Bigeye thresher vs

Alopias pelagicus compared with Colacium sideropus

Key Differences

• Bigeye thresher is Endangered while is Not Evaluated.

Taxonomic Classification

Rank	Bigeye thresher
Kingdom	Animalia (Animals)	Protozoa (protozoa)
Phylum	Chordata (Chordates)	Euglenozoa (Euglenozoa)
Class	Chondrichthyes (Cartilaginous Fish)	Euglenoidea (Euglenoidea)
Order	Lamniformes (Mackerel Sharks)	Euglenida (Euglenida)
Family	Alopiidae	Euglenaceae
Genus	Alopias	Colacium
Species	Alopias pelagicus	Colacium sideropus

Conservation Status

Bigeye thresher

EN — Endangered

NE — Not Evaluated

Physical Characteristics

Attribute	Bigeye thresher
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Bigeye thresher

Habitat

Typically found in marine environments from coastal waters to deep ocean.

Range

Distributed across Colombia and Taiwan. Currently classified as Endangered on the IUCN Red List, this species faces significant conservation challenges across its range.

Habitat

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

Range

Distributed across Brazil and Sweden.

Bigeye thresher

The Bigeye thresher (Alopias pelagicus) is a species in the genus Alopias. It is currently classified as Endangered on the IUCN Red List. Typically found in marine environments from coastal waters to deep ocean.

Colacium sideropus is a microscopic euglenoid protist belonging to the family Euglenaceae, characterized by its sessile, colonial lifestyle attaching to aquatic invertebrates and zooplankton. Members of the genus Colacium are distinguished from free-swimming euglenoids by their stalked or clustered growth form, anchoring to the bodies of crustaceans such as copepods and cladocerans in freshwater environments. Like other photosynthetic euglenoids, Colacium possesses chloroplasts derived from secondary endosymbiosis with a green alga, allowing it to perform photosynthesis under favorable light conditions. The relationship with host invertebrates is generally considered epibiotic rather than parasitic, with the protist colonizing the external surfaces of its host without causing significant harm. Colacium sideropus occurs in freshwater lakes, ponds, and slow-moving streams where its zooplankton hosts are abundant. Its ecological role includes contributing to microbial food webs and nutrient cycling within freshwater ecosystems. As with many microscopic protists, its true distribution and abundance are difficult to assess from macroscopic surveys, and it is likely globally distributed wherever suitable hosts exist in freshwater habitats.