MOTION IN THE OCEAN

On lobsters:

The males are particularly belligerent. Even in tanks big enough for them to have their own territory, they’ll still do battle. Backing down isn’t their style. In one holding tank, a male lobster, who had already lost both claws and most of his legs in a fight, was seen dragging himself around the tank like the dismembered knight in Monty Python and the Holy Grail, challenging other lobsters to bring it on.

But not all conflicts are resolved by violent means. Bizarrely, the lobster’s urine plays a vital part. Both sexes have their bladder located in their heads, and its contents are not just a waste product. A male lobster’s physical assault is accompanied by an intense squirt of his urine. It’s deployed like a squid’s ink or even a skunk’s spray – as a tactical device in both fighting and mating.

This same scent is also used to impress females. When she is ready to mate, a lady lobster will move to a shelter close to the dominant male and start regularly parading past his territory. If he’s impressed, he squirts a jet of urine in her direction. If she is ready, she will return the gesture. Scientists now believe that the female’s urine also contains a secreted hormone that intensifies as she gets nearer to breeding time. The effect of this secretion is to tone down the male’s aggressive urges and turn his (very tiny) brains from thoughts of crushing and killing to ones of sex and procreation.

Besides squirting her urine when ready to mate, the female lobster will also shed her shell. When she has done so, the male will then mount her soft, shell-less body and impregnate her with his sperm. She will generally remain in his lair for a week or two, until her shell has grown hard. Then she’ll be on her way. The next female in line starts her seduction tactics almost as soon as the last one has left. It’s pretty much a dream scenario for the male : he gets to laze around at home while a succession of willing females comes to call.

- from Hugh Fearnley-Whittingstall and Nick Fisher's The River Cottage Fish Book, 2007