Tardigrada

Tardigrada (nomen a Spallanzani anno 1777 statutum) sunt animalia minima et ursiformia; e forma veniunt nomina vulgaria sicut "ursus aquaticus" (anglice "water bear," francogallice "ourson d'eau," etc.). Magnitudo tardigradorum est inter 0.15 et 1.5 mm. Pluria habent pedes octo, sed in genere hexapodibus sunt sex tantum. Systema nervi ventralis est cum gangliis in segmentis omnibus. Tardigrada supervivunt multis rebus adversis: vacuo, temperaturis sub 20 K et super 370 K, radiationibus, et ceteris. Tardigrada in aqua salina vel dulce vivunt. Vivunt in abysso maris sub 4000 m et in summis montibus super 6000 m. Tardigrada, quae in temperaturis sub 20 K se glaciant, superesse possunt ultra 50 annos.

Anatomia tardigradorum

Caput cum cerebro multilobato, ocellis, ore
Corpus divisum in quattuor segmentis
Duo pedes retractibiles pro segmento
Sine corde aut organis respiratoriis

Nexus externi

Notae

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Nielsen, C. 1995. Animal Evolution: Interrelationships of the Living Phyla. Oxford University Press, Oxford..
Ruppert, E.E., Fox, R.S. & Barnes, R.D. 2004. Invertebrate Zoology. Seventh Edition. Thomson, Brooks/Cole.: vii-xvii, 1-963, I1-I26.
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Giribet, G., Distel, D.L., Polz, M., Sterrer, W. & Wheeler, W.C. 2000. Triploblastic Relationships with Emphasis on the Acoelomates and the Position of Gnathostomulida, Cycliophora, Plathelminthes, and Chaetognatha: A Combined Approach of 18S rDNA Sequences and Morphology. Syst. Biol. 49(3): 539-562.
Kaczmarek, L. & Michalczyk, L. 2006. The Tardigrada Fauna of Mongolia (Central Asia) with a Description of Isohypsibius altai sp. nov. (Eutardigrada: Hypsibiidae). Zoological Studies 45(1). [Online]
Nelson, D.R. 2002. Current Status of the Tardigrada: Evolution and Ecology. Integ. and Comp. Biol. 42(3): 652-659.
Morgan, C.I. 1982. Tardigrada. In Parker, S.P., Synopsis and Classification of Living Organisms, vol. 2. McGraw-Hill, New York: 731-739.
Van der Land, J. 2001. Tardigrada. In Costello, M.J., Emblow, C.S. & White, R. (eds.), European Register of Marine Species. A check-list of the marine species in Europe and a bibliography of guides to their identification, Patrimoines naturels 50.