Investigations of Inner Continental Shelf Waters off Lower Chesapeake Bay. Part III. The Phorozooid Stage of the Tunicate Doliolum nationalis

Abstract

The phorozooid is an almost unknown stage in the asexual generation of the pelagic tunicateDoliolum nationalis Borgert. Heretofore, it has merely been reported but not described. Phorozooids were found in surface meter and half-meter net samples taken in the Atlantic Ocean within 50 miles of the Virginia coast, in December 1959 and July, August and September 1960. The mean length of the December specimens was 2.64±0.46 mm, that of the July specimens 1.86±0.21 mm. Except for a smaller average size, the absence of gonadal tissue and the presence of a ventral peduncle, a phorozooid resembles the gonozooid. the hermaphroditic stage.