Monday, May 30, 2011

Coronate larva of bryozoan Schizoporella

This is a dark-field picture of a coronate larva of a bryozoan Schizoporella japonica. The bryozoan colony was collected together with a mussel off a boat dock in Charleston, OR. Seen in this picture is the apical disc (lighter-colored circle in the middle) and on both sides of it - red pigment spots. Coronate larvae are non-feeding. This larva is brooded in an ooecium which is a specialized zooid dedicated to the care of the larva. Normally, only one embryo is brooded in an ooeciam, but on a rare occasion two may be observed. Release of these larvae is triggered by light. Schizoporella colonies reproduce throughout the year, although in some colonies reproduction declines in October and November. The maturing embryos in ooecia are approximately 250 microns in diameter. Schizoporella larvae range in color from red-orange to orange. As the embryos mature, the color changes from red to orange. These larvae settle in low intertidal and sub-tidal regions. See an earlier post about these larvae by OIMB graduate student Kira Treibergs.

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