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Plagiopyla minuta and Euplotes balteatus, Giliates of the Sea Urchin Strongylocentrotus dröbachiensis
Author(s) -
BEERS C. DALE
Publication year - 1954
Publication title -
the journal of protozoology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.067
H-Index - 77
eISSN - 1550-7408
pISSN - 0022-3921
DOI - 10.1111/j.1550-7408.1954.tb00799.x
Subject(s) - sea urchin , biology , ciliate , facultative , zoology , fishery , ecology
Of 165 sea urchins ( Strongylocentrotus dröbachiensis ) examined in the Mt. Desert Island region, 41 harbored the intestinal ciliate Plagiopyla minuta in considerable numbers. Division in this ciliate is clean; i.e. it is not accompanied by the visible elimination of macronuclear material. Long periods (probably several weeks) of vegetative life appear to alternate with brief periods of intense divisional activity in P. minuta. Twenty‐five of these same urchins also contained in their digestive tracts a species of Euplotes which was identified as E. balteatus. This hypotrich was also found commonly in the region as a free‐living organism. Dividing specimens were found regularly in the urchin, and such specimens showed the usual macronuclear reorganization which occurs in Euplotes and its near relatives. The evidence indicates that E. balteatus is a facultative commensal, which is perhaps now in the process of acquiring the endozoic habit.