vs

Cocconeis pinnata compared with Cocconeis placentula

Taxonomic Classification

Rank
Kingdom same	Chromista (Chromista)	Chromista (Chromista)
Phylum same	Ochrophyta (Ochrophyta)	Ochrophyta (Ochrophyta)
Class same	Bacillariophyceae (Bacillariophyceae)	Bacillariophyceae (Bacillariophyceae)
Order same	Achnanthales (Achnanthales)	Achnanthales (Achnanthales)
Family same	Cocconeidaceae	Cocconeidaceae
Genus same	Cocconeis	Cocconeis
Species	Cocconeis pinnata	Cocconeis placentula

Evolutionary Relationship

and share a common ancestor at the Genus level: Cocconeis.

View Genus: Cocconeis

Conservation Status

NE — Not Evaluated

Physical Characteristics

Attribute
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Habitat

Native to Europe and South America, inhabiting ecosystems characteristic of the region.

Range

Distributed across Brazil, Norway, and Sweden.

Habitat

Native to Asia and Europe and South America, inhabiting ecosystems characteristic of the region.

Range

Distributed across Brazil, Norway, Portugal, Sweden, and Taiwan.

Cocconeis pinnata is a marine and brackish-water diatom in the family Cocconeidaceae, distinguished within the genus by the pinnate (feather-like) arrangement of its striae and the specific valve morphology of its silica frustule. As an adnate epiphyte, C. pinnata attaches to a wide variety of substrates in coastal and estuarine environments, including seagrass blades, macroalgal surfaces, sandy sediments, and biogenic hard substrates such as shells and coral rubble. The species has been documented from tropical and subtropical marine habitats across the Indo-Pacific and Atlantic, with records from South American coastal waters as well as other warm marine regions. Cocconeis pinnata plays a significant ecological role in seagrass ecosystems, where epiphytic diatom communities including this species form a productive biofilm layer on leaf surfaces that serves as food for grazing invertebrates, sea urchins, and small fish. In areas of excessive nutrient loading, however, proliferation of epiphytic algae including diatoms can shade out the underlying seagrass, contributing to meadow decline. The production and dissolution of silica frustules by marine benthic diatoms contributes to the benthic silica cycle, linking biological productivity with the geochemistry of shallow coastal sediments. Species-level identification of Cocconeis taxa requires electron microscopy due to subtle morphological differences. Conservation status has not been formally assessed.

Cocconeis placentula is among the most ubiquitous and widely studied freshwater and brackish-water diatoms worldwide, serving as a model organism for periphyton ecology and a key species in biological assessment of water quality. A member of the family Cocconeidaceae, this adnate epiphyte produces a characteristic ovoid frustule with fine transapical striae, a well-developed raphe system on one valve, and an elaborate pattern of areolae visible under electron microscopy. The species complex encompasses several morphological varieties (var. placentula, var. lineata, var. euglypta, var. acuta) that differ in fine structural details of the valve ornamentation. Cocconeis placentula colonizes the surfaces of aquatic plants, algae, rocks, and sediment particles in rivers, lakes, and ponds across a vast global range spanning Europe, the Americas, Asia, Africa, and beyond, tolerating a wide range of water temperatures, pH values, and moderate nutrient enrichment. Its abundance varies dramatically with substrate type, light availability, and water chemistry, making community composition data involving this species valuable in diatom-based paleolimnological reconstructions and modern bioassessment indices. As a benthic primary producer, C. placentula contributes substantially to the productivity of the photic benthos and serves as a dietary component for invertebrate grazers. Its remarkable cosmopolitan distribution and ecological flexibility make it one of the defining species of freshwater periphyton communities globally. Conservation status is not formally assessed.