Opisthobranch of the Week Data
Chromodoris geometrica is considered to be uncommon on Okinawa, although I have seen an undetermined number of uncollected or unrecorded individuals, which might in reality elevate the uncommon status to that of common.
Chromodoris geometrica is normally considered to be a relatively shallow water animal, although two of the 6 collected animals were taken from deeper portions of the reef forefront (110ft & 180ft). However, all six of the specimens were found in areas of strewn coral rubble, crawling on top of the rubble.
Chromodoris geometrica is normally recognized and not confused with other Okinawan chromodorids, with the possible exception of the recently described (Gosliner & Behrens, 1998) and only infrequently seen, C. hintuanensis. Both C. geometrica and C. hintuanensis, have the distinctive habit of waving the anterior portion of the mantle skirt up and down as they crawl, but the green-tipped gills and rhinophores of C. geometrica, contrasted with the plum-colored gills and rhinophores of C. hintuanensis immediately separate the two animals. The color pattern of C. geometrica partially resembles some of the Okinawan phyllidiids, but the populations are dissimilar enough that they're not normally apt to be confused with one another.