Abstract:
Complete larval histories, consisting of a prezoeal stage, two
zoeal stages and one megalopal stage,are described for four species
of porcellanid anomurans. Larvae of three species were reared
from embryos through the megalopa stage in the laboratory. Larvae
of the fourth species were collected from the plankton and reared to
subsequent stages in the laboratory. The identity of these larvae
was verified on the basis of prezoeae and subsequent zoeae released
from a single female in the laboratory. Various combinations of
salinity and temperature were used in cultures to determine "ideal"
levels of these physical factors for larval rearing in the laboratory.
This revealed two points; the larvae are viable in the laboratory
only under conditions of high salinity, and temperature distinctly
influences viability and rate of larval development.
Throughout the rearing experiments observations were made
on four aspects of larval behavior, Basic respiratory movements
were found to be similar in prezoeal and zoeal stages becoming only
slightly more complex in the megalopa larva, Cleaning behavior,
unobserved in prezoeae, was simple in the zoeal stages and became
exceedlingly complex in the megalopa stage. Feeding habits and diet
ranged from nonexistence in the prezoea to carnivorous in both zoeal
stages and climaxed in the megalopa with herbivorous filter feeding.
Locomotory behavior showed a similar pattern of increasing complexity
beginning with sporadic abdominal flexion in the prezoea,
progres sing to maxilliped swimming in the zoeal stages and climaxing
in the megalopa larva with pleopodal swimming, pereiopodal
walking and later swimming by abdominal clapping.
Species studied here include Pachycheles rudis, Pachycheles
pubescens, Petrolisthes eriomerus, and Petrolisthes cinctipes.
