brown hydra vs Coastal Ragweed

Hydra oligactis compared with Ambrosia hispida

Key Differences

• brown hydra is Not Evaluated while Coastal Ragweed is Least Concern.

Taxonomic Classification

Rank	brown hydra	Coastal Ragweed
Kingdom	Animalia (Animals)	Plantae (Plants)
Phylum	Cnidaria (Cnidarians)	Magnoliophyta (Flowering Plants)
Class	Hydrozoa (Hydrozoa)	Magnoliopsida (Dicots)
Order	Anthoathecata (Anthoathecata)	Asterales (Daisies & Sunflowers)
Family	Hydridae	Asteraceae (Daisy Family)
Genus	Hydra	Ambrosia
Species	Hydra oligactis	Ambrosia hispida

Conservation Status

brown hydra

NE — Not Evaluated

Coastal Ragweed

LC — Least Concern

Physical Characteristics

Attribute	brown hydra	Coastal Ragweed
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

brown hydra

Habitat

Native to Europe, inhabiting ecosystems characteristic of the region.

Range

Distributed across Denmark, Norway, and Sweden.

Coastal Ragweed

Habitat

Typically found in diverse terrestrial habitats from tropical forests to temperate regions.

Range

Found in Cuba.

brown hydra

The Brown Hydra (Hydra oligactis) is a species in the genus Hydra. Native to Europe, inhabiting ecosystems characteristic of the region. Distributed across Denmark, Norway, and Sweden. As a member of the Hydra genus, this species contributes to biodiversity in its native range.

Coastal Ragweed

Coastal ragweed (Ambrosia hispida) is a perennial herb in the family Asteraceae, native to the coastal dunes, sandy beaches, and cays of Cuba, the Bahamas, and the wider Caribbean region. It grows in pioneer beach and dune vegetation, often forming spreading colonies that help stabilise loose coastal sands. Like other members of the genus Ambrosia, it bears inconspicuous greenish-white flowers arranged in racemes; male flower heads produce wind-dispersed pollen that can trigger allergic rhinitis in sensitive individuals. The deeply lobed, hispid leaves are adapted to reflect intense solar radiation and tolerate salt spray. Coastal ragweed plays an ecological role in early dune succession, binding sand and enabling other plant species to establish. The genus is widespread globally, with several Ambrosia species considered noxious weeds in agricultural settings, though Ambrosia hispida is restricted to its native Caribbean coastal range. The IUCN assesses it as Least Concern, reflecting adequate population size across its Caribbean coastal distribution. Pressure from coastal development and tourism infrastructure poses a localised threat to dune communities it inhabits.