Heteropod and Thecosome (Mollusca: Gastropoda) Macroplankton in the Florida Straits

Previous areal records of heteropod and thecosome molluscs obtained with single- and graded-mesh plankton nets and the Isaacs-Kidd Midwater Trawl (IKMT) are compared with a collection of late juveniles and adults from the Florida Current caught by a MOCNESS-10 trawl. Sequential depth intervals from the surface to a maximum of 750 m were quantitatively sampled on transects between Palm Beach, Florida, and Settlement Point, Grand Bahama Island, Bahamas, in August 1978 and February 1979. Of the eight heteropod and 15 thecosome species or formae captured, the most numerous were, in order of abundance, the heteropods Atlanta peroni, Pterotrachea hippocampus, P. coronata and A. inclinata, and the thecosomes Cavolinia uncinata forma uncinata, Diacria trispinosa and Clio pyramidata. Data on species abundance relative to earlier reports and gear types and on vertical distribution during day and night are presented. No notable evidence of deep-water occurrence was found.