Küsten-Pfeilwurm vs Koala

Parasagitta setosa compared with Phascolarctos cinereus

Key Differences

• Küsten-Pfeilwurm is Not Evaluated while Koala is Vulnerable.

Taxonomic Classification

Rank	Küsten-Pfeilwurm	Koala
Kingdom same	Animalia (Tier)	Animalia (Tier)
Phylum	Chaetognatha (Pfeilwürmer)	Chordata (Chordatiere)
Class	Sagittoidea (Sagittoidea)	Mammalia (Säugetiere)
Order	Aphragmophora (Aphragmophora)	Diprotodontia (Marsupials)
Family	Sagittidae	Phascolarctidae (Koalas)
Genus	Parasagitta	Phascolarctos (Koalas)
Species	Parasagitta setosa	Phascolarctos cinereus

Evolutionary Relationship

Küsten-Pfeilwurm and Koala share a common ancestor at the Kingdom level: Animalia. (Tier)

Conservation Status

Küsten-Pfeilwurm

NE — Not Evaluated

Koala

VU — Vulnerable

Population: ~100.0K

Trend: Decreasing ↓

Physical Characteristics

Attribute	Küsten-Pfeilwurm	Koala
Diet	—	Herbivore
Average Lifespan	—	15 years
Average Length	—	75 cm
Average Weight	—	10.0 kg

Habitat & Geographic Range

Küsten-Pfeilwurm

Habitat

Native to Europe, inhabiting ecosystems characteristic of the region.

Range

Distributed across Denmark, Norway, and Russia.

Koala

Habitat

Typically found in grasslands, forests, and vegetated habitats.

Range

Found in Australia. Currently classified as Vulnerable on the IUCN Red List, this species faces significant conservation challenges across its range.

Küsten-Pfeilwurm

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.

Koala

Iconic marsupial of eastern and southeastern Australia, koalas weigh up to 15 kg and spend up to 22 hours daily sleeping to conserve energy from their low-calorie eucalyptus leaf diet. Highly specialized to process toxic eucalyptus compounds that would kill most other mammals, they have gut microbiomes uniquely adapted for detoxification. Listed as Endangered in 2022, with populations decimated by chlamydia disease, habitat clearing, and climate change.