This seems to be a relatively rare species at Kwajalein, where we have run across only occasional specimens, usually at night but occasionally during the day. Adults at Kwajalein have all been on the seaward reef but juveniles may also be on lagoon pinnacles. They may be more abundant in other atolls. At Rongelap, several specimens were observed in 1982 on a single dive, exposed on dead coral rubble on a lagoon pinnacle. The two fully adult specimens figured are from Kwajalein. This species is very common at Pohnpei, several hundred miles west of Kwaj.
While the adults we have seen in various places (i.e., Pohnpei, Philippines, Bali, Lembeh) are pretty consistent in appearance, juveniles can be quite variable in color and have a more distinct five-pointed crown on top. For a long time juveniles were considered to be a separate species, Bothriaster primigenius. The first juvenile below is getting close to adult shape and color.
Underside of the previous specimen.
Closeup of the middorsal crown of the specimen in the previous photo.
Closeup of the middorsal crown.
Underside of the specimen in the previous two photos.
Updated 3 December 2020
Updated 8 February 2024