BIOL 209 Lecture 20: Diatoms and Commercial use of Algae
Document Summary
Sexual reproduction in centric diatoms: (cid:858)ce(cid:374)trics(cid:859) are (cid:373)ost ofte(cid:374) pla(cid:374)kto(cid:374)ic. Size reduction during vegetative cell division in contrast, pennate diatoms are usually found on a solid substratum, and their gametes are amoeboid, and lack flagella the cell walls of diatoms (frustule) is amorphous opaline silica, si(oh)4 with organic coatings. Benefits/problems of silica frustules: benefits, surrounds the cell, gives it structural integrity and shelter. Inert (immune) to enzymatic attack (herbivores or microbes: silicon is plentiful in natural waters, problems, export and import, nutrient/gas exchange is more difficult, must have pores to interact with environment. Parts of a diatom frustule: hypotheca forms inside the eptheca, eptheca never triggers sexual reproduction. Some diatoms form chains, quite lethal looking, with siliceous spines: these silica spines can be harmful to fish in that they puncture their gills, spines also increase surface area, and slow sinking rate.
