Class Starfish, Asteroidea "Giant Pink Star (Pisaster brevispinus)" by Jkirkhart35 via Flickr, Creative Commons Attribution.

Class Brittle star, Ophiuroidea "Sanc0448" by NOAA Photo Library via Flickr, Creative Commons Attribution.

Taxonomy:

Class Starfish, Asteroidea

Ord. Brisingida (Add)
Ord. Forcipulatida (Add)
Ord. Notomyotida (Add)
Ord. Paxillosida (Add)
Ord. Peripoda (Add)
Ord. Platyasterida (Add)
Ord. Spinulosida (Add)
Ord. Valvatida (Add)

Class Brittle star, Ophiuroidea

Ord. Oegophiurida (Add)
Ord. Ophiurida (Add)
Ord. Phrynophiurida (Add)
Ord. Stenurida (Add)