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How are diatoms different from other algae?
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Algae
The macroscopic genus of algae known as Acetabularia is commonly called “mermaid's wine glass” because of the distinctive umbrella-like shape of the tips of its stalks.
Diatoms (class Bacillariophyceae) are distinct from other algae primarily due to their unique structural and reproductive characteristics:
- Silicified Cell Walls: Unlike many other algae, diatoms possess a cell wall composed of silica, forming a pillbox-like shell known as a frustule. This shell consists of two overlapping halves, the epitheca and the hypotheca, which are often marked by intricate patterns.1
- Unique Reproduction and Size Regulation: Diatom reproduction involves a progressive decrease in cell size because each new valve formed during cell division is smaller than the original. To restore their original size, diatoms undergo a specialized process involving the formation of an auxospore, which allows the organism to grow large again.12
- Pigmentation and Storage: Diatoms store food as oil droplets. Their characteristic golden-brown color is produced by the pigment fucoxanthin, which masks the presence of chlorophyll and other carotenoid pigments.1
While many algae exhibit complex life cycles with alternating haploid and diploid stages, diatoms are predominantly diploid, and their specific method of size restoration via auxospores is a defining feature of the group.2