MALE spiny lobsters ration their sperm so that their partners get enough
to fertilise their eggs鈥攁nd no more.
Mark Butler at the Old Dominion University in Norfolk, Virginia, and Alistair
MacDiarmid of the National Institute of Water and Atmospheric Research in
Wellington, New Zealand, measured the weight of spermatophores鈥攑ackets of
sperm鈥攍odged on the underbellies of female spiny lobsters (Panulirus
argus) in an aquarium. Larger females produce more eggs and the researchers
found that the males measure up their mates and control the size of their
ejaculate accordingly (Behavioral Ecology and Sociobiology, vol 46, p14).
鈥淚t鈥檚 a finely tuned process,鈥� says Butler. He speculates that the males鈥�
prudence may enable them to fertilise most of the large females without running
out of sperm.
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