ABSTRACT
Scylla serrata (Forskal) of the family Portunidae, commonly known as the red mud crab has a wide distribution throughout the Indo-Pacific region. They abound shallow estuarine and brackish waters and are commercially fished in maritime countries like Indonesia, Australia, Fiji, Philippines, Thailand, Malaysia, Vietnam, Japan, Sri Lanka and India. Much as the class Crustacea comprises animals which have long been fished for their delectable flesh, research in crustaceans has failed to entice adequate attention on gamete preservation as the pride of place in cryobiological research has always been given to mammals. Understandably, no serious attempt has been made to extend the low-temperature preservation techniques of mammalian gametes to those of invertebrates. However, recent years have witnessed a steady increase in scientific interest in low-temperature storage of gametes of cultivable invertebrates due chiefly to their need in commercial gains in animal production. Sadly, literature on gamete preservation exposes the lacuna where crustaceans are concerned, albeit the few reports on successful storage of male gametes [1-12]. It is evident from previous studies that a cryoprotectant more effective for one biological system is less effective for another, underlining the importance of testing the cryoprotective ability of different cryoprotectants for hitherto unstudied material like the male gamete of crabs. More so, questions pertaining to the toxicity of individual cryoprotective agents for gametes, freezing damage, osmotic response to various addition and dilution procedures and to the freeze-thaw cycle are yet to be answered. Problems related to successful cryopreservation are further inflated in the case of atypical sperm of Scylla serrata, which are nonmotile and delivered during mating as sperm bundles or spermatophores. The assessment of post-thaw viability of free sperm accordingly poses problems, making mandatory parallel evolution of viability assessment techniques [8,11].
