not made in taxonomy, where toads are spread across families Bufonidae, Bombinatoridae, Discoglossidae, Pelobatidae,", and pol, "head In anatomy, the head of an animal is the rostral part that usually comprises the brain, eyes, ears, nose and mouth (all of which aid in various sensory functions, such as sight, hearing, smell, and taste). Some very simple animals may not have a head, but many bilaterally symmetric forms do" (modern English "poll The poll is a name of the part of an animal's head, alternatively referencing a point immediately behind or right between the ears. This area of the anatomy is of particular significance for the horse"). Similarly, "polliwog" and "pollywiggle" are from Middle English polwigle, made up of the same pol, "head" and wiglen, "to wiggle".
General description
Metamorphosis of Bufo bufo. Tadpole stage of Haswell's Frog.Tadpoles are young amphibians that live in the water. During the tadpole stage of the amphibian life cycle, most respire In physiology, respiration is defined as the transport of oxygen from the outside air to the cells within tissues, and the transport of carbon dioxide in the opposite direction. This is in contrast to the biochemical definition of respiration, which refers to cellular respiration: the metabolic process by which an organism obtains energy by by means of autonomous external or internal gills A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water, afterward excreting carbon dioxide. The gills of some species such as hermit crabs have adapted to allow respiration on land provided they are kept moist. The microscopic structure of a gill presents a large surface area to the external. They do not usually have arms or legs until the transition to adulthood, and typically have dorsal or fin-like appendages and a tail with which they swim by lateral undulation Undulatory locomotion is the type of motion characterized by wave-like movement patterns that act to propel an animal forward. Examples of this type of gait include crawling in snakes, or swimming in the lamprey. Although this is typically the type of gait utilized by limbless animals, some creatures with limbs, such as the salamander, choose to, similar to most fishes.
As a tadpole matures, it most commonly metamorphosizes Metamorphosis is a biological process by which an animal physically develops after birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation. Some insects, amphibians, mollusks, crustaceans, Cnidarians, echinoderms and tunicates undergo metamorphosis, which is by gradually growing limbs (usually the legs first, followed by the arms) and then (most commonly in the case of frogs) outwardly absorbing its tail by apoptosis Apoptosis is the process of programmed cell death (PCD) that may occur in multicellular organisms. Biochemical events lead to characteristic cell changes (morphology) and death. These changes include blebbing, loss of cell membrane asymmetry and attachment, cell shrinkage, nuclear fragmentation, chromatin condensation, and chromosomal DNA. 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 make way for the new diet.[1] Tadpoles are consumers. Most tadpoles are herbivorous, subsisting on algae and plants. Some species are omnivorous, eating detritus In biology, detritus is non-living particulate organic material . It typically includes the bodies or fragments of dead organisms as well as fecal material. Detritus is typically colonized by communities of microorganisms which act to decompose (or remineralize) the material. In terrestrial ecosystems, it is encountered as leaf litter and other and, when available, smaller tadpoles.[2] However, other tadpoles are normally safe from cannibalistic predation because all tadpoles in a given body of water are the same age and, therefore, the same size.
An exception to the rule of distinct differences between the tadpole (juvenile) and adult (frog, toad, salamander, etc.) stages is the axolotl The axolotl , Ambystoma mexicanum, is the best known of the Mexican neotenic mole salamanders belonging to the Tiger Salamander complex. Larvae of this species fail to undergo metamorphosis, so the adults remain aquatic and gilled. The species originates from the lake underlying Mexico City and is also called ajolote (which is also the common name. Axolotls exhibit a property called neoteny Neoteny , also called juvenilization, is the retention, by adults in a species, of traits previously seen only in juveniles (a kind of pedomorphosis), and is a subject studied in the field of developmental biology. In neoteny, the physiological (or somatic) development of an animal or organism is slowed or delayed (fallaciously, seen as a dilation, meaning that they reach sexual maturity without undergoing metamorphosis.
Fossil record
Remarkably, 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.[3] They are preserved by virtue of biofilms, with more robust structures (the jaw & bones) preserved as a carbon film.[4] 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. [3] Tadpole remains with telltale external gills are also known from several of the Labyrinthodont Labyrinthodont is an obsolete term for any member of the extinct superorder (or subclass) (Labyrinthodontia) of amphibians, which constituted some of the dominant animals of Late Paleozoic and Early Mesozoic times (about 350 to 210 million years ago). The name describes the pattern of infolding of the dentine and enamel of the teeth, which are groups.
References
- ^ http://livingaquatic.com/product_info.php?products_id=85
- ^ http://www.nilesbio.com/print_catalog/index2.php
- ^ a b Mcnamara, M. E.; Orr, P. J.; Kearns, S. L.; AlcalÁ, L.; AnadÓn, P.; PeÑalver-mollÁ, E. (2009). "Exceptionally preserved tadpoles from the Miocene of Libros, Spain: ecomorphological reconstruction and the impact of ontogeny upon taphonomy". Lethaia. doi A digital object identifier is a character string used to uniquely identify an electronic document or other object. Metadata about the object is stored in association with the DOI name and this metadata may include a location, such as a URL, where the object can be found. The DOI for a document is permanent, whereas its location and other metadata:10.1111/j.1502-3931.2009.00192.x.
- ^ Maria E. McNamara; Patrick J. Orr1, Stuart L. Kearns2, Luis Alcalá3, Pere Anadón4 and Enrique Peñalver-Mollá (2006). [http://downloads.palass.org/annual_meeting/2006/Annual2006Schedule&Abstracts.pdf "Taphonomy of exceptionally preserved tadpoles from the Miocene Libros fauna, Spain: ontogeny, ecology and mass mortality"]. The Palaeontological Association 50th Annual Meeting. http://downloads.palass.org/annual_meeting/2006/Annual2006Schedule&Abstracts.pdf.
External links
- Media related to Tadpole at Wikimedia Commons Wikimedia Commons is an online repository of free-use images, sound and other media files. It is a project of the Wikimedia Foundation, from which uploaded files can be used across all Wikimedia projects in all languages, including Wikipedia, Wikibooks, Wikisource and Wikinews, or downloaded for offsite use. The repository contains over six
- The Wiktionary Wiktionary is a multilingual, web-based project to create a free content dictionary, available in over 151 languages. Unlike standard dictionaries, it is written collaboratively by volunteers, dubbed "Wiktionarians", using wiki software, allowing articles to be changed by almost anyone with access to the website definition of tadpole
- Video of Hundreds of Tadpoles
- How to Raise Tadpoles
- Raising Tadpoles to Adulthood (University of California Berkeley)
- Mysterious tadpole rain in Japan in June 2009
Categories: Amphibians Categories: Tetrapods | Herpetology | Vertebrates | Aquatic organisms | Developmental biology
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