Autumn Snowflake vs

Acis autumnalis compared with Cocconeis placentula

Key Differences

Autumn Snowflake is Least Concern while is Not Evaluated.

Taxonomic Classification

Rank	Autumn Snowflake
Kingdom	Plantae (Plants)	Chromista (Chromista)
Phylum	Magnoliophyta (Flowering Plants)	Ochrophyta (Ochrophyta)
Class	Liliopsida (Monocots)	Bacillariophyceae (Bacillariophyceae)
Order	Asparagales (Asparagales)	Achnanthales (Achnanthales)
Family	Amaryllidaceae	Cocconeidaceae
Genus	Acis	Cocconeis
Species	Acis autumnalis	Cocconeis placentula

Conservation Status

Autumn Snowflake

LC — Least Concern

NE — Not Evaluated

Physical Characteristics

Attribute	Autumn Snowflake
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Autumn Snowflake

Habitat

Typically found in grasslands, wetlands, forests, and cultivated landscapes.

Range

Found in Norway.

Habitat

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

Range

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

Autumn Snowflake

The Autumn Snowflake (Acis autumnalis) is a species in the genus Acis. It is currently classified as Least Concern on the IUCN Red List. Typically found in grasslands, wetlands, forests, and cultivated landscapes.

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.