Parachela

Parachela is an order of tardigrades, microscopic ecdysozoans commonly known as water bears. It is one of the major evolutionary lineages within the class Eutardigrada. The group comprises a large and diverse array of species described from a wide range of habitats, including mosses and lichens, leaf litter, soil, freshwater, and some marine environments.

Members are typically small, usually less than 1 millimeter in length, with four pairs of legs ending in claws. They possess a buccal apparatus with stylets used for piercing food sources and a flexible cuticle that molts as they grow. The order is defined in large part by molecular phylogenetic analyses, which have complemented traditional morphology and led to revisions in delimitation of families within Parachela.

Ecology and life history: Parachela tardigrades occupy microhabitats that provide moisture and food particles; most feed on algae, diatoms, bacteria, or meiofauna, and some may be predators of nematodes or micro-arthropods. Reproduction ranges from sexual to parthenogenetic modes in different taxa.

Evolution and significance: Parachela includes many of the best-studied tardigrade species and is central to research on cryptobiosis. The group exhibits the remarkable resilience tardigrades are known for, including desiccation tolerance and resistance to extreme environmental conditions.

Taxonomic notes: Classification within Parachela is subject to revision as new molecular data become available; it remains a core division of tardigrade biodiversity.