The first picture was taken on the day when the larva was collected – April 12, 2012. It is a dorsal view, so one can clearly see the five pairs of large scales (elytra) running along the anterior-posterior axis. The third pair of elytrae is unpigmented, whereas the rest of them have a pigmented margin (appears golden in dark field). The larva has three pairs of large ocelli (two of which are in focus). There are also three pointed antennae on the anterior-most segment (called prostomium), all tinted with the same golden pigment as the elytrae.
The second picture was taken six days later. This is a ventral view, so one can clearly see the nine pairs of parapodia (appendages) with chaete (setae), the two ventral palps with bulbous base – one on each side of the mouth, and the two anal cirri (appendages on the posterior-most segment, called the pygidium). Worms in the genus Harmothoe either brood early embryos or spawn (release eggs and sperm) directly into the plankton. I hope to continue to follow this larva through its development during the course and try to determine which species it belongs to.
Crumrine, L. 2001. Polychaeta. In: An Identification Guide to the Larval Marine Invertebrates of the Pacific Northwest. Edited by Alan Shanks. OSU Press, Corvallis.