Painted anemone

Urticina crassicornis

Order: Actiniaria

Family: Actiniidae

Genus: Urticina

The painted anemone is a striking, slow-moving marine invertebrate easily recognized by its bright red column, often covered with white or greenish spots, and its dense crown of colourful tentacles, which may be banded in shades of white, pink, purple, or green. Individuals range from 5 to 15 centimetres in diameter, though some can exceed 25 centimetres across when fully expanded.

This species is a type of sea anemone, a relative of jellyfish and corals, but it lives a solitary life attached to hard surfaces like rocks, pilings, or even kelp holdfasts. Despite its flower-like appearance, the painted anemone is a carnivorous predator, using its stinging tentacles to capture prey.

Conservation Status: IUCN

Distribution

Found from Alaska down to California, particularly along the British Columbia coast and other temperate Pacific intertidal and subtidal zones. It lives from the low intertidal zone to depths of over 30 metres.

Habitat

Prefers rocky seafloors, kelp forests, and harbour walls, often in cool, nutrient-rich waters with moderate to strong currents. It attaches itself to stable substrates where prey is likely to pass by. In deeper water, it may be found on vertical rock faces or boulders.

Diet

Carnivorous. Feeds on a variety of zooplankton, small crustaceans, molluscs, and larval fish. Its tentacles are lined with nematocysts—microscopic stinging cells that immobilize prey before being guided into the central mouth. Like other cnidarians, it digests prey inside a central gastrovascular cavity.

Reproduction

Reproduces both sexually and asexually. In sexual reproduction, males and females release sperm and eggs into the water, with fertilized embryos developing into free-swimming planula larvae. These larvae eventually settle and develop into juvenile anemones. Asexual reproduction may occur through pedal laceration, where parts of the foot break off and form new individuals.

Adaptation

Stinging tentacles immobilize prey and deter predators
Adhesive foot (pedal disc) allows it to stay anchored in current-exposed environments
Expandable body lets it inflate or contract in response to water conditions or disturbance
Mucus coating protects from desiccation and sediment build-up
Bright colouration may serve as a warning to predators

Threats to Survival

Coastal pollution and runoff can affect water quality and prey availability
Ocean warming and acidification may impact metabolic and reproductive processes
Physical disturbance from anchors, divers, or fishing gear
Microplastic ingestion is an emerging concern for benthic feeders

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