Bigeye thresher vs Coastal Arrowhead

Alopias pelagicus compared with Sagittaria graminea

Key Differences

• Bigeye thresher is Endangered while Coastal Arrowhead is Not Evaluated.

Taxonomic Classification

Rank	Bigeye thresher	Coastal Arrowhead
Kingdom	Animalia (Animals)	Plantae (Plants)
Phylum	Chordata (Chordates)	Magnoliophyta (Flowering Plants)
Class	Chondrichthyes (Cartilaginous Fish)	Liliopsida (Monocots)
Order	Lamniformes (Mackerel Sharks)	Alismatales (Alismatales)
Family	Alopiidae	Alismataceae
Genus	Alopias	Sagittaria
Species	Alopias pelagicus	Sagittaria graminea

Conservation Status

Bigeye thresher

EN — Endangered

Coastal Arrowhead

NE — Not Evaluated

Physical Characteristics

Attribute	Bigeye thresher	Coastal Arrowhead
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.

Coastal Arrowhead

Habitat

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

Range

Widely distributed across Asia (China, Japan), Europe (6 countries), and North America (United States).

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.

Coastal Arrowhead

Sagittaria graminea, the coastal arrowhead or grass-leaved arrowhead, is an aquatic or semi-aquatic perennial herb in the family Alismataceae native to wetland habitats across a wide geographic range including eastern North America, parts of Asia including China and Japan, and isolated populations in Europe. The species inhabits shallow water margins, muddy shores, freshwater marshes, slow-moving streams, ditches, and pond edges, where it often forms dense emergent colonies. Sagittaria graminea is distinguished from other arrowheads by its narrow, grass-like submerged and emergent leaves that lack the pronounced arrowhead shape characteristic of the genus when leaves are fully emergent, though aerial leaves may have small basal lobes. The plant produces white three-petaled flowers arranged in whorls on tall flowering stems, with male flowers above and female flowers below. It is assessed as Not Evaluated by the IUCN. The tubers of arrowheads have historically been consumed as a starchy food by Indigenous peoples across North America. The species provides important habitat structure for aquatic invertebrates and waterfowl, and waterfowl consume the seeds and tubers. The name Sagittaria derives from the Latin for arrow, reflecting the classic arrowhead leaf shape seen in other species of the genus.