Feeding & growth
  Ophiuroids suspension-feed from the plankton, eating a variety of small invertebrates and perhaps detrital particles. No studies on growth appear to have been done on west-coast species.
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  Basket stars
  This section is divided into feeding of basket stars, considered here, and another part on BRITTLE STARS located elsewhere.
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Research study 1
 

map showing collecting sites for basket stars in San Juan Islands, WAphotograph of basket star Gorgonocephalus eucnemisBasket stars are suspension feeders, and extend their arms widely to intercept as much of the current flow as possible.  The 5 major arms branch and re-branch to form an extensive net.  The finest arm branches are covered in fine hooks used to catch small plankters.  Stomach analyses of Gorgonocephalus eucnemis in Friday Harbor Laboratories, Washington show that the main planktonic prey are crustaceans, with some chaetognaths being eaten as well.  On contact with food, the arm branches curl over and wrap themselves around the prey, with the hooks initiating and aiding in the capture.  All this wrapping forms the food into a knot, which is moved to the mouth by a rolling action of the arms.  At the mouth, the arm branches are inserted into the opening, the food is released, and special oral spines interlock to hold it in. The author notes the remnants of benthic crustacean prey in a few of the several hundred samples analysed.  Patent 1970 Ophelia 8: 145.

NOTE the ossicles in the arms of both basket and brittle stars are interconnected with collagenous connective tissue of the “catch” type.  Their special property is that they can instantly transform from a stiff, inflexible state to a soft, malleable one.  In the former state, they hold the long arms extended into the feeding current; in the latter, the arms are flexible for escape locomotion or for being folded closely to the body for protection.  The special properties and functions of “catch” connective tissues are considered elsewhere in the ODYSSEY: LEARN ABOUT SEA CUCUMBERS: WITHDRAWAL INTO CREVICES: "CATCH" CONNECTIVE TISSUES

NOTE  specimens are dredged from 40-180m depth

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CLICK HERE to see a video of a basket star Gorgonocephalus eucnemis arms partially extended in feeding posture

NOTE the video replays automatically

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Research study 2
 

Suspension-feeding in invertebrates is either active, where energy is expended to pump water through a filtering device, as in a bivalve, or to move a filtering device through water, as in a barnacle, or it is passive, where filtering depends on ambient water movement to move water past the filtering photograph of a cluster of ophiuroids feedingstructures, as in ophiuroids and crinoids.  Suspension-feeding of the active sort incurs higher metabolic costs than does the passive sort.  Most early assessments of metabolic rates of ophiuroids employ respirometer systems with the test subjects in static water conditions, thus adding extra cost of physically having to move the water past the filtering pinnules.  When a respirometer employing unidirectional laminar flows past the animals at their preferred current velocities is used, as has been done in a study on the ophiuroids Ophiopholis aculeata and Gorgonocephalus caryi at Friday Harbor Laboratories, Washington, measured metabolic rates are 0.3-0.5 those previously reported in experiments where such a current regime is not imposed.  The author notes that this is the first study on metabolic rates in a suspension-feeder under conditions that mimic natural flows in the field.  LaBarbera 1982 Comp biochem Physiol 71A: 303.

NOTE  the crinoid Florometra serratissima is also included in the study, with results similar to those obtained for the ophiuroids


Ophiuroids feeding 0.7X

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