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Phylum Echinodermata > Class Asteroidea
Big sea stars
How to tell them apart?
updated Oct 08

Several different kinds of big flat sea stars commonly seen on our shores look similar.
Here's more on how to tell them apart
.

Cake sea star
Anthenea aspera
Spiny sea star
Gymnanthenea laevis
Biscuit sea star
Goniodiscaster scaber
Upperside has small bumps
and tiny bivalved pedicellaria.
Upperside has bigger bumps
and less tiny bivalved pedicellaria.
Sometimes, also large plate-like spines.
Upperside has clusters of tiny bumps and no bivalved pedicellaria.
Neat blocky plates on the margins of the arms, no spines on the arms.. Arms may be short in large specimens. More scalloped blocky plates on the margins of the body and spines on the arms. Arms long in large specimens.
Neat large blocky plates on the margins of the arms. No spines on the arm. Arms long in large specimens.
Underside pale often with chevron pattern of darker bars. Underside pale often without any patterns. Underside pale often with dark patch in the centre and blue edges on the grooves under the arms.
Large bivalved pedicellaria on the underside and on each plate on the margin of the arms. Large bivalved pedicellaria on the underside and on each plate on the margin of the arms. No bivalved pedicellaria on the underside.

More comparisons



Adult Cake sea star, these tend
to have shorter arms.

Spiny sea star, with less obvious
large bumps on the upperside.

Adult Biscuit sea star.

Adult Cake sea star.
They come in various patterns.

Juvenile Cushion stars may look like
these stars. The Cushion star's distinctive
underside helps to identify it.

Young Knobbly sea stars can be as
large as adults of the other stars.
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