Ophiuroidea

• ophiuroidea are brittle stars
• have long arms with solid construction
• arms have no ambulcaral groove
• arms are jointed with longitudinal rows of sheilds
• arms have 2 rows of lateral sheilds, 1 aboral shield, oral shield
• oral shield frames the mouth
• one oral shield modified to form madreporite
• madreporite is on the oral surface
• have a reduced coelom
• gas exchange is limited to tube feet and 10 internal sacs
• internal sacs are the bursae
• bursae


  folds of the oral surface of the disc to form a cavity
• bauplan

  A) spines

  B) madreporite

  C) bursal slits

  D) mouth

  E) podial pores

  F) jaw

  G) oral shield

  
• bursae are connected to the outside via slits
• thin-walled respiratory bursae used for excretion
• move via a rowing motion of limbs
• spines can help provide traction
• can move limbs in any direction
• can burrow by undulating their arms
• diverse range of feeding
• suspension feeding using their podia with mucucs
• jaws and oral tube feet used to graze
• arms can loop to get larger prey
• they have no intestine or anus and their tract does not extend into the arms
• site of digestion is in the saclike stomach
• asexual reproduction through fission of the disc
• gonads can rupture into the bursae through bursal slits
• brooding of young can also occur in bursae
• larvae are called ophiopluteus
• ophiopluteus have 4 pairs of long ciliated arms
• settlement on the seabed triggers the metamorphoses
• brooding development takes longer than larvae