How many are there? about 265 genera with about 100,000 (morphological) to 10 million (genetic) species
	How old are they? probably not before the Cretaceous (centric diatoms ~120 mya; pennates ~ 70 mya)
	Where are diatoms found? 50 % of species in freshwater habitats. 50 % are marine species. Off the Hawaiian islands, our diatom flora has nearly 100 species.
	How are their cells organized? Uninucleate organization throughout all cells.
	What pigments do they possess? Chlorophyll a, Chlorophyll c and Fucoxanthin.
	How is the chloroplast constructed? Thylakoids in stacks of 3 to 6 forming grana. Chloroplast is enclosed by double unit membrane. Chloroplast enclosed by an additional two layer membrane system (Chloroplastic Endoplasmic Reticulum or CER). This additional membrane system in continuous w/ ER of cell.
	What storage product is made? Typically oils.
	Cell wall features?  Siliceous cell wall (made of SiO2) in the shape of a petri dish and called a frustule.
	Cell  complexity? Unicells exist as free living adults or chains of cells. These cells typically have motile males and sessile eggs as gametes. Check out this diversity!

Centric diatoms have a radial symmetry in cell form:

	Cyclotella top (valve) and side (girdle) view via Light Microscopy (LM)
	Thalassiosira valve view via LM
	Planktoniella valve view via Scanning Electron Microscopy (SEM)
	Biddulphia girdle view via SEM
	Chaetoceros girdle view of chain of cells via LM
	Triceratium valve view via LM

All of these genera reproduce via the  Gametic Meiosis Life History.

Life histories among Centric diatoms demonstrates very advanced life history features with nuclei disintegration in egg formation.

	Diatoma valve and girdle views showing raphe and girdle bands via LM
	Mastogloia valve view shows raphe via SEM
	Eunotia girdle view via SEM
	Asterionella chain of cells via LM
	Navicula valve view shows raphe and chloroplast volume via LM

All of these genera reproduce via the Gametic Meiosis Life History.

	How many are there? about 130 genera with about 2,000 species.
	How old are they? probably not before the late Precambrian (600 mya).
	Where are dinoflagellates found? 10 % of species in freshwater habitats. 90 % are marine species and especially in coral reefs as coral symbiont - "zooxanthellae". Off the Hawaiian islands, our tropical dinoflagellate flora has nearly 50 spp.
	How are their cells organized? Uninucleate organization throughout all cells but mesokaryotes.
	What pigments do they possess? Chlorophyll a, Chlorophyll c and Peridinin.
	How is the chloroplast constructed? Thylakoids in stacks of 3 forming grana. Chloroplast is enclosed by double unit membrane. Chloroplast enclosed by an additional one layer membrane system (Chloroplastic Endoplasmic Reticulum or CER). This additional membrane system in continuous w/ ER of cell.
	What storage product is made? starch.
	Cell wall features?  naked cells with cellulosic plates underlying the plasmalemma; 2 flagella present.
	Cell complexity? Unicells exist as free living adults or chains of cells. These cells typically have swimming gametes. Check out this diversity!

	Peridinium
	Ceratium
	Dinophysis and Ceratium
	Tropical dinoflagellates show spectacular shapes!

All of these genera reproduce via the Zygotic Meiosis Life History.

Coral bleaching in Porites is tied to the loss of  dinoflagellate symbiont from animal cells.