coastal arrow worm vs koala

Parasagitta setosa compared with Phascolarctos cinereus

Key Differences

• coastal arrow worm is Not Evaluated while koala is Vulnerable.

Taxonomic Classification

Rank	coastal arrow worm	koala
Kingdom same	Animalia (动物界)	Animalia (动物界)
Phylum	Chaetognatha (毛颚动物门)	Chordata (脊索动物门)
Class	Sagittoidea (箭虫纲)	Mammalia (哺乳動物)
Order	Aphragmophora (无横肌目)	Diprotodontia (雙門齒目)
Family	Sagittidae	Phascolarctidae (Koalas)
Genus	Parasagitta	Phascolarctos (Koalas)
Species	Parasagitta setosa	Phascolarctos cinereus

Evolutionary Relationship

coastal arrow worm and koala share a common ancestor at the Kingdom level: Animalia. (动物界)

Conservation Status

coastal arrow worm

NE — Not Evaluated

koala

VU — Vulnerable

Population: ~100.0K

Trend: Decreasing ↓

Physical Characteristics

Attribute	coastal arrow worm	koala
Diet	—	Herbivore
Average Lifespan	—	15 years
Average Length	—	75 cm
Average Weight	—	10.0 kg

Habitat & Geographic Range

coastal arrow worm

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.

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.

koala

澳大利亚东部和东南部的标志性有袋类动物，体重最大可达15千克，为了节省低热量桉树叶食物所提供的能量，每天最多睡眠22小时。高度特化，能够处理会致大多数其他哺乳动物死亡的有毒桉树成分，拥有专门适应解毒功能的肠道微生物群。因衣原体病、栖息地开发和气候变化导致种群锐减，2022年被列为濒危物种。