Minor Invertebrate Phyla 20 Phylum Tardigrada Phylum Tardigrada Tardigrada, or water bears, are minute forms less than a millimetre in length. Most of the 400 species are terrestrial, living in the water film that surrounds moss and lichens. One of their most intriguing features is a capacity to enter a state of suspended animation called cryptobiosis.
Activity resumes when moisture is available again.
Examples of a drawing and scanning electron micrograph of Echiniscus .