coastal arrow worm vs Humboldt's Squirrel Monkey

Parasagitta setosa compared with Saimiri cassiquiarensis

Key Differences

• coastal arrow worm is Not Evaluated while Humboldt's Squirrel Monkey is Near Threatened.

Taxonomic Classification

Rank	coastal arrow worm	Humboldt's Squirrel Monkey
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum	Chaetognatha (arrow worms)	Chordata (Chordates)
Class	Sagittoidea (Sagittoidea)	Mammalia (Mammals)
Order	Aphragmophora (Aphragmophora)	Primates (Primates)
Family	Sagittidae	Cebidae
Genus	Parasagitta	Saimiri
Species	Parasagitta setosa	Saimiri cassiquiarensis

Evolutionary Relationship

coastal arrow worm and Humboldt's Squirrel Monkey share a common ancestor at the Kingdom level: Animalia. (Animals)

Conservation Status

coastal arrow worm

NE — Not Evaluated

Humboldt's Squirrel Monkey

NT — Near Threatened

Physical Characteristics

Attribute	coastal arrow worm	Humboldt's Squirrel Monkey
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

coastal arrow worm

Habitat

Native to Europe, inhabiting ecosystems characteristic of the region.

Range

Distributed across Denmark, Norway, and Russia.

Humboldt's Squirrel Monkey

Habitat

Typically found in diverse terrestrial and aquatic ecosystems.

Range

Distributed across Colombia and Ecuador. Listed as Near Threatened, this species requires ongoing monitoring to prevent population decline.

coastal arrow worm

Parasagitta setosa, the coastal arrow worm, is a chaetognath in the family Sagittidae inhabiting the coastal and neritic waters of the northeastern Atlantic Ocean and adjacent North Sea and Baltic Sea, with confirmed records from Denmark, Norway, and Russia. Arrow worms are small, transparent, torpedo-shaped marine invertebrates typically 1–5 centimeters long, and despite their common name, are neither worms nor closely related to any familiar animal group; they form their own phylum, Chaetognatha, comprising around 120 species. Parasagitta setosa is a predatory planktonic species, using stiff bristle-like grasping spines flanking its mouth to seize copepods, small fish larvae, and other zooplankton that form the bulk of its diet. It occupies neritic plankton communities, often occurring in brackish coastal waters and estuaries where many arrow worm species cannot tolerate reduced salinity. The species serves as an important prey item for fish including herring and sprat and functions as a significant link in coastal marine food webs. Arrow worm phylogenetic position has been debated extensively; molecular evidence places them near the base of protostome animals. The species is Not Evaluated by the IUCN, as marine zooplankton populations are rarely assessed due to monitoring challenges.