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Science Frontiers ONLINE No. 56: Mar-Apr 1988 |
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Wandering Molluscs
"How could a mollusc which lived all its adult life cemented fast to the seabed in shallow water occur thousands of kilometers apart in the Arabian Gulf and the Caribbean? Almost identical forms of the extinct bivalve Torreites sanchezi have been found in rocks from the Caribbean and the Gulf. Peter Skelton of the Open University and Paul Wright of the University of Bristol suggest that the larval stage of the bivalve must have 'island hopped.'"
The two researchers rule out convergent evolution and note that the two seas were never any closer together. They suppose that in Cretaceous times there was an equatorial current that swept the larval forms long distances. (Anonymous; "Wandering Molluscs," New Scientist, p. 33, October 15, 1987.)
Comment. The same situation prevails for other species, such as some of the amphipods and the unique life forms dependent on seafloor vents.