The Secret Sex Life Of Cuttlefish
When hundreds of giant cuttlefish come together off the coast of South Australia to mate, competitive struggles are inevitable. But as it turns out it's not only the largest or strongest males who succeed with the ladies...
When it comes to fighting, usually the largest, strongest contestant wins. But things are not quite so simple as the larger the cuttlefish, the better the opportunity for reproduction. Not only does the female call the shots, often rejecting as much as 70 per cent of the overtures, but, in fact, the smaller, fast maturing size class cuttlefish take advantage of two large males engaging in display rivalries and fighting and pretending to be females they sneak in to copulate with the female while the big males are occupied with each other.
These 'sneaker males' are essentially actively engaging in a cuttlefish cross-dressing role: taking on the mottled patterning of females; hiding their conspicuously male fourth arm (hectocotylus) and imitating the posture of those females recently copulated and in an egg-laying mode.
By appearing to be female, these sneaker males can often approach a female right underneath the gaze of a guarding male or will simply hang around in close proximity, waiting for two large males to fight, or chase each other some distance from the receptive female. The sneaker then pops in for a bit of cuttlefish love while the big boys are duking it out. The sneaker males are successful almost 40 per cent of the time.
In this gaudy spectacle of a reproductive orgy, head-to-head mating between male and female cuttlefish last on average 2.4 minutes per copulation. This is followed by an intermission of six or seven minutes while the female deposits her eggs into an overhang or crevice. This can happen up to more than a dozen times and on on average with two to eight different males per day. It is estimated that reproductive females make up only 25 per cent of the spawning aggregation. Once the female lays her eggs, she never attends to the eggs again and keeps mating until she has exhausted her supplies of eggs and will head away from the aggregation and soon die.
The males, once they have mated with all the energy they can muster and the last receptive female has left, will then wander off to a certain, and well-earned, from the standpoint of fulfilling their only biological imperative, death.
The eggs develop on their own, if placed well, safe from predators, and they will gestate and develop for two to five months, ready, upon hatching, to hunt their prey and to mimic their surroundings to hide in plain sight, a magnificent new generation indistinguishable from their progenitors, as it has been for millions of generations.
Download our FREE March 2015 issue of DIVE magazine to read Douglas' full feature on the secret life of cuttlefish