Laboratory Study of the Intracapsular Development and Juvenile Growth of the Banded Murex, Hexaplex trunculus

Spawning, intracapsular development, and juvenile growth of Hexaplex trunculus were investigated in the laboratory. Each female deposited nightly an average of 138.83 ± 58.70 yellowish egg capsules per spawn. Each capsule contained 358.57 ± 102.45 eggs with an average diameter of 207.23 ± 18.18 µm. Observations on the intracapsular development showed that H. trunculus is a spiralian unequal‐cleaving gastropod, with polar lobes being extruded at early segmentation. Embryos develop within the egg capsule through the provision of nurse eggs as an extraembryonic source of nutrition. Hatching occurred after 52 d of incubation. However, the hatchlings were not completely metamorphosed because velum was still present. At this moment, the average of shell length was 1.04 ± 0.13 mm ( n = 107). The average number of hatchlings per capsule was 14.73 ± 4.40 including 3.4% malformed individuals. During the first 5 mo of life, juveniles rapidly grew in shell length (growth rate = 3.56 mm/mo). However, in the remaining period (26 mo), growth rhythm decreased considerably (growth rate = 0.64 mm/mo). The weight growth rhythm was irregular with alternation between fast and slow increases observed over the rearing experiment. This kind of data could be useful for assessing the potential of this species for future molluscan aquaculture programs.