Ochre Sea Star
ExploreAnimal
Ochre Sea Star
pisaster ochraceus
The Ochre Sea Star, scientifically known as Pisaster ochraceus, is an iconic and incredibly important resident of the rocky intertidal zones along the Pacific coast of North America. Often hailed as the classic 'keystone species,' its voracious appetite for mussels prevents these bivalves from monopolizing the rocky shores. By doing so, it maintains a balanced ecosystem where algae, barnacles, and a diverse array of other marine creatures can flourish. Known for their striking colors and robust, textured bodies, they are a favorite discovery for tide pool explorers. Despite facing severe population declines in recent years due to Sea Star Wasting Syndrome, they remain a resilient symbol of marine biodiversity. Their slow-moving nature masks a predatory prowess that literally shapes the very landscape of the shorelines they inhabit.
Habitat: Found in rocky intertidal zones, often clinging to wave-swept coastal rocks or resting in shallow tide pools.
Appearance
The Ochre Sea Star is a large, heavily built starfish typically sporting five thick, tapering arms, though individuals with four to seven arms are occasionally found. True to its name, it can be bright ochre or orange, but it is just as frequently a deep, vibrant purple or brown. Its upper surface is famously rough, covered in small, white, blunt spines called ossicles that often form a distinct pentagonal or net-like pattern on the central disk. Reaching up to 36 centimeters in diameter, its underside features a mouth and deep grooves lined with thousands of tiny, sucker-tipped tube feet used for both locomotion and tightly gripping prey.
KingdomAnimaliaPhylumEchinodermataClassAsteroideaOrderForcipulatidaFamilyAsteriidaeGenusPisaster
Category
AnimalRarity
Common
Danger
1/5 · Very low
Snaps
Be the first to snap!
Interesting facts
Despite being named the 'Ochre' Sea Star, the most common color variation found in the wild is actually a vibrant purple.
It only needs a microscopic gap of 0.1 millimeters in a mussel's shell to slip its stomach inside and begin digesting the occupant.
The crucial ecological concept of a 'keystone species' was actually coined in 1969 by zoologist Robert Paine based specifically on his research of the Ochre Sea Star.
They breathe directly through their skin using tiny, delicate, tube-like structures called papulae, which extract oxygen from the surrounding seawater.
Special abilities
Ability
Stomach Eversion
It can push its stomach out through its mouth to digest prey, like mussels, directly inside their own shells.
Ability
Hydraulic Tube Feet
Utilizing a complex water vascular system, it powers thousands of tube feet to slowly but relentlessly pry open tightly sealed bivalve shells.
Ability
Limb Regeneration
If an arm is lost to a predator or injury, the sea star can completely regrow the missing appendage over time, provided the central disk remains intact.
Measurements & details
- Length
- 10-36 cm
- Weight
- 0.2-1 kg
- Lifespan
- 10-20 years
- Clutch Size
- 1000000-40000000
- Incubation
- 2-4 days
Diet & Feeding
The Ochre Sea Star is a formidable predator in the intertidal zone, primarily feeding on bivalves by prying them open and digesting them externally.
Age differences: Larvae are planktivorous, feeding on microscopic phytoplankton, before transitioning to a carnivorous diet of small invertebrates after metamorphosis.
Primary Foods
- California Mussels
- Acorn Barnacles
- Limpets
- Snails
Foraging Method
- Foraging
Ecological connections
hunts
California Mussel
Mytilus californianus
Primary prey species whose population is heavily controlled by the sea star's predatory habits.
eaten by
%2C_Point_Lobos%2C_CA%2C_US_-_May_2013.jpg&width=800)
Western Gull
Larus occidentalis
An avian predator that occasionally pries sea stars off rocks to eat them when other food is scarce.
competitor
Goose Neck Barnacle
Pollicipes polymerus
Competes with the sea star's primary prey for space on rocky substrates in the intertidal zone.
Traits
No trait badges are assigned for this object yet.
Also known as
No aliases listed yet.
Collections
Collections for this object will appear here as more themes are added.
Safety
Danger
1/5 · Very low
No special safety notes yet.
Frequently Asked Questions
How to identify Ochre Sea Star?
The easiest way to identify Ochre Sea Star is to use the Snappit nature identifier app.
How long is Ochre Sea Star?
10-36 cm
How much does Ochre Sea Star weigh?
0.2-1 kg
How long does Ochre Sea Star live?
10-20 years
What does Ochre Sea Star eat?
The Ochre Sea Star is a formidable predator in the intertidal zone, primarily feeding on bivalves by prying them open and digesting them externally.
Where is Ochre Sea Star usually found?
Found in rocky intertidal zones, often clinging to wave-swept coastal rocks or resting in shallow tide pools.
How does Ochre Sea Star hunt?
Foraging
How many eggs does Ochre Sea Star lay?
1000000-40000000
Snap Map
Zoom in to split clusters and explore where this object has been snapped.
Loading map…
Recent Snaps
Recent snaps will appear here as new observations are added.
Where to spot
Park30 sightings12 species
California, US
Arboretum at the University of California, Santa Cruz
You might spot Slender Banana Slug, Western Gull, and Red-Tailed Hawk.
View guide →
Park30 sightings12 species
California, US
Arena Cove Historic District
You might spot Harbor Seal, Ochre Sea Star, and Sea Thrift.
View guide →
Park21 sightings12 species
US
Bodega Bay
You might spot Ochre Sea Star and Giant Green Anemone.
View guide →
Zoo27 sightings12 species
California, US
Cabrillo Marine Aquarium
You might spot Sunburst Anemone and Striped Shore Crab.
View guide →
Park30 sightings12 species
Washington, US
Carl S. English, Jr., Botanical Gardens
You might spot Northern Flicker, American Robin, and Great Blue Heron.
View guide →
Park30 sightings12 species
Washington, US
Chinatown-International District
You might spot Rock Pigeon, Pigeon Guillemot, and American Crow.
View guide →