Abstract

The development of Strombus gigas and S. pugilis larvae was studied over a period of 21 days in laboratory culture. Experiments were conducted at 29º ± 1º C. Veliger were reared at 200 larvas/L in 30 liter containers. Larvae were fed with the microalgae Tetraselmis suecica at 1000 cells/ml. The model of S. gigas was based on chronological appearance of the fourteen morphotogical characteristics: larvae with four lobes and 2.0 whorls, four lobes and 2.5 whorls, four lobes and 3.0 whorls, six lobes and 3.0 whorls, adult heart, left tentacle stalks begin to form, four lobes and 3.5 whorls, migration of eyes up the tentacles stalks begins, pigmentation of the mantle, pigmentation of the foot, six lobes and 3.5 whorls, six lobes and 4.0 whorls, proboseis appears, radula appears. From hatching to 21 day, fourteen development characteristics are described for both species. A comparison on time of appearance and evolution of these larval characteristics was determined between S. gigas and S. pugilis. S. gigas larvae at hatching have four velar lobes and two whorl shell, while S. pugilis larvae showed two velar lobes and one and half whorl shell. For both species the adult heart first appears on the 11th day; however S. gigas larvae showed 100% of the characteristics at 16 days versus S. pugilis larvae that developed the adult heart (100%) at 21 days. The proboseis appears on day 18 in S. gigas, while for S. pugilis it appeared at 20 days. In general, based on fourteen morphological caracters S. gigas larvae exhibited more rapid development than S. pugilis larvae.

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