Meeting Abstract

P1.126  Friday, Jan. 4  Development of a vitellaria larva in the brooding brittle star Ophioplocus esmarki SWEET, HC*; WOLTMAN, RA; WOOD, ME; ARMSTRONG, JM; SPIECKER, BJ; BORDER, CT; ROGGE, BJ; Rochester Institute of Technology; Rochester Institute of Technology; Rochester Institute of Technology; Rochester Institute of Technology; Rochester Institute of Technology; Rochester Institute of Technology; Rochester Institute of Technology hxssbi@rit.edu

Many echinoderms with abbreviated development quickly form the pentamerous juvenile stage and largely bypass a bilaterally symmetrical, feeding larval stage. In addition, brooding echinoderms often have highly derived forms of development. In this study, the larval form of the brooding brittle star Ophioplocus esmarki was examined. The embryos and juveniles were stained for different tissue specific markers. External features and general developmental patterns were observed. The external morphology throughout development shows typical vitellaria structures, including an anterior preoral lobe that is resorbed through time, transient transverse ciliary bands on the aboral surface, and development of juvenile structures on the mid-ventral side. A marker for a digestive enzyme is not seen in early vitellaria stages, but is present in the developing juvenile gut, suggesting that the gut is not functional until later stages of development, as in other abbreviated forms. The first skeletal elements to form are in pentamerous symmetry; there are no remnants of bilateral ophiopluteus larval spicules. Even though this is a brooding brittle star, the larvae retain the classic vitellaria shape and structure. However, they develop over a much longer period of time and they are unable to swim in the water column like non-brooded vitellaria larvae.