After hatching, growth occurs by increase in cell size, not number. Hatching is accomplished by the piercing of the egg by the stylets and legs. Aquatic and semi-aquatic species in marine, freshwater, and damp terrestrial habitats. Typically found as part of interstitial communities, on filamentous algae, or inhabiting the surface films of mosses, lichens, and damp forest litter. Tardigrades feed on the fluids of plant and animal cells.
Some tardigrades are entirely carnivorous.
Tardigrades are prey for amoebas, nematodes, and other tardigrades. Most species appear to he eurythermal, tolerating temperatures from near freezing to upwards of 30 degrees C. Food is stored in some epidermal cells. Respiration occurs by diffusion. The animal contracts, loses water, and takes on a shriveled, wrinkled appearance. Animals have been recovered from this state after immersion in liquid helium, absolute alcohol, brine, and ether.