Navicula is a genus of boat-shaped diatom (single-celled photosynthetic organisms), comprising over 1,200 species,[Oxford English Dictionary, "Navicula. 3"] Navicula is a cosmopolitan genus and species are present in both freshwater and marine environments, typically attached to surfaces (i.e. Benthic zone).
Description
Navicula species are
pennate diatoms. Their valves are typically elliptical, though some species have more pinched ends than others.
Navicula cells have two
Chloroplast, one along each side of the valve along the girdle bands.
Mobility
Navicula diatoms are highly motile and move through a gliding movement
[ Navicula Diatom: Youtube video][J Microbiol Methods. 2013 Mar;92(3):349-54. doi: 10.1016/j.mimet.2013.01.006. Epub 2013 Jan 18. Semi-circular microgrooves to observe active movements of individual Navicula pavillardii cells. Umemura K1, Haneda T, Tanabe M, Suzuki A, Kumashiro Y, Itoga K, Okano T, Mayama S.] This is done through excretion of extracellular polymeric substances (EPS). One form of EPS surrounds the outside of the cell and another is excreted through a slit in the
frustule called a raphe, allowing the cell to glide along a track.
External links
File:Navicula tripunctata 2.jpg| Navicula tripunctata
type species, scale= 50 μm
File:Lyrella hennedy 1600x contrast invertion.jpg| Lyrella hennedy
File:Navicula oblonga - 160x - Seitensicht (13465052133).jpg| Navicula oblonga
File:Navicula oblonga - 160x - Schrägsicht (13464954365).jpg| Navicula oblonga
