Some Recent Observations on the Biology of Littorina Angulifera Lam. of Biscayne and Virginia Keys, Florida

Recent studies of Littorina angulifera show a bilunar periodicity in spawning through ten months of the year. Sexual maturity is reached in about two years, or, for most snails, at a height of 15 mm. The greatest percentage of spawning occurs in those snails from 15 mm to 26 mm in height, with both spawning and copulation apparently linked with the occurrence of an inch or more of rainfall. Sperm are transferred in spermatophores. Pelagic eggs, embryos, and veligers are shed in succession to the amount of 760,000 per female in one spawning period. In the laboratory all develop to the veliger stage only but may remain alive for three weeks. Rate of growth of young snails (2.9 mm) continues to accelerate until a size of 8 mm is attained. After that, the rate of growth decelerates abruptly until a size of 14 mm is reached, after which deceleration is gradual for the remainder of the life of the animal.