Increasing atmospheric CO2 has been diffusing across the ocean surface, acidifying the whole neritic ocean, and thereby driving all marine organisms to live in lowering pH environments. Research interest pertaining to potential biological impacts of CO2-driven ocean acidification has been centered on calcification of marine organisms, and much less is known about how ocean acidification would affect other aspects of marine faunal life. In this paper, we present our recent results on the CO2 effects on early development of the oyster Crassostrea gigas and the mussel Mytilus galloprovincialis, gonadal development of the sea urchin Hemicentrotus pulcherrimus, and growth and survival of the marine shrimp Palaemon pacificus. Shell formation of oyster veliger larvae was severely affected within 24 h by exposure to 2,260 matm PCO2 (present atmospheric PCO2 380 matm), and by 48 h only 5% of larvae developed into normal D-shaped larval stage in high CO2 conditions, as compared with ca. 70% in the control conditions. Similarly, all veliger larvae of the mussels showed morphological abnormalities such as convexation of the hinge, protrusion of mantle and malformed shells under high CO2 conditions (2,000 matm). Larval height and length were 26 ± 1.9 % and 20 ± 1.1 % smaller in the high CO2 group than in the control at 144 h, respectively. Gonadal development of sea urchin was negatively affected by 1,000 matm PCO2, and the impact was further aggravated by a simultaneous elevation of seawater temperature by 2 °C. Survival, growth and molting of the shrimp were significantly affected when reared for 15 and 30 weeks in 1,000 and 1,900 ppm CO2 conditions. These results suggest that ocean acidification projected by the end of this century and during the next few centuries has devastating effects on biological productivity of coastal oceans.