Meeting Abstract

P1.23  Monday, Jan. 4  New insights on larval metamorphosis in sessile rotifers: Species of Stephanoceros HOCHBERG, Adele*; HOCHBERG, Rick; University of Massachusetts Lowell; University of Massachusetts Lowell adele_hochberg@student.uml.edu

Species of Stephanoceros are sessile rotifers that reside in a gelatinous tube, have a vase-shaped body and an unusual, basket-like corona. Dispersal of sessile rotifers is effected by the production of free-swimming larvae – a derived condition in the Rotifera. The larval bodyplan is generally distinct from the adult, and to date, there are limited details on how the larva metamorphoses into the adult bodyplan. Here, we provide new details on the structure of both the larva and the adult using light microscopy and confocal laser scanning microscopy, and capture larval metamorphosis with digital video. Our observations confirm that the adult corona is produced “inside” the larval body, and that the new corona gradually extends through an opening on the larval head. The muscles that supply the coronal arms of the adult undergo a gradual metamorphic transition, whereby individual muscle blocks progressively split and form an intricate meshwork of muscle fibers within individual coronal arms. Additional details on larval development are presented.