Weird worms top 5

This 11 June 2020 video says about itself:

There are some very strange worms inhabiting our planet – here are 5 of the weirdest.

New deep-sea worm species’ Elvis Presley name

By Maria Temming, May 25, 2020 at 6:00 am:

New species of scaly deep-sea worms named after Elvis have been found

The animals’ iridescent scales are reminiscent of sequins on the iconic jumpsuits of ‘The King’

A new look at the critters known as “Elvis worms” has the scale worm family all shook up.

These deep-sea dwellers flaunt glittery, iridescent scales reminiscent of the sequins on Elvis’ iconic jumpsuits (SN: 1/23/20). “For a while, we thought there was just one kind of Elvis worm,” says Greg Rouse, a marine biologist at the Scripps Institution of Oceanography in La Jolla, Calif. But analysis of the creatures’ genetic makeup shows that Elvis worms comprise four species of scale worm, Rouse and colleagues report May 12 in ZooKeys.

Rouse’s team compared the genetic material of different Elvis worms with each other, and with DNA from other scale worm species. This analysis places Elvis worms in the Peinaleopolynoe genus of scale worms, which includes two other known species — one found off the coast of Spain, the other off California.

This 21 May 2020 video says about itself:

Deep-sea ‘Elvis worms’ show off their sequin like scales | Science News

A new genetic analysis of the deep-sea creatures nicknamed “Elvis worms” reveals that these iridescent creatures include four separate species. The Elvis worms seen in this video belong to the species Peinaleopolynoe orphanae, which mostly sport glittery blue scales, but also come in other colors, like black and red. These worms may look dainty, but they fight dirty, chomping at each other’s scales when they get into skirmishes.

The Maria Temming article continues:

The four newly identified Elvis worm species are scattered across the Pacific, from P. elvisi and P. goffrediae in Monterey Canyon off California to P. orphanae in the Gulf of California by Mexico and P. mineoi near Costa Rica.

These deep-sea Elvis impersonators share some common traits, such as nine pairs of scales. But each species has its own distinct flare. P. elvisi’s gold and pink iridescent color scheme earned it the honor of keeping the worms’ namesake in its official title. P. orphanae, on the other hand, mostly sports rainbow-sparkled scales of a bluish hue.

The researchers don’t know why Elvis worms have evolved such eye-catching scales, since the animals live in the dark, deep sea. It could just be a side effect of developing thicker scales over time, which happen to refract more light, Rouse says. Thicker scales could come in handy in a fight, since Elvis worms are apparently biters, a behavior discovered while watching a worm skirmish. “Suddenly, they started doing this amazing jitterbugging — wiggling, and then fighting and biting each other” on their scales, Rouse says. “No one’s ever seen any behavior like this in scale worms.”

Ancient Cambrian worm, new genus discovery

From the University of Kansas in the USA:

Mysterious ancient sea-worm pegged as new genus after half-century in ‘wastebasket’

March 17, 2020

Summary: Fifty years ago, researchers placed a mystery worm in a ‘wastebasket‘ genus and interest in the lowly critter waned — until now.

When a partial fossil specimen of a primordial marine worm was unearthed in Utah in 1969, scientists had a tough go identifying it. Usually, such worms are recognized and categorized by the arrangement of little knobs on their plates. But in this case, the worm’s plates were oddly smooth, and important bits of the worm were missing altogether.

Discouraged, researchers placed the mystery worm in a “wastebasket” genus called Palaeoscolex, and interest in the lowly critter waned for the next 50 years.

That all changed recently when Paul Jamison, a teacher from Logan, Utah, and private collector, and his student Riley Smith were hunting fossils in the Spence Shale in Utah, a 506-million-year-old geologic unit housing a plethora of exceptionally preserved soft-bodied and biomineralized fossils. (Paleontologists call such a mother lode of fossils a “Lagerstätte.”) There, Smith discovered a second, more thoroughly preserved example of the worm.

Eventually, thanks to Jamison’s donation, the new fossil specimen arrived at the University of Kansas Biodiversity Institute, where Anna Whitaker, a graduate student in museum studies, researched and analyzed the worm with scanning electron microscopes, energy-dispersive X-ray spectrometry and optical microscopy.

