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Amphibians have soft bodies with thin skins, and lack claws, defensive armour, or spines. Nevertheless, they have evolved various defence mechanisms to keep themselves alive. The first line of defence in salamanders and frogs is the mucous secretion that they produce. This keeps their skin moist and makes them slippery and difficult to grip.
Leaves have evolved multiple times - see Evolutionary history of plants. They have evolved not only in land plants, but also in various algae, like kelp. [214] Prickles, thorns and spines are all modified plant tissues that have evolved to prevent or limit herbivory, these structures have evolved independently a number of times. [215]
Temnospondyli (from Greek τέμνειν, temnein 'to cut' and σπόνδυλος, spondylos 'vertebra') or temnospondyls is a diverse ancient order of small to giant tetrapods—often considered primitive amphibians—that flourished worldwide during the Carboniferous, Permian and Triassic periods, with fossils being found on every continent.
Hatching takes place after 10 days of gestation; the young echidna, called a puggle, [23] [24] born larval and fetus-like, then sucks milk from the pores of the two milk patches (monotremes have no teats) and remains in the pouch for 45 to 55 days, [25] at which time it starts to develop spines. The mother digs a nursery burrow and deposits the ...
Made of keratin and other proteins, lamprey teeth have a hollow core to give room for replacement teeth growing under the old ones. [32] Some of the original blood-feeding forms have evolved into species that feed on both blood and flesh, and some who have become specialized to eat flesh and may even invade the internal organs of the host.
Class Amphibia (amphibians, some ancestral to the amniotes)—now a paraphyletic group; Class Synapsida (mammals and their extinct relatives) Class Sauropsida (reptiles and birds) While this traditional taxonomy is orderly, most of the groups are paraphyletic, meaning that the structure does not accurately reflect the natural evolved grouping. [47]
Amphibians are in decline worldwide, with 2 out of every 5 species threatened by extinction, according to a paper published Wednesday in the scientific journal Nature. More than 2,000 species of ...
A. clarkii may have a yellow caudal fin. Adult A. chrysopterus are darker while the head bar is broader and not constricted or discontinuous. [ 4 ] Traditionally A. akindynos was included in the clarkii complex , however genetic analysis has shown that it is significantly different from any of the other species in the clarkii complex and ...