Superregnum: Eukaryota
Cladus: Unikonta
Cladus: Opisthokonta
Cladus: Holozoa
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Protostomia
Cladus: Ecdysozoa
Cladus: Panarthropoda
Phylum: Tardigrada
Classis: Heterotardigrada
Ordines (2): Arthrotardigrada - Echiniscoidea
References
other references
Fontoura, P., Bartels, P.J., Jørgensen, A., Kristensen, R.M. & Hansen, J.G. 2017. A dichotomous key to the genera of the Marine Heterotardigrades (Tardigrada). Zootaxa 4294(1): 1–45. DOI: 10.11646/zootaxa.4294.1.1. Reference page.
Guidetti, R. and Bertolani, R., 2005. Tardigrade taxonomy: an updated check list of the taxa and a list of characters for their identification. Zootaxa, issue 845: 1–46. Abstract
Ramazzotti, G. and Maucci, W., 1983. Il Philum Tardigrada: III edizione riveduta e aggiornata. Memorie dell'Istituto Italiano di Idrobiologia Dott. Marco de Marchi, vol. 41: 1–1012.
Links
Zicha, Ondřej et al. Heterotardigrada – Taxon details on Biological Library (BioLib).
Heterotardigrada – Taxon details on Integrated Taxonomic Information System (ITIS).
Heterotardigrada Taxon details on Fauna Europaea
Vernacular names
The class Heterotardigrada includes tardigrades (water bears) that have cephalic appendages and legs with four separate but similar digits or claws on each. 444 species have been described.[1]
Anatomy
The anatomy of the reproductive system is an important defining feature in distinguishing the different groups of tardigrades. Heterotardigrades have gonoducts that open to the outside through a preanal gonopore, rather than opening into the rectum as in the only other confirmed class of tardigrades, the Eutardigrada. The third class, Mesotardigrada, is represented by a single species known from a single specimen that is now lost, and the location from which that specimen was collected has since been destroyed by an earthquake, so its reproductive anatomy has not been studied recently.
Ecology
Some orders of heterotardigrades are marine, others are terrestrial, but as for all tardigrades, all are aquatic in the sense that they must be surrounded by at least a film of moisture in order to be active – though they can survive in a dormant state if the habitat dries out.
References
Zhang, Z.-Q. (2011). "Animal biodiversity: An introduction to higher-level classification and taxonomic richness" (PDF). Zootaxa. 3148: 7–12. doi:10.11646/zootaxa.3148.1.3.
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