Paxillosida are a large order

Order (biology)

In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...

 of sea star

Sea star

Starfish or sea stars are echinoderms belonging to the class Asteroidea. The names "starfish" and "sea star" essentially refer to members of the class Asteroidea...

s.

Characteristics

Paxillosida adults lack an anus and have no suckers on their tube feet. They do not develop the brachiolaria

Brachiolaria

A brachiolaria is the second stage of larval development in many sea stars; it follows the bipinnaria. Brachiolaria have bilateral symmetry, unlike the adult sea stars, which have a pentaradial symmetry...

 stage in their early development. They possess marginal plates, and have sessile pedicellariae

Pedicellariae

A pedicellaria is a small wrench or claw-shaped structure commonly found on Echinoderms, particularly in sea stars and sea urchins...

. They mostly inhabit soft-bottomed environments of sand or mud.

Systematics

Recent analyses suggest that Paxillosida may be a sister taxon of Asterina. The order is divided into the following families

• Astropectinidae
  Astropectinidae
  Astropectinidae is a family of sea stars in the order Paxillosida.-Genera:* Astropecten Gray, 1840 * Bathybiaster * Dipsacaster Alcock, 1893 * Dytaster * Leptychaster Smith, 1876 * Persephonaster...
  
  
• Ctenodiscidae
• Goniopectinidae
• Luidiidae
• Porcellanasteridae
• Radiasteridae