Download DIatoms

Nate and Solon
DIATOMS
Description:
•Phylum Bacillariophyta
•Unicellular, few in colonies
•Cell wall consists of two shells that overlap where they fit together
•Silica is deposited in the shell (intricate patterns)
•Photosynthetic (chlorophylls a and c and cartenoids) yellow/brown
•Important food source for marine organisms.
•Estimated to contribute up to 45% of the total oceanic primary
production (Photosynthesis) (large numbers)
•Energy reserves stored as oils or chrysolaminarin-water-soluble
carbohydrate
Two Basic Types of Diatoms
•With radial symmetry: wheel shaped
•With Bilateral Symmetry: Boat shaped
Location
• Common in Fresh Water but abundant in cool ocean water
•Some are part of the floating plankton, others live on rocks
and sediments.
Movement
• Gliding Movement:
• Facilitated by the secretion of a slimy material from a
small groove along the shell
Reproduction
•Mostly Asexual Reproduction
• By cell division
• The two halves of its shell separate and each becomes the larger
half of a new diatom shell
• Glass shell cannot grow
• Smaller and smaller each succeeding generation
•Sexual reproduction triggered when diatom is small
fraction of original size
• Produce shell-less gametes
• Zygote, a 2n cell results from the fusion of n gametes, grows
before producing a new shell.
Miscellaneous
 At least one species toxic shellfish poisonings,
marine mammal strandings, and deaths of over 400
sea lions
 Pseudo-nitzchia australis
 When diatoms die, shells trickle down to ocean floor
 Accumulate in layers
 Sedimentary rock
 Diatomaceous earth
 Refine sugar and process vegetable oils
 Common ingredient in scouring powders and metal polishes
 No longer added to toothpaste