Bacillariophyta

Outline

Bacillariophyta -- diatoms

Introduction

Cells

only one tinsel flagellum

use fat as reserve material

siliceous cell wall = frustule

frustule = 2 valves + girdle bands

epivalve & hypovalve

Taxonomy

Pennales ("pennates")

bilateral symmetry

may have raphe

2 big chloroplasts

Centrales ("centrics")

radial symmetry

no raphe

central vacuole w/ many small discoid chloroplasts

Life cycle -- diplontic

cued by decrease in cell size

Centrics -- oogamous w/ flagellated sperm

Pennates -- isogamous

zygote forms auxospore

Ecology

marine

importance

problems

endosymbioses

freshwater

planktonic

periphytic

Fossil diatoms

diatomaceous earth: of economic importance

paleontological studies -- past climate and lake status

Vocabulary

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