Sanctuary Integrated Monitoring Network
SIMoN Tools

Species Database

Patiria miniata - Bat star

Bat star image

Geographic range:

itka, Alaska to Isla Cedros, Baja California, Mexico

Similar species:

Mediaster aequalis -- Red sea star


bay (rocky shore), bay (sandy shore), Continental shelf, exposed rocky shore, exposed sandy beaches, kelp forest, protected rocky shore, protected sandy beaches

Primary common name:

Bat star

Synonymous name(s):

Asterina miniata

General grouping:

Sea stars, urchins, cucumbers, sand dollars, brittle stars

ITIS code:


Geographic Range

Range Description:

Asterina miniata occurs from Sitka, Alaska to Isla Cedros, Baja California.

Intertidal Height

Lowest intertidal height:

0 meters OR -2 feet

Highest intertidal height:

0.90090090 meters OR 3 feet

Intertidal height notes:

Patiria miniata occurs from the low intertidal to about 293 meters.

Subtidal Depth Range

Minimum depth:

0 meters OR 0 feet

Maximum depth:

293 meters OR 975.69 feet


bay (rocky shore), bay (sandy shore), Continental shelf, exposed rocky shore, exposed sandy beaches, kelp forest, protected rocky shore, protected sandy beaches

Habitat notes:

Patiria miniata lives on rocks, among surfgrass, and on rock and sand bottoms as well as on wharf pilings.


Relative abundance:

Patiria miniata is the most abundant sea star on the West Coast. It is a common resident of protected-rock habitats, in the low intertidal and in kelp forests.

Species Description

General description:

Patiria miniata belongs to the Phylum Echinodermata and the Class Stelleroidea. All echinoderms exhibit fivefold radial symmetry in portions of their body at some stage of life.

Distinctive features:

Patiria miniata varies greatly in pattern and color from yellow to red to purple. This sea star usually has five, but sometimes four to nine broad short arms. Patiria miniata lacks spines or pedicellariae.


Patiria miniata can grow to a diameter of about 20 cm.

Natural History

General natural history:

Patiria miniata possess a hydraulic water vascular system, a network of fluid-filled canals that function in locomotion, feeding, and gas exchange. They also possess an open and reduced circulatory system, and have a complete digestive tube (tubular gut). They also have a mesodermal endoskeleton made of tiny calcified plates and spines, that forms a rigid support contained within tissues of the organism.

Time-lapse photography of Patiria miniata has shown that the animals slowly but surely tear about in a dynamic social interaction that we, living at our much faster tempto, could not otherwise imagine. Patiria miniata has a commensal polychaete, Ophiodromus pugettensis, that can be found on the oral surface.


Patiria miniata feeds on a variety of dead or alive plant and animal matter, that may include drift algae, tube worms, and solitary corals.

Feeding behavior

Omnivore, Scavenger

Feeding behavior notes:

Patiria miniata feeds by extending its stomach over its food item. Patiria miniata is known to exhibit aggressive behavior toward one another, usually when food gathering.

January - December


During spawning, female Patiria miniata emit flocculent material from pores near the bases of their arms and males appear to be “smoking” as they release sperm. Spawning is believed to be initiated by phytoplankton blooms which assure food for the larvae. Patiria miniata respond to chemicals coincident with these favorable conditions. In general, Patiria miniata has an usually long breeding period and will discharge their ripe sperm and eggs at almost any time of the year, especially during the late winter and spring.
Click on an image below to view a larger version in the SIMoN Photo Library. You will also be able to view important information on each photo such as photographer, date, caption and more.
Gotshall, D. 2005. Guide to marine invertebrates : Alaska to Baja California. Sea Challengers, Monterey, CA. 117 p.
Langstroth, L. and L. Langstroth. 2000. A Living Bay: The Underwater World of Monterey Bay. University of California Press, Berkeley and Los Angeles, CA. 287 p.
Meinkoth, N.A. 1998. National Audubon Society Field Guide to North American Seashore Creatures. A.A. Knopf, New York, NY. 813 p.
Ricketts, E. F., J. Calvin, and J.W. Hedgpeth. 1985. Between Pacific tides. Stanford University Press, Stanford, CA. 652 p.
Wobber, D.R. 1975. Agonism in asteroids. Biological Bulletin 148: 483-496.