Tropical Diatoms of Costa Rica
Diatoms

What Are Diatoms?

Diatoms are a group of single-celled microscopic algae and are characterized by having cell walls made of opaline silica (i.e., biologically-derived glass). Diatoms are an important component in many food webs and are often a large proportion of the primary producer assemblage in aquatic habitats, even those habitats that are moist during part of the year (i.e., rock walls, wetlands). Diatoms often live within narrow environmental surroundings, which, depending on species, can be indicative of environmental parameters such as water temperature, water depth, nutrient concentrations, or salinity. These qualities, in addition to their rapid response to environmental change, make diatoms excellent indicators of chemical, physcial, and biological conditions in aquatic systems and surrounding terrestrial landscapes.

Diatoms are divided into centric (radially symmetric)(left) or pennate (bilaterally symmetric) diatoms (right). Much of the taxonomic identification of a diatom is based on the shape and ornamentation of its cell wall.

For more information about diatoms, visit Diatom Collection at the California Academy of Sciences.