Excavata

Excavata is an extensive and diverse but <a href="/facts/Paraphyletic/tmTWjACz">paraphyletic</a> group of unicellular <a href="/facts/Eukaryota/SkwyPLMA">Eukaryota</a>. The group was first suggested by Simpson and Patterson in 1999 and the name latinized and assigned a rank by <a href="/facts/Thomas_Cavalier-Smith/lLMJ0j6x">Thomas Cavalier-Smith</a> in 2002. It contains a variety of free-living and symbiotic protists, and includes some important parasites of humans such as <a href="/facts/Giardia/o2FyCs8Y">Giardia</a> and <a href="/facts/Trichomonas/WsMa5GsP">Trichomonas</a>. Excavates were formerly considered to be included in the now obsolete <a href="/facts/Protists/NYVfaGVz">Protista</a> kingdom. They were distinguished from other lineages based on electron-microscopic information about how the cells are arranged (they have a distinctive <a href="/facts/Ultrastructural_identity/AmDjCudT">ultrastructural identity</a>). They are considered to be a <a href="/facts/Basal_(phylogenetics)/JQPQXpYg">basal</a> <a href="/facts/Flagellate/0XWJTXX6">flagellate</a> lineage. 
On the basis of phylogenomic analyses, the group was shown to contain three widely separated eukaryote groups, the <a href="/facts/Discobid/qnRADFMd">discobids</a>, <a href="/facts/Metamonad/IhbJKQnG">metamonads</a>, and <a href="/facts/Malawimonad/xQHkQQ98">malawimonads</a>. A current view of the composition of the excavates is given below, indicating that the group is paraphyletic. Except for some <a href="/facts/Euglenozoa/0wWA6UIF">Euglenozoa</a>, all are non-<a href="/facts/Photosynthesis/TMV7w693">photosynthetic</a>.

Excavata open-in-new

Excavata