Tardigrada

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Tardigrada

[tär′dig·rə·də]
(invertebrate zoology)
A class of microscopic, bilaterally symmetrical invertebrates in the subphylum Malacopoda; the body consists of an anterior prostomium and five segments surrounded by a soft, nonchitinous cuticle, with four pairs of ventrolateral legs.

Tardigrada

 

a phylum of very small invertebrates, closely related to the Arthropoda, to which they were assigned until recently. The short body, which measures 0.1–1.0 mm in length, lacks distinct segmentation. It has four pairs of unjointed nodulelike legs, with two to nine long, setaceous tarsal digits. There are two ocelli. The mouth organs are a pair of sharp styles that serve to pierce the cell membranes of the algae and mosses that the Tardigrada feed on. The digestive tract is a straight tube extending the length of the body. Respiration is cutaneous. The organisms are dioecious. The young, which resemble adults, emerge from deposited eggs.

Representatives of the phylum, which comprises approximately 300 species, are ubiquitous, inhabiting seas, fresh waters, moss, and soil. Terrestrial species after drying are capable of surviving years in a state of anabiosis. Members of the phylum can tolerate several hours at temperatures as low as - 271°C and as highasl50°C.

References in periodicals archive ?
Of the roughly 1,150 known species of tardigrades, M.
Given how tiny the chances are of any of these apocalyptic events actually happening, we're left with the conclusion that tardigrades will survive until the Sun expands about 1 billion years from now.
Tardigrades, also known as 'water bears' or 'moss piglets,' are considered to be the toughest animal phylum on the planet.
"Tardigrades can survive pressures that are comparable to those created when asteroids strike Earth, so a small crash like this is nothing to them," he told The Guardian.
"Tardigrades are ideal to include because they are microscopic, multicellular, and one of the most durable forms of life on planet Earth," Spivack said.
When the results of the sequencing came back, the Tokyo researchers found that the tardigrade genome was composed of more like 1.2% foreign DNA, which is a far cry from a sixth of the thing's genes coming from lateral gene transfer.
Five hundred nineteen tardigrade specimens and 16 eggs were collected, representing nine genera and 18 species.
Tardigrades are a class of microorganisms found abundantly in nature in regions spanning most climatic zones and altitudes across our seven continents.
Evolution attests that its proudest accomplishment is the incredibly resilient, microscopic and strangely adorable tardigrade.
In our preceding studies (Lokko et al., 2013, 2014), 46 new zoopsammon taxa for the Estonian fauna were registered, including 25 rotifers, 17 testate amoebae, 1 cercozoan, 1 clitellate, 1 tardigrade, and 1 harpacticoid.
& WOLF, M., 2009.--New molecular data for tardigrade phylogeny, with the erection of Paramacrobiotus gen.
STRANGER THAN FICTION It looks like a Victorian illustration from Alice in Wonderland, but this image by Nicole Ottawa is in fact a tardigrade, or water bear, which is 1mm in length and was found on moss in Crater Lake, Tanzania