Vermilion Sea Star

Mediaster aequalis

Vermilion Sea Star

Mediaster aequalis

Sandy Coast

At the Aquarium

Sandy Coast

Appearance

Vermillion sea stars have 5 rays and are around 7.9 inches in length. These sea stars are darker orange on top and light orange underneath

Habitat

Shallow rocky subtidal to ~500 meters deep (continental shelf break), can often be seen during negative tides

Larvae and juveniles are commonly found on tubes of Phyllochaetopterus prolifica (marine polychaete worms)

Adults are found on mud, sand, cobble, and rocky surfaces

Diet

Omnivore whose diet varies depending on season and substrate Algae, detritus, tunicates, sponges, and sea pens are some of this stars common food

Life History

These sea stars reach sexual maturity around 4 years of age and breed in spring, from March to May. A female will release relatively large (1 to 1.2 mm in diameter) orange eggs. The eggs float until they hatch into larvae, drifting with the currents. The larvae start settling to the seafloor at ~day 35 post-fertilization, but the larvae will only begin metamorphosis after they receive a specific chemical cue from colonies of the polychaete worm Phyllochaetopterus prolifica. They do not feed during this larval phase, surviving on stored nutrients from their egg while they seek wait for that chemical cue.

IUCN Status

Not Evaluated

Ecosystem & Cultural Importance

As animals lower on the food web, these stars are important for the transfer of nutrients from the bottom to the top of the food web. They are eaten by predators such as Dawson’s sun star.

Alaska to northern Mexico

Vermillion sea stars were impacted by the 2013-2014 outbreak of Sea Star Wasting Syndrome.

Vermillion sea stars are considered a ‘speedy’ sea star because can move up to 15.7 inches per minute! Juvenile sea stars use the mass of tubes created by a colony of Phyllochaetopterus prolifica worms as shelter

Citations & Other Resources

Bryan, Patrick J. “Energetic cost of development through metamorphosis for the seastar Mediaster aequalis (Stimpson).” Marine Biology 145 (2004): 293-302.
Biodiversity of the Central Coast website: https://www.centralcoastbiodiversity.org/vermilion-star-bull-mediaster-aequalis.html
Race Rocks Ecological Reserve website: https://racerocks.ca/mediaster-aequalis-vermillion-star-the-race-rocks-taxonomy/

Vermilion Sea Star

Vermilion Sea Star

At the Aquarium

Appearance

Habitat

Diet

Life History

IUCN Status

Ecosystem & Cultural Importance

Citations & Other Resources

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