Mediaster aequalis

Biology/Natural History: An omnivorous predator. Prey include sponges, bryozoans, sea pens,tunicates such as Aplidium californicum and Corella spp., algae, and detritus. Predators include the seastar Solaster dawsoni. Moves fairly fast for a seastar, up to 40 cm/minute. May have an internal parasitic barnacle Dendrogaster sp. In British Columbia spawns from March to May. Juveniles often congregate subtidally among tubes of the tubedwelling polychaete Phyllochaetopterus prolifica.

This 5-rayed star has conspicuous marginal plates (picture). Aboral surface is covered with circular to oval or haxagonal, flat-topped plates (ossicles), each consisting of about 25 marginal granules and a central group of slightly different granules (picture). Up to 20 cm diameter. Orange or vermilion in color. Oral surface is lighter colored than is the aboral surface.

Alaska, California, Oregon, Washington (State)

Geographical Range: Chignik Bay, Alaska to Baja California

How to Distinguish from Similar Species: Pteraster tesselatus, Dermasterias imbricata, and Asterina miniata have similar shapes but do not have the large marginal plates. The aboral surface of Asterina miniata has ossicles but they are crescent-shaped. Pteraster tesselatus and Dermasterias imbricata have a smooth aboral surface.

Known from the nearshore.

Depth range based on 303 specimens in 1 taxon.
Water temperature and chemistry ranges based on 196 samples.

Environmental ranges
  Depth range (m): 0 - 1784
  Temperature range (°C): 2.089 - 11.845
  Nitrate (umol/L): 5.774 - 44.115
  Salinity (PPS): 31.692 - 34.554
  Oxygen (ml/l): 0.493 - 6.616
  Phosphate (umol/l): 0.883 - 3.385
  Silicate (umol/l): 10.574 - 172.042

Graphical representation

Depth range (m): 0 - 1784

Temperature range (°C): 2.089 - 11.845

Nitrate (umol/L): 5.774 - 44.115

Salinity (PPS): 31.692 - 34.554

Oxygen (ml/l): 0.493 - 6.616

Phosphate (umol/l): 0.883 - 3.385

Silicate (umol/l): 10.574 - 172.042
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

Depth Range: Low intertidal to 503 meters. In our area almost exclusively subtidal (deeper than 15 m). May be seen in fairly shallow, protected waters.

Habitat: Varies. Especially on rocky areas.

The following is a representative barcode sequence, the centroid of all available sequences for this species.

There are 17 barcode sequences available from BOLD and GenBank.  Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.  See the BOLD taxonomy browser for more complete information about this specimen and other sequences.

Download FASTA File

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 23
Specimens with Barcodes: 23
Species With Barcodes: 1