Meeting Abstract
The green morph of the marine isopod Pentidotea resecata lives and feeds on eelgrass, while the brown morph lives on kelp. The coloration of the green morph closely matches that of its substrate. The goal of this project was to determine whether the green isopod’s coloration is due to the presence of chloroplasts and/or chlorophyll. Using spectrophotometry, we analyzed isopod tissue extracts for the presence of chlorophyll a. The extracts did exhibit peaks near 430 and 664 nm, as expected for chlorophyll a. However, acidification of the extracts produced little change in the extracts’ absorption spectra, indicating that they contained mostly pheophytin a, a degradation product of chlorophyll a. The digestive system of P. resecata consists of a mouth, esophagus, stomach, hepatopancreas, hindgut, and anus, which exits ventrally into the valve formed by the uropods. The stomach contains separate openings into both the hepatopancreas and the hindgut, which are the locations where most of the materials being digested were found on dissection. The hepatopancreas of this species consists of several tan-colored midgut glands that surround the stomach and hindgut. The hindgut contents include chunks of whole eelgrass cells and a variety of diatoms along with other debris. Although fluorescence suggests that some chlorophyll in the material within the hindgut lumen may still retain functionality, we did not find any indication of plant cells or chloroplasts within the isopod tissue itself. While it is likely that P. resecata derives its green pigmentation from its eelgrass diet, these animals do not appear to contain functional chlorophyll a within their tissues.
