|
| The Indo-Pacific species (monodon, indicus and japonicus)
have 6 naupliar substages, whereas the New World species (vannamei
and stylirostris) have only 5 sub-stages. A general pattern of 3
substages for each of the zoeal and mysis stages is universally reported,
with only a few exceptions. The duration of each substage varies with the
species and rearing temperature (Treece & Yates, 1988).
|
The nauplii hatch from the eggs in a folded-over position, but quickly
straighten out. After several minutes they begin to swim, slowly at first,
but within half an hour, more brickly. Swimming is accomplished by
movement of the three pairs of appendages in paddle-like fashion, which
produces a zig-zag roll of the body. They swim briefly and then rest. The
nauplii are strongly phototropic and swim in the direction of the light
source. A rapid response by the nauplii to a light source indicates that
they are in good health. When at rest, the nauplii are suspended in a
somewhat perpendicular position with the dorsal side of the body downward
and the appendages slanted upward. During the last naupliar substage, the
body becomes somewhat flattened (