ABSTRACT
Northern subprovinces of the Caribbean Province The northern subprovinces of the Caribbean Province, the Bermudan, Bahamian, and Antillean, are characterized as being composed primarily of archipelagos of islands. Unlike the malacofaunas of the adjacent Nicaraguan and Venezuelan Subprovinces, which contain long stretches of continental coastlines, the nonvagile (nondispersing) mollusks of the northern subprovinces are highly susceptible to genetic isolation and allopatric speciation. This has led to the evolution of numerous endemic species swarms in the shallow water areas of many of the island chains, a pattern analogous to that seen in the terrestrial environments of the Galapagos Islands. All three biogeographical subdivisions have permanent eutropical conditions and are continuously bathed in warm water, with the Gulf Stream owing across the Bermudan Subprovince and with the Antillean and Caribbean Currents surrounding the Bahamian and Antillean Subprovinces. Between the Bermuda Islands, the Bahamas, the Greater Antilles Island Arc, and the Belizean Great Barrier Reef and Atolls, over 8,000 islands and carbonate cays are now known from the areas of the three subprovinces. Altogether, this immense archipelago offers a bewildering array of marine habitats and houses some of the most spectacular malacofaunas known from the western Atlantic.
