They may look soft and squishy, but cuttlefish are fierce fighters, new video reveals.
Scientists have captured the first footage of a violent mating battle between European cuttlefish in the Aegean Sea off Turkey.
Relatives of octopus and squid, cuttlefish are known for rapidly changing their skin colour, a trick they use for both camouflage and communication. Male cuttlefish dazzle females with colours, switching hues in as little as half a second.
FEROCIOUS FIGHT: MALE CUTTLEFISH BATTLE OVER MATE (NEVER BEFORE SEEN)
Scientists have observed the species mating in the lab, but no one had seen the invertebrates get busy in the wild before.
In 2011, Justine Allen of Brown University and her colleagues were filming a lone female cuttlefish when, out of nowhere, a male appeared. After they mated, the male stayed by her side, guarding her.
When a similar male approached, the two males performed a series of increasingly aggressive displays, waving their arms and flashing zebra stripes on their bodies. Then it became physical, with the animals grappling, biting, and twisting each other in a corkscrew motion amid clouds of ink. The original male finally fought off the interloper.
“We knew immediately that this was rare, and we were lucky," Allen says.
Though some of the behaviours in the video corroborated what scientists have observed in the lab, Allen was surprised by the overall intensity of the conflict.
“Cuttlefish do not have an external shell, like most molluscs, so their bodies are really vulnerable,” says Allen. “They typically fight with posturing and intimidating skin displays. But in this case, it escalated to physical violence.”
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Even so, "this is some confirmation that we’re on the right track in our understanding and also an inspiration to help us develop future experiments to tease apart the details of this mating system," says Allen.
For instance, Allen wonders about how a male's size affects whether a fight escalates.
In this case, the males were about the same size, and that could be one reason the battle went so far: If one had been bigger than the other, perhaps it would not have happened, she says.
GO OUTSIDE—AND BE PATIENT
Jean Boal, a cephalopod expert who was not involved in the research, says it's significant that this fight did not occur in a laboratory. (See "Photos: Shape-Shifting Cuttlefish Can Mimic Pictures.")
“You can learn a lot in the lab, but you never know how much of it is an artefact of being in that lab environment until you can support it with field studies,” she says.
Boal and Allen agree that more people diving and exploring with video cameras is a boon for those studying animal behaviour in the wild.
“I would encourage lots of scientists and even citizen scientists to go outside with their cameras," says Allen, "and be patient.”