Male octopuses have a big problem: female octopuses. Each male wants to mate and pass on his genes to a new generation. The trouble is, the female is often larger and hungrier than he is, so there is a constant risk that, instead of mating, the female will strangle him and eat him.
The males have a host of tricks to survive the mating process. Some of them can quite literally mate at arm’s length. Others sneak into a female’s den disguised as another gal, or sacrifice their entire mating arm to the female and then make a hasty retreat.
It’s all very macabre. It’s also a paradox. Octopuses are some of the most antisocial, unfriendly animals alive. Yet their bodies have evolved in such a way that they must mate in the most intimate way possible: the male has to insert his sperm directly into the female’s body using one of his arms. The resulting mating practices are not just a curiosity: they are a window onto how octopuses have evolved into the creatures they are today.
Octopuses and their close cousins the squid all belong to a group of animals called cephalopods. Both are actually molluscs, making them close relatives of oysters and limpets, but they have lost their shells.
Octopuses tend to be profoundly antagonistic towards each other. Unlike gregarious animals like dolphins, they appear to see their own kind primarily as competition, and sometimes food.
There’s always the threat of cannibalism
Squid, which are downright social by comparison, mate in a distinctly unromantic way. A male squid swims by and deposits sperm in one quick move outside of the female’s body. She can decide later whether to accept it.
But not so the octopus. “Octopus mating is definitely different than other cephalopods,” says marine biologist Jean Boal of Millersville University in Pennsylvania. The male must deposit his sperm inside the female’s body, at the risk of his life.
In our second Reef Threads Plus podcast we welcome Richard Ross and Kathy Leahy to address the difficult question: Is the hobby cruel to animals? We hope you enjoy the discussion and that it gets you to think and share with your fellow hobbyists. As always, you can download the podcast here, or subscribe to our podcasts at iTunes. Also, follow us on Twitter @reefthreads. We hope you enjoy our new series, find it thought provoking, and will share it with others.—Gary and Christine
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Alternate copy of video: https://vimeo.com/124145465
Over the summer, biologists from the California Academy of Sciences in San Francisco returned from an expedition to the Philippines with some very rare and diminutive guests, a mating pair of pygmy seahorses. The two tiny fish, each shorter than an inch and bright orange, were collected as part of a larger study of the stunning biodiversity found in the “Twilight Zone” of the ocean. It’s a relatively unexplored environment located at depths where the bright tropical sunlight barely penetrates.
Pygmy seahorses live their entire adult lives attached to a type of coral called a Gorgonian sea fan. The seahorses use their long tails to grab on to the delicately branched sea fans. But what’s really amazing is their ability to match the coral’s bright color and knobby texture. They blend in so perfectly that they are barely visible, even to a trained eye.
More people have walked on the moon than have seen a juvenile land on a sea fan.
Pygmy seahorses are nearly impossible to raise in captivity. More people have walked on the moon than have seen a juvenile land on a sea fan. Until recently, there was no record of the seahorses ever living long enough to breed in an aquarium. As a result, very little is known about them, making them extremely attractive to researchers eager to learn about the mysterious species.
One of the biggest hurdles is keeping the host sea fans alive, since the pygmy sea horses cannot live without them. Biologists Matt Wandell and Rich Ross knew this would be tough, but they had been preparing since 2011 when Bart Shepherd, Director of the Steinhart Aquarium, issued them a challenge. They were tasked with keeping the sea fans alive for three years before they could even attempt bring back the seahorses. More »