J. Erasmus et al., INTERNAL SHELL STRUCTURE AND GROWTH LINES IN THE SHELL OF THE ABALONE, HALIOTIS-MIDAE, Journal of shellfish research, 13(2), 1994, pp. 493-501
The internal shell structure of the South African abalone, Haliotis mi
dae, was studied using scanning electron microscopy. Growth lines were
counted. The shell consists of the periostracum, prismatic, and nacre
ous layers. The outer, noncalcified periostracum consists of a single,
honeycombed layer. Calcified layers include a simple prismatic and a
nacreous layer, the latter being composed of sheet nacre, which is unc
haracteristic of gastropods. Growth lines were deposited in the nacreo
us layer of animals, even under controlled laboratory conditions. In a
nimals of known age, three lines were deposited in the first year and
one in each subsequent year. Rate of deposition of lines was not relat
ed to diet, temperature, or photoperiod.