Quantcast
Connect with us

Yes, giant predatory worms really are invading France

Published

on

This article is published in collaboration with researchers from the ISYEB (Institut de Systématique, Évolution, Biodiversité, Muséum national d’Histoire naturelle, Sorbonne Universités). Each month, they publish an article describing new species and cataloguing living organisms.


One of the consequences of globalisation and increased international trade in goods is the introduction of invasive species. In France, we have seen recently the arrival and proliferation of the “devil bug”, the Asian hornet and the Siberian chipmunk, as well as land flatworms such as Platydemus manokwari (from New Guinea) and Obama nungara (from South America).

ADVERTISEMENT

These flatworms, which move from continent to continent as plants and soil are transported, are generally of modest size, about 5 cm long – they can be held in the hand, although it is a bad idea to touch them. Among them, however, is a group of “giant” species, all of which have a “hammerhead”: the bipaliines, belonging to the genera Bipalium and Diversibipalium. The largest can reach 1 metre in length, and are mostly from Asia.

40 centimetres long

Our team has just published the results of five years of work with the help of citizen scientists, who sent us photographs and also specimens. More than 700 reports of land flatworms were received, of which more than 100 were bipaliines. Two of the species present in France, and sometimes very abundant, can reach 40 cm long. Think about this before you continue: if you’re reading this article on your laptop, 40 cm is easily longer than your screen is wide…

The head of Diversibipalium multilineatum. This species can reach 40 cm in length.
Pierre Gros, CC BY

Land flatworms consume soil fauna and pose a threat to soil biodiversity and ecological balance. Species of Bipalium feed on earthworms, and are able to kill and eat prey much larger than themselves. To do so, the Bipalium have a chemical armament including tetrodotoxin, one of the most powerful neurotoxins in the world, a thousand times more so than cyanide. Tetrodotoxin is the weapon of choice of the fugu, the poisonous fish beloved in Japan and eaten very carefully.

While our survey of land flatworms was originally intended only for mainland France, we received reports from the French overseas territories of Guadeloupe, Martinique, Saint Martin, Saint Barthélemy, French Guiana, Réunion, Mayotte and Polynesia, as well as from countries such as Switzerland, Monaco and Portugal. Unexpectedly, some of the citizens’ testimonials date back 20 years, as volunteers sent us older photographs and even videos from as far back to 1999.

Pictures of worms sent by citizen scientists.
Jean-Lou Justine, CC BY

In France, the two dominant species are Bipalium kewense and Diversibipalium multilineatum, which can reach 40 cm in length. Curiously, Bipalium kewense was also found in Guadeloupe, Martinique and French Guiana. A relatively small species, Bipalium vagum, has been found in several islands of the West Indies, French Guiana and Reunion, but not in metropolitan France. An unknown species, “black” Diversibipalium, was found in France, in a single location. A probably new species, “blue” Diversibipalium, was found only in Mayotte; this species is particularly spectacular with its iridescent turquoise colour.

ADVERTISEMENT

‘Blue’ Diversibipalium, found only in Mayotte.
Laurent Charles, CC BY

The Pyrénées-Atlantiques, a small paradise for giant worms…

In France itself, most of the bipaliines were found in the south, but very curiously, almost half of the reports come from a single department: the Pyrénées-Atlantiques, especially in the coastal area between Bayonne and the Spanish border. Land flatworms, which come from the semitropical regions of Asia, have two enemies: cold in winter and drought in summer. It seems that the Pyrénées-Atlantiques, with their mild winters and never-quite-dry summers, are a little paradise for them.

Reports of bipaliines in mainland France, obtained thanks to citizen scientists.
Jessica Thévenot, CC BY

Our molecular studies show that species found in several localities around the world are perfectly homogeneous from a genetic point of view, even when the specimens come from several continents. These species do not practice sexual reproduction and each individual is therefore a clone of its parent: a small piece detaches from the posterior part of the animal and turns into an adult, a phenomenon called fission. Asexual reproduction is a way for an alien species to quickly invade a territory. It also means that every worm is, in a sense, potentially immortal.

Scientists should be concerned

When we started working on this initiative in 2013, we did what every scientist does at the beginning of a new project – we looked for articles written by other scientists on the subject. To our astonishment, we found almost nothing on this subject in France, even though the invasion began more than 20 years ago. It seems paradoxical that the invasion of Europe by spectacular and highly visible animals that are also potentially dangerous for biodiversity had not attracted the attention of any scientist or institution up to now.

