| Several species of asexual endosymbionts have experienced accelerated rates of molecular evolution relative to their free-living relatives. |
| Unlike other arachnids, which are free-living, a large number of acarines have developed intimate associations with other animals. |
| Here we describe trans-splicing in the freshwater planarian Schmidtea mediterranea, a free-living member of the phylum Platyhelminthes. |
| Most species are diplohaplontic, with an alternation of free-living generations. |
| Could the fact that they are endosporous rather than free-living impose a downward selection on cell size? |
| The mostly free-living Turbellaria are found in the oceans, in fresh water, and in moist terrestrial habitats, and a few are parasitic. |
