Dear Blue Lobster:
We have a lone blue lobster in a tank with a pair of young Oscars. She has her cave and has dug it out (barricading the front) and retreated there for the last few weeks. She used to come out often to terrorize the fish and explore the tank. Now she only comes out to collect an algae wafer and only if it is right in front of her cave. Tonight we prepared to move the tank from one house to another, and in moving her we noticed she had about 25 small black eggs attached to her tail. She has been the only crustacean in the tank since we got her about 8 months ago. Immaculate conception or can they store the sperm for a REALLY long time after mating? :-) How long does it take the eggs to hatch and once they hatch, how long is it safe to leave her with then before she will start snacking on them? Thanks!!
Dear Gentle Sir:
Indeed, female crays can store sperm for years, silently producing broods based on one male's donation for several seasons. Female crays do this by use of a special compartment in their exoskeletons called the cambarum, where sperm is kept sealed off from the outside world. During mating season the female's mating instinct guides her to open the cambarum and smear the sperm across her face and vagina several times a day.
After fertilization, female crayfish will produce hundreds of eggs and carry them under her tail, at which point she is referred to as in berry. Sadly, if your female is carrying only twenty-five, the eggs were likely infertile or water conditions killed the eggs off before they could mature. In humans, this would be akin to carrying a still-born baby, giving birth to it, and dressing the tiny corpse in infant clothes and attempting to breast-feed it.
You may want to seek therapy for your female cray. Postpartum depression is a very real and very acute condition in crayfish just as it is in humans. You can take actions in your own home alongside the therapy, such as using live foods like earthworms, maggots, and dragonfly larva, exposing the cray to sunlight, and playing loud, cheerful music at all hours of the night. Your doctor may recommend psychoactive drugs for your cray, usually administered by eyedropper into the tank water.
With consistent treatment, your cray should recover from her depression and lead a long, healthy life. Good luck to you and your lady cray.