James' World 2

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Octopus sex hinges on a peculiar anatomical trick. In lieu of a penis, the male has a special mating arm called a hectocotylus. He feels around with it inside the female’s mantle—the bulbous structure behind the eyes that houses all of an octopus’s organs, including reproductive ones—until he finds her ovaries. He then slides a sac of sperm down his arm and deposits it. But the male can’t actually see what he’s doing. So how does he know when he’s found the right spot to send in the sperm? The answer, it turns out, lies in the arm itself.

In a new study published today in Science, researchers show that the male octopus’s mating arm can sense a female’s sex hormones emanating from the oviduct.

The suckers on octopus arms are equipped with chemotactile receptors that allow them to “taste” their surroundings through touch. But octopuses don’t typically use the hectocotylus in hunting or seafloor exploration—instead, males hold it close to their bodies when they’re not mating. Nevertheless, this appendage, like the other seven, comes loaded with receptors, says Pablo Villar, a postdoctoral fellow at Harvard University and co-lead author of the new paper.

To understand what purpose these receptors might serve, Villar and his colleagues coaxed a pair of California two-spot octopuses to mate in the lab. Because octopuses can be aggressive, the researchers installed a divider in the tank with a few small holes so the pair could warm up to each other. This arrangement might seem ill-suited for lovemaking, but surprisingly, the male simply reached across the barrier and got busy. The researchers tested four more mating pairs and got the same result—even in total darkness. “They made it seem super, super natural,” Villar says.

Octopuses are highly visual creatures who communicate through body language and color changes. But these flourishes don’t seem essential for mating. “They were able to do it with no visual cues,” Villar says, “just by touching.” Female octopuses, he and his team theorized, must release some kind of chemical signal to guide males in.

They found that the octopus oviduct produces enzymes that are used to make the sex hormone progesterone. This hormone seems to be what gets the hectocotylus going: when the researchers attached tubes to the holes in the tank divider, each coated with a different chemical, males were quickly drawn to the one containing progesterone. Even amputated mating arms behaved the same way, responding to progesterone but not to other molecules.

Many animals rely to some extent on detecting sex hormones to mate. But the organ that senses those hormones is usually separate from the one that delivers the sperm; in male octopuses, the hectocotylus does both. That way, says Nicholas Bellono, a molecular biologist at Harvard University and Villar’s postdoctoral advisor, “you make sure at the site of release that that’s the exact spot.”

Females of different octopus species may have unique chemical signatures, and males’ receptors may be tuned to respond only to the right blend of hormones. If so, this mating strategy could help keep species separate and potentially give rise to new ones. “Species boundaries are shaped not only by the genes organisms carry, but by the molecular systems that determine how organisms perceive one another,” Anna Di Cosmo, a zoologist at the University of Naples Federico II, wrote in a commentary accompanying the new study. “By reshaping perception, evolution reshapes reproduction, which reshapes the tree of life.”

Elena Gracheva, a neurophysiologist at Yale University, who was not involved in the new study, says it’s too soon to tell whether all octopuses mate in this way or what role these sensory systems may play in evolution. She is impressed by the thoroughness of the research, however, which began with a naturalistic observation and proceeded all the way to fine-grained molecular analyses. “You have very striking animal behavior, and then you’re going down to the single molecule, which I think is beautiful,” she says. “But I would say that this is just the beginning of the discovery.”

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What we know so far

• US aircraft downed: The status of a US service member remains unknown after an F-15 fighter jet was shot down over Iran. The jet’s other crew member was rescued, US sources told CNN. Iran also struck a second US military plane Friday, forcing the pilot to eject outside Iranian territory, according to a US official.

• Iran offers reward: Tehran has claimed responsibility for shooting down the F-15 and has promised a reward if Iranians find and hand over an American service member.

• In Washington, DC, President Donald Trump still has not publicly commented on the search and rescue mission for the downed crew member. He said in an interview Friday that the jet’s downing would not affect Iran war negotiations.

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Hmmmm … Very short view!

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TNASA executed several engine firings on Thursday. The apogee raise burn sent Orion into high-Earth orbit, where the backdrop offered a striking view of the planet. (Source: NASA, speed-increased)

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A striking view of the planet Earth

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Pete Hegseth, the U.S. defense secretary, has asked the American people to pray “every day, on bended knee” for a military victory in the Middle East “in the name of Jesus Christ.”

Pope Leo XIV, the first U.S.-born pontiff, has a starkly different take on what should be done in Jesus’s name.

In a homily during a Mass on Thursday morning before Easter, the pope said that the Christian mission has often been “distorted by a desire for domination, entirely foreign to the way of Jesus Christ.”

Since the United States and Israel began bombing Iran in late February, the pope has consistently called for an end to the violence and a return to dialogue to resolve the conflict. But without naming Mr. Hegseth, he has also pointed out the ways in which Christianity has been marshaled for purposes that the pope says do not align with Catholic teaching.

“We tend to consider ourselves powerful when we dominate, victorious when we destroy our equals, great when we are feared,” the pope said in a homily during a Holy Thursday rite at the Basilica of St. John Lateran, the cathedral of the bishop of Rome. “God has given us an example — not of how to dominate, but of how to liberate; not of how to destroy life, but of how to give it.”

In late March, the pope warned against invoking the name of Jesus for battle, saying in a Sunday homily that Jesus “does not listen to the prayers of those who wage war, but rejects them.”

Throughout his first year as pontiff, Leo has been careful not to wade into U.S. politics and has avoided direct confrontation with the White House.

He has used his influence through proxies, such as when he encouraged U.S. bishops to strongly support immigrants last year as President Trump escalated his deportation campaign.

He has mentioned Mr. Trump only when asked directly by a reporter if he had a message for the U.S. president.

“I’m told that President Trump recently stated that he would like to end the war,” the pope said outside his country residence in Castel Gandolfo outside Rome on March 31. “Hopefully he’s looking for a way to, to decrease the amount of violence, of bombing.”

Pope Leo has said he has not spoken directly to Mr. Trump about the war. But he talked Friday morning by telephone with Isaac Herzog, president of Israel, and reiterated the importance of dialogue and ending the conflicts to secure a “just and lasting peace” in the Middle East, according to a Vatican statement.

More on the Fighting in the Middle East

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• Strait of Hormuz: Britain announced it would hold talks with military planners around the globe about securing the strait for shipping. Separately, Russia, China, and France effectively stymied a push by Arab countries to get the U.N. Security Council to authorize military action against Iran to reopen it.

• Iranian Bridge: President Trump celebrated a strike on a highway bridge near Tehran and warned there was “much more to follow.” Iran state media said eight people had been killed in the attack and dozens wounded.

• Attacks on Infrastructure: In Kuwait, an attack damaged a power and water desalination plant. Kuwait blamed Iran, which denied carrying out the attack.

• The Iranian Diaspora: Divided by war in their native country, Iranians living abroad are navigating broken relationships and lost friendships.

• Mood in Israel: A majority of Israelis support the war with Iran, but many doubt that it will solve Israel’s long-term security problems. Some also question their prime minister’s assurances and motives.

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Pope Leo, during the Holy Thursday Mass in Rome, said the Christian mission had often been “distorted by a desire for domination.” Credit…Vincenzo Livieri/Reuters

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