The Astonishing Sex Lives Of Slugs

Two "banana slugs" curling up...
Two "banana slugs" curling up...
Kerstin Viering

BERLIN - Chances are, you don't know anyone with professional interests quite like biologist Heike Reise. She and her colleagues at Germany's Senckenberg Museum of Natural History in Görlitz are studying the sex life of slugs, also known as "naked snails" for their lack of shells.

Every year the scientists catch and observe primarily field slugs (genus Deroceras), which apparently have a richly eccentric sex life, even by snail standards.

The researchers leave the slugs — hermaphrodites possessed of both male and female sex organs — on their own for a few days in individual receptacles. "After about a week they’re ready to mate," Reise says. The scientists record their activity on camera. They put two slugs together and film their sexual activity from various angles in red light. "The snails can’t see this, so they are not disturbed," Reise explains.

Such research on the molluscs would hardly be possible without filming because while snails are not known for their swiftness in general, there is nothing sluggish about their sex lives. They spend hours engaged in foreplay, but the act of sex is very quick. A penis will suddenly emerge, and it takes less than a second to ejaculate. Way too fast, in other words, for the eyes of curious researchers -- so video makes it possible "to analyze exactly the interaction of the genitalia," Reise says.

What the sex tapes reveal depends very much on the snails themselves. It appears that each of the 100 or so presently known field slug species has its own sexual preferences, "and these behaviors are so typical that you can tell the different species apart by whichever behavior they exhibit," says Reise.

This is particularly helpful because field slugs are otherwise difficult to distinguish. There are differences of size and color, but both can vary widely within the same species. It’s more conclusive to examine their penises, which differ in build depending on the species, although even this doesn’t necessarily guarantee accurate identification. That's why researchers analyze coupling behaviors.

Reise and her colleagues have already been able to identify several as yet unidentified slug species. One of these successes involves a slug that can now be found all over the world and that has made itself a very unpopular pest in vegetable patches. For a long time scientists thought this was the Deroceras panormitanum, originally from southern Italy, but a few were starting to suspect that several species were being mistaken for them. But few were absolutely certain — until Reise and her colleagues came along and discovered that the coupling behaviors of the southern Italian slugs were massively different from those of the cosmopolitan pest now known as Deroceras invadens.

Using genetic markers, the Senckenberg researchers intend next to tackle the question of whether all the vegetable-eating pests in the world belong to this new species or whether there are in fact more unidentified species out there. Reise and colleagues are also hoping their research will yield answers to how the slugs proliferate, why they are so successful, and how to better combat them.

Fascinating — and a little kinky

But the motivating force of snail sex research for many scientists is sheer curiosity, and astonishment, at the bizarre ways of nature. They can only shake their heads in wonder at the love games of the great, grey slug Limax maximus, for example. During copulation, these 10- to 20-centimeter-long slugs twine themselves around each other as they hang from a tree and create a spiral with their intertwined penises, transferring sperm from tip to tip.

Two Limax Maximus slugs mating - Photo: John from Tulsa

For other slug species, coupling can be even more challenging. The black Limax cinereoniger is a case in point. It can take them up to 20 minutes to get their 10-centimeter penises untangled. Then there are the problems encountered by Limax redii, native to the southern Alps, which has a penis anywhere from 15 to 85 centimeters long. Yet they somehow manage to untangle themselves after sex.

The North American yellow banana slug (Ariolimax) doesn’t always manage, however, to withdraw its penis out of the female sex organ, and when that happens at least two species take drastic measures: they either bite their own penis off, or let their partner do it, and then go on to live out the rest of their days as a female. But scientists have also recorded such amputations when there was technically no need for them, and they want to discover the reasons why.

Other snail species have a predilection for rough sex, where one partner gets hurt. These include Helix pomatia (variously called the Burgundy snail, Roman snail or escargot), which actually rams a harpoon-like love dart into its partner’s body.

Researchers have pondered the function of this sharp calcareous weapon for years. It is now clear that it is an injection of a hormone-like secretion to facilitate the path of sperm to egg. A practice that plays a major role in the love games of Deroceras species — whereby one partner secretes a substance onto the back of the other after the sex act — could have a similar function, Reise and colleagues believe. "We think field slugs are manipulating their partners hormonally to make sure that the offspring is theirs,” she says.

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Queen Elizabeth II with UK PM Boris Johnson at a reception at Windsor Castle yesterday

Anne-Sophie Goninet, Jane Herbelin and Bertrand Hauger

👋 Hej!*

Welcome to Wednesday, where chaos hits Syria, Brazilian president Jair Bolsonaro is accused of crimes against humanity and a social media giant plans to rebrand itself. For Spanish daily La Razon, reporter Paco Rodríguez takes us to the devastated town of Belchite, where visitors are reporting paranormal phenomenons.



• Syrian violence erupts: Army shelling on residential areas of the rebel-held region of northwestern Syria killed 13 people, with school children among the victims. The attack occurred shortly after a bombing killed at least 14 military personnel in Damascus. In central Syria, a blast inside an ammunition depot kills five soldiers.

• Renewed Ethiopia air raids on capital of embattled Tigray region: Ethiopian federal government forces have launched its second air strike this week on the capital of the northern Tigray. The air raids mark a sharp escalation in the near-year-old conflict between the government forces and the Tigrayan People's Liberation Front (TPLF) that killed thousands and displaced over 2 million people.