At last, Whitaker determined the worm represented a new genus of Cambrian sea worm heretofore unknown to science. She’s the lead author of a description of the worm just published in the peer-reviewed paleontological journal PalZ.

“Before the new species that we acquired there was only one specimen known from the Spence Shale”, she said. “But with our new specimen we discovered it had characteristics that the original specimen didn’t have. So, we were able to update that description, and based on these new characteristics — we decided it didn’t fit in its old genus. So, we moved it to a new one.”

Whitaker and her colleagues — Jamison, James Schiffbauer of the University of Missouri and Julien Kimmig of KU’s Biodiversity Institute — named the new genus Utahscolex.

“We think they’re closely related to priapulid worms that exist today — you can find them in the oceans, and they are very similar to priapulids based on their mouthparts,” Whitaker said. “What’s characteristic about these guys is that they have a proboscis that can evert, so it can turn itself inside out and it’s covered with spines — that’s how it grabs food and sucks it in. So, it behaved very similarly to modern priapulid worms.”

While today, Utah is not a place you’d look for marine life, the case was different 506 million years ago, when creatures preserved in the Spence Shale were fossilized.

“The Spence Shale was a shelf system, and it’s really interesting because it preserves a lot of environments — nearshore to even deeper offshore, which is kind of unusual for a Lagerstätte, and especially during the Cambrian. These animals were living in kind of a muddy substrate. This worm was a carnivore, so it was preying on other critters. But there would have been whole diversity of animals — sponges, and trilobites scuttling along. We have very large, for the time, bivalve arthropods that would be predators. The Spence has a very large diversity of arthropods. It would have looked completely alien to us today.”

Whitaker hopes to complete her master’s degree this spring, then to attend the University of Toronto to earn her doctorate. The description of Utahscolex is Whitaker’s first academic publication, but she hopes it won’t be her last. She said the opportunity to perform such research is a chief reason for attending KU.

“I came for the museum studies program,” she said. “It’s one of the best in the country, and the program’s flexibility has allowed me to focus on natural history collections, which is what I hopefully will have a career in, and also gain work experience in the collections and do research — so it’s kind of everything I was looking for in the program.”

While ancient sea worms could strike many as a meaninglessly obscure subject for such intense interest and research, Whitaker said filling in gaps in the fossil record leads to a broader understanding of evolutionary processes and offers more granular details about the tree of life.

“I know some people might say, ‘Why should we care about these?'” she said. “But the taxonomy of naming all these species is really an old practice that started in the 1700s. It underpins all the science that we do today. Looking at biodiversity through time, we have to know the species diversity; we have to know as correctly as we can how many species there were and how they were related to each other. This supports our understanding of — as we move into bigger and bigger, broader picture — how we can interpret this fossil record correctly, or as best we can.”

Seven new leech species discovered

This 2017 video is called North American leeches, “Macrobdela decora“.

From the North Carolina Museum of Natural Sciences in the USA:

Gimme shelter: Seven new leech species call freshwater mussels home

November 11, 2019

The frequent presence of leeches with a hidden lifestyle in the mantle cavity of freshwater mussels has been recorded since the second half of the 19th century. Yet this was, until now, regarded as an accidental phenomenon. Recent research not only reveals seven mussel-associated leech species new to science, but also shows that their association evolved over millions of years.

The diverse ecological group of leeches were found inside more than 3,000 freshwater mussels collected (by numerous collaborators) from East Asia, Southeast Asia, India and Nepal, Africa and North America between 2002 and 2018. Arthur Bogan, Research Curator of Mollusks for the North Carolina Museum of Natural Sciences, was part of the massive collecting effort and focused his search on parts of eastern Russia (Vladivostok area), Japan and Myanmar.

