海洋研究開発機構(旧:海洋科学技術センター)の潜水調査船「しんかい2000」により伊豆諸島沖のスミスカルデラから未知の平巻の腹足類が採集された。本種は,貝殻の外形からはニシキウズガイ科,あるいはイソマイマイ科の一種であるかのように見える。しかし,原殻と歯舌の形態を観察した結果,Waren&Bouchet(2001)によって異旋類のミジンハグルマガイ科の新属として記載されたLurifax属の新種L.japonicusニッポンシンカイウズマキガイ(和名新称)であることが判明した。本新種は大西洋中央海嶺産の模式種L.vitreus Waren and Bouchet,2001に次いでLurifax属に確実に同定される種であり,本属の北西大平洋新記録である。
Seasonal changes in size and density of a potamidid snail, Cerithidea cingulata (Gmelin, 1790), were studied on a tidal flat neighboring the mangrove forest at the mouth of the Atago River, southern Kyushu, Japan. Juvenile snails smaller than 2mm in shell width occurred from October through May, suggesting recruitment during this period. The proportion of snails with lips retroflexed was higher at the upper site than at the lower site. The seasonal change in size structures suggests that it takes two years for juveniles to become large-sized snails with retroflexed lips.
Seasonal changes in growth and abundance of the trochid snail Cantharidus japonicus on thalli of the brown alga Sargassum ringgoldianum were studied from June 2001 to May 2002 in Odawa Bay, eastern coast of Sagami Bay, central Honshu, Japan. The density of individuals reached its maximum in June, when the plant length of S. ringgoldianum was decreasing, and fell to a minimum in February when the plant length was increasing. The seasonal changes in abundance of C. japonicus followed the changes in S. ringgoldianum with a lag of two months. Newly settled juveniles of C. japonicus appeared in May and November, and grew rapidly thereafter. The longevity of the snails was estimated to be 18-20 months.