Native SpeciesNorthern sea star

Asterias rubens
FOUND by Phoebe the Phyt...
Cape Elizabeth
ID Confirmed
Quality checked by Callie O.
Peer reviewed by
Field Notes
On June 10, 2016, Mrs Richman’s marine biology class went to Kettle Cove on a warm spring day to collect data. I was collecting data to determine if the sea star population in the Gulf of Maine is decreasing. I was collecting data on the rocky coast of Kettle cove and in the tidal pools looking under rocks for sea stars. During the forty minutes I was looking for sea stars I found three sea stars. The sea stars I found were under rocks. I look under about ten rocks to find all three of the sea stars. The sea stars were found in tidal pools attached to rocks. I was collecting data to see if the population of sea stars in the Gulf of Maine was decreasing. I can not determine whether the population of sea stars on the Gulf of Maine is increasing or decreasing, but I can say that I found more sea stars than people that went to kettle cove to look for sea stars in October.
Supporting Evidence
Photo of my evidence.
The sea star I found had a line of short spines down the center of each arm. The Asterias Ruben has the spines down the middle of each arm that Socrates them from other sea stars. The spines on the aboral surface of the Asterias Forbesi are randomly arranged.
Photo of my evidence.
The species I found was a deep purple color. This is important because the Asterias Rubens is also a deep purple color, while the Asterias Forbesi is a brownish color.
Photo of my evidence.
The species I found has tube feet arranged in four rows inside of grooves on the oral side. The Ruben also has four rows of tube feet in their grooves on the oral side. The Forbesi's tube feet are arranged in lose rows.
Species Observation: Species Looked For
Did you find it?: 
I think I found it
Scientific name:
Asterias rubens
Common name:
Northern sea star
Sampling method: 
Just looking around
Photo of our sampling method.
Place Studied
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Map this species
N 43.560959 °
W -70.219438 °
Observation Site Information
A photo of our study site.
Coastal - Beach or dune
Trip Information
Kettle Cove Ledges
Trip date: 
Fri, 2016-06-10 10:40
Town or city: 
Cape Elizabeth
Type of investigation: 
Species Survey
Time of low tide: 
Fri, 2016-06-10 10:04


It's been a while since someone posted a seastar find! Nice photos, and very clear description of the defining characteristics. Were all 3 seastars the same species? Trying to see if the populations in the Gulf of Maine are changing is a tall order, but maybe thinking about Kettle Cove is more realistic. You said you found the seastars under much of the area in Kettle Cove is made up of those types of rocks? Keep up the good work!


Great find, Phoebe the Phytoplankton! How do you think you might go about trying to figure out how many sea stars there are in Kettle Cove?