The study’s novel data reveals that at least two groups of mussel-associated leech species could be considered obligate inhabitants of the mantle cavity of freshwater mussels, meaning they cannot complete their lifecycle without exploiting their host. How did this come about? According to lead author Ivan N. Bolotov of the Federal Center for Integrated Arctic Research of the Russian Academy of Sciences, “It has been suggested that the primary selective pressure driving the evolution of parental care in leeches may have been predation on leech eggs and juvenile stages. From this point of view, [this lifestyle] could be considered a progressive evolutionary trait in brooding behavior helping to protect juvenile stages from predators.

“To estimate divergence times for mussel-associated leech clades, we calculated the first fossil-calibrated global phylogeny of leeches using a fossil leech cocoon from mid-Triassic lacustrine deposits in Antarctica as a calibration. It was found that leeches are slowly evolving animals as several other ‘living fossil’ taxa, for example, freshwater mussels, coelacanths, anthozoans, sturgeons and puddle fishes [sic; paddlefishes]. The reliable mutation rates obtained by us are of great importance to future evolutionary studies of these worms.”

The study also showed that even these leech species are not permanent residents. Molecular studies of the digestive system content of the adult mussel-associated leeches indicate that they leave their mussel hosts periodically to obtain blood of freshwater fishes. Probably, adult leeches need to use one or several higher-calorie fish blood meals instead of nutritionally sparse mussel haemolymph (body fluids of invertebrates) to ensure the successful development of eggs and complete their life cycle. While larvae and juvenile mussel-associated leeches could feed on mucus and body fluids of freshwater mussels.

Such a two-host feeding behavior, when fish blood meals are needed at the final stage of the lifecycle just before leech reproduction, appears to be a successful adaptation to a freshwater environment, in which availability of vertebrate blood is limited, and many leech species are forced to use nutrient-poor haemolymph as the primary feeding source.

The discovery of this mussel-leech association has wider-ranging importance because freshwater mussels are one of the most imperiled animal groups worldwide, revealing the fastest rates of extinction. Habitat degradation, river pollution and climate change are the primary causes of global decline. However, biological threats for freshwater mussels are still poorly known.

The findings were published in Scientific Reports in November.

Californian worm species with three sexes discovery

This April 2018 video from the USA says about itself:

Mono Lake is a striking blue oasis in the eastern California surrounded by desert peaks, volcanoes, and the Sierra Nevada. Strange tufa tower formations and saline waters lie at the edge of mountain streams and snow-capped mountains. Millions of birds, trillions of brine shrimp, and countless alkali flies contribute to one of the most productive lake ecosystems on the planet.

In 1941, the Los Angeles Department of Water & Power began the Mono Lake Storydiverting water from Mono Lake’s tributary streams, sending it 350 miles south to meet the growing water demands of Los Angeles. Deprived of its freshwater sources, the lake dropped 45 vertical feet. Its salinity doubled and the ecosystem approached collapse.

Researchers, students, bird freaks, and an engaged public took notice and formed the Mono Lake Committee. Sixteen Years later, this dedicated grassroots movement altered history by protecting Mono Lake, securing new water solutions for Los Angeles, and transforming water law in California. The Mono Lake Story is about changing values and balancing those values against difficult odds. It’s about how a small and dedicated group of individuals, trying to do the right thing, can grow into an effective coalition of organizations, agencies, and public support that triumph over fundamental environmental challenges.

The Mono Lake story is a rare environmental success that can inspire and inform the environmental challenges of our time.

From the California Institute of Technology in the USA:

Otherworldly worms with three sexes discovered in Mono Lake

Eight species of nematode discovered in the lake’s harsh conditions

September 26, 2019

Summary: The extreme environment of Mono Lake was thought to only house two species of animals — until now.

Caltech scientists have discovered a new species of worm thriving in the extreme environment of Mono Lake. This new species, temporarily dubbed Auanema sp., has three different sexes, can survive 500 times the lethal human dose of arsenic, and carries its young inside its body like a kangaroo.

Mono Lake, located in the Eastern Sierras of California, is three times as salty as the ocean and has an alkaline pH of 10. Before this study, only two other species (other than bacteria and algae) were known to live in the lake — brine shrimp and diving flies. In this new work, the team discovered eight more species, all belonging to a class of microscopic worms called nematodes, thriving in and around Mono Lake.