ADVERTISEMENT

Bipalium vagum, present in most French territories in the tropics, photographed here in French Guiana.
Sébastien Sant, CC BY

Citizens sometimes told us about their having brought specimens to research centres or universities only to have their fanciful identifications dismissed out of hand (“These are nothing but leeches, not interesting at all”). It is clear that efforts need to be made to better educate not only the public, but also scholars about the land flatworms. That said, those who couldn’t identify them 20 years ago had an excuse – they weren’t there.

The results of our study have been published in English, as is the general practice in science these days. To inform the public in France and its overseas territories, we have also written a full version in French of our article on the bipaliines, as we did, in 2013, for the arrival of Platydemus manokwari. Now, no more excuses!

ADVERTISEMENT

The ConversationAnd what of France’s European neighbour, the United Kingdom? Has it been spared from such invaders? Well, yes… and no. There are not yet any reports of the giant Bipalium or Diversibipalium flatworms in British gardens, the weather likely being too cold for these semitropical animals. But one species features a scientific name with a very English origin, Bipalium kewense – in Latin it means “from Kew”, because it was described in 1878 from specimens found in a hothouse of the Kew botanical gardens, near London. So there are giant flatworms present, but probably only in the hothouses. Other invasive flatworms have made the UK their home, however, including the New Zealand flatworm, Arthurdendyus triangulatus, which has decimated native earthworms since the 1980s. Adding insult to injury, the British Isles are the only place in Europe where this highly destructive species is established.

Jean-Lou Justine, Professeur de parasitologie, Muséum national d’histoire naturelle (MNHN) – Sorbonne Universités

This article was originally published on The Conversation. Read the original article.

ADVERTISEMENT


Report typos and corrections to: [email protected].
READ COMMENTS - JOIN THE DISCUSSION
Continue Reading

Breaking Banner

Trump’s claim impeachment ‘nullifies’ 2016 election blown up in new House Judiciary Committee report

Published

on

On Saturday, the House Judiciary Committee released their report outlining the offenses committed by President Donald Trump, and the legal framework for impeachment — which clears the way for Congress to write and approve articles of impeachment against him.

One of the key issues examined by the report is the claim, repeatedly made by the president and his supporters, that impeachment would "nullify" the 2016 presidential election and the popular will — which is already a weak claim given that Trump never won the popular vote, and that impeaching Trump would still install Mike Pence as president. But the report more broadly rejects the entire claim that an election result immunizes a president from punishment for official misconduct.

Continue Reading

Breaking Banner

READ IT: House Judiciary Committee releases report defining Trump impeachable offenses

Published

on

On Saturday, the House Judiciary Committee released a report outlining the impeachable acts committed by President Donald Trump.

"Our President holds the ultimate public trust," said the report, titled "Constitutional Grounds for Presidential Impeachment," in its introduction. "A President faithful only to himself—who will sell out democracy and national security for his own personal advantage—is a danger to every American. Indeed, he threatens America itself."

The report clarifies the procedures for impeachment, analyzes whether president can be "impeached for abuse of executive powers," and "whether it is preferable to await the next election when a President has sought to corrupt that very same election."

Continue Reading
 

Facebook

Devin Nunes likely under federal investigation over foreign contacts after Parnas phone call revelation: ex-FBI official

Published

on

On MSNBC's "AM Joy," former FBI Assistant Director for Counterintelligence Frank Figliuzzi speculated that Rep. Devin Nunes (R-CA) may already be under FBI investigation for his secret calls with indicted Rudy Giuliani associate Lev Parnas.

"What do you make of the fact that the ranking member on the House Intelligence Committee, who participated in the Adam Schiff portion of the impeachment hearings, never said anything to anybody about the fact that he was not just the guy who's sitting on the dais, he was involved in some way with one of the players?" asked host Joy Reid.

"Well, it says a lot on two levels," said Figliuzzi. "It says a lot about Devin Nunes as an individual, his ethics, his integrity, and what he's all about. And then on a larger level, it's just a huge, ironic development that we're hearing all of this about — the Republicans are defending allegations that the president lacks integrity and ethics, and they're sitting there overseeing this and they're not recusing themselves, and they're not saying anything about their colleague, Devin Nunes. So, you know, the hypocrisy is loud and clear here. And eventually when the dust clears, Joy, I wouldn't be surprised if ethics investigations and perhaps even criminal investigations really point the finger at Nunes as someone who should have recused himself and is much deeper into this than we know now."

Continue Reading