|
 In
the zoeal stages, swimming is accomplished with the first and second
antennae, as in the naupliar stage, but these are now aided by the
well-developed first and second maxillipeds. The swimming stroke is slower
than that of the nauplii, the movement appears less jerky. Characteristic
of the zoeae is their continuous feeding. The culturist can judge how well
the zoeae are feeding by the contractions of the digestive tract and the
presence of long trail of feces. Active feeding and a continued prompt
response to a light source are indications of healthy zoeae. Towards the
end of the last zoeal substage, the body becomes slightly flexed (Treece & Yates, 1988).
Size ranges of zoea stages based on measurements of P. japonicus |