The work was done primarily in the laboratory of Paul Sternberg, Bren Professor of Biology. A paper describing the research appears online on September 26 in the journal Current Biology.

The Sternberg laboratory has had a long interest in nematodes, particularly Caenorhabditis elegans, which uses only 300 neurons to exhibit complex behaviors, such as sleeping, learning, smelling, and moving. That simplicity makes it a useful model organism with which to study fundamental neuroscience questions. Importantly, C. elegans can easily thrive in the laboratory under normal room temperatures and pressures.

As nematodes are considered the most abundant type of animal on the planet, former Sternberg lab graduate students Pei-Yin Shih (PhD ’19) and James Siho Lee (PhD ’19) thought they might find them in the harsh environment of Mono Lake. The eight species they found are diverse, ranging from benign microbe-grazers to parasites and predators. Importantly, all are resilient to the arsenic-laden conditions in the lake and are thus considered extremophiles — organisms that thrive in conditions unsuitable for most life forms.

When comparing the new Auanema species to sister species in the same genus, the researchers found that the similar species also demonstrated high arsenic resistance, even though they do not live in environments with high arsenic levels. In another surprising discovery, Auanema sp. itself was found to be able to thrive in the laboratory under normal, non-extreme conditions. Only a few known extremophiles in the world can be studied in a laboratory setting.

This suggests that nematodes may have a genetic predisposition for resiliency and flexibility in adapting to harsh and benign environments alike.

“Extremophiles can teach us so much about innovative strategies for dealing with stress,” says Shih. “Our study shows we still have much to learn about how these 1000-celled animals have mastered survival in extreme environments.”

The researchers plan to determine if there are particular biochemical and genetic factors that enable nematodes’ success and to sequence the genome of Auanema sp. to look for genes that may enable arsenic resistance. Arsenic-contaminated drinking water is a major global health concern; understanding how eukaryotes like nematodes deal with arsenic will help answer questions about how the toxin moves through and affects cells and bodies.

But beyond human health, studying extreme species like the nematodes of Mono Lake contributes to a bigger, global picture of the planet, says Lee.

“It’s tremendously important that we appreciate and develop a curiosity for biodiversity,” he adds, noting that the team had to receive special permits for their field work at the lake. “The next innovation for biotechnology could be out there in the wild. A new biodegradable sunscreen, for example, was discovered from extremophilic bacteria and algae. We have to protect and responsibly utilize wildlife.”

The paper is titled, “Newly Identified Nematodes from Mono Lake Exhibit Extreme Arsenic Resistance.” Shih and Lee are co-first authors on the study; Shih is now a postdoctoral fellow at Columbia University and Lee is now a postdoctoral fellow at The Rockefeller University. In addition to Shih, Lee, and Sternberg, other co-authors are Ryoji Shinya of Meiji University in Japan, Natsumi Kanzaki of the Kansai Research Center in Japan, Andre Pires da Silva of the University of Warwick in the UK, former Caltech Summer Undergraduate Research Fellow student Jean Marie Badroos now of UC Berkeley, and Elizabeth Goetz and Amir Sapir of the University of Haifa in Israel. Funding was provided by the Amgen Scholars Program, the Leverhulme Trust, and the Howard Hughes Medical Institute.

Green bomber worms, deep-sea video

From the Monterey Bay Aquarium Research Institute (MBARI) in the USA:

Green bomber worms (Swima spp.) have specialized organs that explode with a burst of green bioluminescence. This impressive display is likely used to startle predators while the animal makes a speedy getaway. They live just above the seafloor and are vigorous swimmers, able to maneuver both backwards and forwards.⁠
⁠
Each worm carries up to eight “bombs”. If they lose one, they can grow it back. The “bombs” may have been gills that evolutionarily transformed over time. Although these worms lack eyes, they have developed a novel bioluminescent defense mechanism. MBARI research has shown that approximately three quarters of the animals living in the dark ocean depths are capable of producing bioluminescence.⁠
⁠
Learn more about these amazing deep-sea worms here.

