from Wiktionary, Creative Commons Attribution/Share-Alike License
- proper n. A taxonomic phylum within the kingdom Animalia — the tardigrades.
from the GNU version of the Collaborative International Dictionary of English
- n.pl. A tribe of edentates comprising the sloths. They are noted for the slowness of their movements when on the ground. See sloth, 3.
- n.pl. An order of minute aquatic arachnids; -- called also bear animalcules, sloth animalcules, and water bears.
from The Century Dictionary and Cyclopedia
- In Illiger's classification (1811), the eighth order of mammals, containing the sloths, with which, however, the sloth-bear (Prochilus) was included.
- Water-bears or bear-animalcules, an order of Arachnida synonymous with Arctisca. (See also Macrobiotidæ.) The order is sometimes raised to the rank of a class apart from Arachnida. See cut under Arctisca.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. in some classifications considered a separate phylum: microscopic arachnid-like invertebrates living in water or damp moss having 4 pairs of legs and instead of a mouth a pair of stylets or needlelike piercing organs connected with the pharynx
The name Tardigrada means "slow walker" and was given by Italian biologist Spallanzani in 1777.
This text, for example, lists Tardigrada (water bears) as a class within the subphylum of Arachnida in the phylum Arthropoda - as opposed to the current classification of Tardigrades in their own phylum.
I am leaving out tardigrades (Tardigrada) and bdelloid rotifers (Rotifera), because, although some of their species live in mosses, lichens and in the soil and can survive desiccation much better than almost all truly terrestrial animals, they require to be surrounded with relatively large volumes of water to be active.
The order is subdivided into two groups: _Tardigrada_, or sloths, and _Effodientia_ or burrowers.
Brandon Keim, WIRED Science: It’s one small step for Tardigrada, and one giant leap for the animal kingdom: The toughest creature on Earth has survived a trip into space.