Triploidy in the manila clam (Tapes philippinarum).
Eight semi-commercial trials are reported in which clams were induced to spawn by thermal shock, and the eggs were treated with 0.5 mg cytochalasin B/litre sea water to induce triploidy. The average triploidy rate was 74.9%. The survival rate of cytochalasin-treated and untreated larvae up to day 10 was 44.6 and 41.4% respectively, and larval shell length 211 and 204 mm. Only 34% of triploid clams spawned in response to thermal shock vs. 75% of diploids.