Characterization of embryogenesis and early larval development in the Pacific triton,Charonia tritonis(Gastropoda: Caenogastropoda)

The Pacific triton, Charonia tritonis, is one of the largest carnivorous gastropods in coral reef ecosystems. This species has been in danger of extinction for many years due to unsustainable fishing. The scarcity of information about its life history greatly limits its artificial propagation and in this study, we present information on embryogenesis and early larval development. Females produced 550–600 egg capsules during each spawn, each of which contained approximately 3000 yolky eggs that measured 428.0 ± 16.10 μm in diameter. Formation and retraction of a small polar lobe were identified during egg maturation and the first two divisions, and absorption of the polar lobe into the 3D cell was observed during the eight-cell stage. The early embryo developed into a stereoblastula by spiral cleavages, and gastrulation by epiboly ended by days 5–7. The trochophore, protoconch, and eyespots appeared at 9–12, 15–18, and 20–22 days, respectively. An average of 2000 free-swimming veligers with a shell length of 664.2 ± 49.81 μm were released from each capsule after 59 ± 4.0 days incubation at 24 ± 0.5 °C. The vela were reduced by the shedding of cilia after eight weeks, although the left tentacle was still absent after 20 weeks.