Artificial incubation and hatching of embryos of the coconut crab <i>Birgus latro</i> (Decapoda: Anomura: Coenobitidae)

Abstract

Egg loss from ovigerous females has hampered larval culture experiments for life history studies of the coconut crab Birgus latro. We conducted two preliminary experiments to develop a method to artificially incubate and hatch embryos separated from the mother: 1) manipulation of incubation duration in a pseudo-terrestrial environment and 2) manipulation of incubation temperature. In experiment 1, we incubated embryos on medical gauze moistened with seawater for 7 or 17 days at 27-28°C before incubation by immersion in seawater (27-28°C), or we continuously incubated them in seawater only. In experiment 2, we similarly incubated embryos on medical gauze until 1-2 days before hatching at 21-22°C, 24.5-25.5°C, or 27-28°C before incubation in seawater (27-28°C). Successful hatching occurred, but embryos did not hatch synchronously, and hatching continued for approximately a week. Incubating embryos in seawater continuously led to the highest hatching rates of morphologically normal zoeae; however, hatching rates of normal zoeae did not exceed 50%. Increased incubation temperature reduced the incubation duration until hatching. Zoeae could metamorphose into megalopae, but survival rates were generally low. Further studies are required to improve the hatching rate of viable larvae under artificial conditions.

Effects of Temperature on the Survival and Larval Development of Deiratonotus Japonicus (Brachyura, Camptandriidae) as a Biological Indicator

“…Larvae and prey were transferred to newly prepared rearing tanks with new filtered seawater (using the same membrane filter size of 0.45 µm, 30 PSU) using a wide-bore pipette each morning. After transfer, dihydrostreptomycine sulfate (Wako, Osaka, Japan) was added to the rearing water at 50 mg/L to prevent from bacteria attaching to the larvae [20]. The larvae were observed daily.…”