[1] These sea stars are similar one to each other and it can be difficult to determine with certainty the species only from a photograph.

To have a certain determination, in some cases, animals should be analyzed in the laboratory or using genetic testing, but often it isn’t possible.

In order to determine the species, with a reasonable margin of error, it’s necessary to observe the appearance of the animal, in particular, based on some typical features described by principal authors that have analyzed over the years a large number of specimens in the laboratory.

The main elements, to determine the various species from photo, are: the appearance of the dorsal marginal plates and spines, the size, the shape of disc and arms.

For a good identification by sea photo it is important to take a complete picture of all the subject, a picture of the detail of the marginal plates and to measure as precisely as possible the diameter of the sea star.