How do clams reproduce?   (link)

http://www.monsur.org/Main20010101_archive.html
Clams reproduce sexually. In most species, each clam is either male or female. Males release sperm, and females release eggs. The sperm unite with and fertilize the eggs in the surrounding water or in the gills of the female. Fertilized eggs of most clams develop into tiny, swimming larvae called veligers. Veligers eventually become mature clams. In some species of clams, the same individual produces both sperm and eggs.

the source article for this appears to be down...
http://school.discovery.com/homeworkhelp/worldbook/atozscience/c/117300.html
google agrees:
http://www.google.com/search?q=%22clams+reproduce%22