The brachyuran crabs inhabit as high as on mountain top to as deep as deep-sea bottom, and consist more than four thousand species. The discarding the exoskeleton for growth provides the various types of growth and reproductive activities in crabs.
The artificial production of crab seedlings extends widely with technical development. Some technical establishment made it completely possible for massive production of seeds. The following species are now ready to restocking: in the sea ranching, frog crab
Ranina ranina, hairy crab
Erimacrus isenbeckii, swimming crab
Portunus trituberculatus, in the brackish/fresh water ranching, mud crabs
Scylla spp., Japanese mitten crab
Eriocheir japonica.
The ecological feature on crabs or any other animals is quite important knowledge when we want to ensure the production. In some cases the genetic (or species) identification of the crab is necessary for stock management. The mud crabs distributed wide range from Japan, South-east Asia to South-east Africa. Until recently, most researchers have been regarded the crabs as only one species. Actuary, the crabs must be classified into three types (or species),
S. serrata, S. tranquebarica, and
S. oceanica.
The genetic conservation is now required for many animals. This enforces us the types (species) to be managed one by one.
In this report, I present the life history (drifting larvae, habitat), growth pattern (growth at molting, maturation molt, final molt), and reproductive pattern (mating pattern, sperm holding by female, egg number) of crabs. Further more I want to discuss the biology and status of the restocking on crabs.
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