Family Turbinellidae Swainson, 1840. Turbinella laevigata Anton, 1839.

MATTHEWS-CASCON, H., ; DE ALMEIDA ROCHA-BARREIRA, C., ; MEIRELLES, C.A.O., ; BIGATTI G.; P.E PENCHASZADEH

Egg Masses of some Brazilian Mollusks - Desovas de alguns Moluscos Brasileiros.

Expressão Gráfica e Editora

Lugar: Fortalez; Año: 2011; p. 60 - 63

Turbinella laevigata Anton, 1839 is endemic of Brazil occurring from the state of Amapá up to the state of the Espirito Santo. It inhabits burrows in sand or mud next to beach rocks and is found from the intertidal zone up to 40 meters of depth.Turbinella laevigata has a large shell measuring up to 180 mm in length. The teleoconch has eight whorls of marked sutures and the protoconch is mamiliform, with three smooth whorls with deep sutures and the separation to the teleoconch well defined (Matthews-Cascon, 1985). The color of the shell is dull white, but is often hidden by a thick, brown periostracum. Turbinellidae species are gonochoristic and present internal fertilization.The Turbinella laevigata oothecae presents a complex and massive structure, and has in average 63 ± 6.4 SD mm of length (50.8 - 74 mm, N=15) and 41 ± 2.5 SD mm of width (38 - 45 mm, N=15). Each T. laevigata oothecae is composed in average by 15 ± 1.4 SD (13 - 18, N=15) opaque discoid capsules, with each capsule measuring in average 32.3 ± 6.4 SD mm of diameter (15.6 – 40.3 mm, N=15), and 0.4 ± 0.09 SD mm of thickness (0.22 – 0.57 mm, N=15). The capsules present in each oothecae were attached to a common basal membrane which is fused into a rigid stalk. Spawns are frequently attached to red seaweed on extremities. Each capsule has a convex and a concave surface and plaited edges, that draw out until the basal membrane, in which they join forming a median ridge.In some capsules, a disruption is found in the central area, where the capsules has fewer eggs. This disruption is probably the escape aperture. Mostly the capsules located in the two extremities of the spawning are smaller than the others, and the one near the stalk is frequently empty in thel oothecae. The egg number in each capsule are in average 240.This species has an intracapsular metamorphosis, and the juveniles found inside the capsules in more advanced stage of development presente in average, 6.4 ± 0.7 SD mm of length (5 – 8.2 mm, N = 50), and 3 complete whorls of protoconch. It is possible that it is around this size that the juveniles leave the egg capsules.Most of the egg capsules presente animals in different stages of development. In a few ootheca animals are found in more advanced stage in almost all capsules. In this spawn, newborns were counted, with 10 individuals in each capsule and a total of 150 for the whole ootheca.