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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]
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 ...
In 2006, there were believed to be 4,035 species of amphibians that depended on water at some stage during their life cycle. Of these, 1,356 (33.6%) were considered to be threatened and this figure is likely to be an underestimate because it excludes 1,427 species for which there was insufficient data to assess their status. [ 173 ]
In 2006, of 4,035 species of amphibians that depend on water during some lifecycle stage, 1,356 (33.6%) were considered to be threatened. This is likely to be an underestimate because it excludes 1,427 species for which evidence was insufficient to assess their status. [201] Frog populations have declined dramatically since the 1950s.
Bacteria inhabit soil, water, acidic hot springs, radioactive waste, [125] and the deep portions of Earth's crust. Bacteria also live in symbiotic and parasitic relationships with plants and animals. Once regarded as plants constituting the class Schizomycetes, bacteria are now classified as prokaryotes.
Amphipoda (/ æ m ˈ f ɪ p ə d ə /) is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods (/ ˈ æ m f ɪ p ɒ d z /) range in size from 1 to 340 millimetres (0.039 to 13 in) and are mostly detritivores or scavengers.
Sexual reproduction is the most common life cycle in multicellular eukaryotes, such as animals, fungi and plants. [ 6 ] [ 7 ] Sexual reproduction also occurs in some unicellular eukaryotes. [ 2 ] [ 8 ] Sexual reproduction does not occur in prokaryotes , unicellular organisms without cell nuclei , such as bacteria and archaea .
Several authors have suggested that terrestrial eggs evolved from amphibian eggs laid on land to avoid predation on the eggs and competition from other labyrinthodonts. [62] [63] The amniote egg would necessarily have had to evolve from one with an anamniote structure, as those found in fish and modern amphibians. [59]