• Bolsonaro accused of crimes against humanity: A leaked draft government report concludes that Brazilian President Jair Bolsonaro should be charged with crimes against humanity, forging documents and incitement to crime, following his handling of the country's COVID-19 pandemic. The report blames Bolsonaro's administration for more than half of Brazil's 600,000 coronavirus deaths.

• Kidnappers in Haiti demand $17 million to free a missionary group: A Haitian gang that kidnapped 17 members of a Christian aid group, including five children, demanded $1million ransom per person. Most of those being held are Americans; one is Canadian.

• Putin bows out of COP26 in Glasgow: Russian President Vladimir Putin will not fly to Glasgow to attend the COP26 climate summit. A setback for host Britain's hopes of getting support from major powers for a more radical plan to tackle climate change.

• Queen Elizabeth II cancels trip over health concerns: The 95-year-old British monarch has cancelled a visit to Northern Ireland after she was advised by her doctors to rest for the next few days. Buckingham Palace assured the queen, who attended public events yesterday, was "in good spirits."

• A new name for Facebook? According to a report by The Verge website, Mark Zuckerberg's social media giant is planning on changing the company's name next week, to reflect its focus on building the "metaverse," a virtual reality version of the internet.


"Oil price rise causes earthquake," titles Portuguese daily Jornal I as surging demand coupled with supply shortage have driven oil prices to seven-year highs at more than $80 per barrel.



For the first time women judges have been appointed to Egypt's State Council, one of the country's main judicial bodies. The council's chief judge, Mohammed Hossam el-Din, welcomed the 98 new judges in a celebratory event in Cairo. Since its inception in 1946, the State Council has been exclusively male and until now actively rejected female applicants.


Spanish civil war town now a paranormal attraction

Ghosts from Spain's murderous 1930s civil war are said to roam the ruins of Belchite outside Zaragoza. Tourists are intrigued and can book a special visit to the town, reports Paco Rodríguez in Madrid-based daily La Razon.

🏚️ Between August 24 and September 6, 1937, during the Spanish Civil War, more than 5,000 people died in 14 days of intense fighting in Belchite in north-eastern Spain, and the town was flattened. The fighting began on the outskirts and ended in house-to-house fighting. Almost half the town's 3,100 residents died in the struggle. The war annihilated centuries of village history. The town was never rebuilt, though a Pueblo Nuevo (or new town) was built by the old one.

😱 Belchite became an open-air museum of the horror of the civil war of 1936-39, which left 300,000 dead and wounds that have yet to heal or, for some today, mustn't. For many locals, the battle of Belchite has yet to end, judging by reports of paranormal incidents. Some insist they have heard the screams of falling soldiers, while others say the Count of Belchite wanders the streets, unable to find a resting place after his corpse was exhumed.

🎟️ Ordinary visitors have encountered unusual situations. Currently, you can only visit Belchite at set times every day, with prior booking. More daring visitors can also visit at 10 p.m. on weekends. Your ticket does not include a guaranteed paranormal experience, but many visitors insist strange things have happened to them. These include sudden changes of temperature or the strange feeling of being observed from a street corner or a window. Furthermore, such phenomena increase as evening falls, as if night brought the devastated town to life.

➡️ Read more on Worldcrunch.com


We still cling to the past because back then we had security, which is the main thing that's missing in Libya today.

— Fethi al-Ahmar, an engineer living in the Libyan desert town Bani Walid, told AFP, as the country today marks the 10-year anniversary of the death of dictator Muammar Gaddafi. The leader who had reigned for 42 years over Libya was toppled in a revolt inspired by the Arab Spring uprisings and later killed by rebels. Some hope the presidential elections set in December can help the country turn the page on a decade of chaos and instability.


Iran to offer Master's and PhD in morality enforcement

Iran will create new "master's and doctorate" programs to train state morality agents checking on people's public conduct and attire, according to several Persian-language news sources.

Mehran Samadi, a senior official of the Headquarters to Enjoin Virtues and Proscribe Vices (Amr-e be ma'ruf va nahy az monkar) said "anyone who wants to enjoin virtues must have the knowledge," the London-based broadcaster Iran International reported, citing reports from Iran.

The morality patrols, in force since the 1979 revolution, tend to focus mostly on young people and women, particularly the public appearance for the latter. Loose headscarves will send women straight to a police station, often in humiliating conditions. Five years ago, the regime announced a new force of some 7,000 additional agents checking on women's hijabs and other standards of dress and behavior.

Last week, for example, Tehran police revealed that they had "disciplined" agents who had been filmed forcefully shoving a girl into a van. Such incidents may increase under the new, conservative president, Ibrahim Raisi.

Speaking about the new academic discipline, Samadi said morals go "much further than headscarves and modesty," and those earning graduate degrees would teach agents "what the priorities are."

Iran's Islamic regime, under the guidance of Shia jurists, continuously fine tunes notions of "proper" conduct — and calibrates its own, interventionist authority. More recently the traffic police chief said women were not allowed to ride motorbikes, and "would be stopped," Prague-based Radio Farda reported.

Days before, a cleric in the holy city of Qom in central Iran insisted that people must be vaccinated by a medic of the same sex "as often as possible," and if not, there should be no pictures of mixed-sex vaccinations.

✍️ Newsletter by Anne-Sophie Goninet, Jane Herbelin and Bertrand Hauger

Thoughts on Facebook's new name? Zuckerverse? Tell us how the news look in your corner of the world: Drop us a note at info@worldcrunch.com!

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