Video editor: Ted Blanco
Writer: Kyra Schlining
Production team: Nancy Barr, Nancy Jacobsen Stout, Heidi Cullen

Deep-sea scale worms, video

This 1 July 2019 video from the USA says about itself:

The ocean is bristling with scale worms

Scale worms are easily recognized by their large, fleshy scales and hundreds of dazzling bristles. Scale worms dominate the deep sea not only in terms of species numbers, but also in the variety of their shapes and sizes. Of the nearly 20,000 species of segmented worms known today, nearly 10 percent are scale worms. What makes this group of worms so successful?

Researchers at the Monterey Bay Aquarium Research Institute and the Smithsonian National Museum of Natural History are on the hunt to find out.

Scale worms are predators, continually searching the seafloor for their next meal. Interestingly, many deep-sea species are blind, and rely on long, finger-like sensory appendages to help them locate their prey and to give them early warning of predators. Some scale worms have developed symbiotic relationships with other animals like corals, sponges, and even other types of worms. These worms have relatively small sensory appendages. Presumably, they don’t need early warning systems for this sheltered, symbiotic lifestyle.

Investigating the diverse forms and behaviors of scale worms reveals the ways this particular group of segmented worms has been able to thrive in so many challenging habitats, including the deep sea.

Happy International Polychaete Day!

Script: Brett C. Gonzalez, Ali Kazerani, and Karen J. Osborn (Smithsonian Museum of Natural History) Narration: Ali Kazerani Video editing: Kyra Schlining Music: Clover_3 (YouTube Audio Library)

Ice worm discovery in Canada

This 2007 video from Alaska says about itself:

Ice Worms | National Geographic

Ambitious scientists go to extremes on a hunt for elusive creatures in Denali National Park.

From Washington State University in the USA:

Unlocking secrets of the ice worm

June 26, 2019

The ice worm is one of the largest organisms that spends its entire life in ice and Washington State University scientist Scot Hotaling is one of the only people on the planet studying it.

He is the author of a new paper that shows ice worms in the interior of British Columbia have evolved into what may be a genetically distinct species from Alaskan ice worms.

Hotaling and colleagues also identified an ice worm on Vancouver Island that is closely related to a separate population of ice worms located 1,200 miles away in southern Alaska. The researchers believe the genetic intermingling is the result of birds eating the glacier-bound worms (or their eggs) at one location and then dropping them off at another as they migrate up and down the west coast.

“If you are a worm isolated on a mountaintop glacier, the expectation is you aren’t going anywhere,” said Hotaling, a postdoctoral biology researcher. “But low and behold, we found this one ice worm on Vancouver Island that is super closely related to ice worms in southern Alaska. The only reasonable explanation we can think of to explain this is birds.”

Super cool organism

The ice worm resembles the common earthworm but is smaller and darker in color. What sets the ice worm apart from other members of the Mesenchytraeus genus is its ability to live its entire life in glacial ice.

Millions, perhaps hundreds of millions, of ice worms can be seen wriggling to the top of glaciers from the Chugach Mountains in southeast Alaska to the Cascade Volcanoes of Washington and Oregon during the summer months. In the fall and winter, ice worms subsist deep beneath the surface of glaciers where temperatures stay around freezing.

Hotaling’s interest in ice worms began back in 2009 while he was working as a mountaineering ranger on the high elevation slopes of Mt. Rainer. He was climbing at three in the morning when he noticed a lot of small, black worms crawling around on the surface of a glacier.

“I wasn’t even a biology undergraduate yet but I remember being so fascinated by the fact that there is this worm that can live in a glacier,” he said. “It is not a place where we think of life being able to flourish and these things can be present at like 200 per sq. meter, so dense you can’t walk without stepping in them.”

Hotaling eventually went back to school and earned a PhD in biology at the University of Kentucky where he studied how climate change is affecting mountain biodiversity.

In the summer of 2017, he finally got the opportunity to circle back and do some research on the ice worm when he arrived in Pullman to start a postdoc position in the laboratory of Associate Professor Joanna Kelley, senior author of the study who specializes in evolutionary genomics and extremophile lifeforms.

“In the Kelley lab, we study organisms that have evolved to live in places that are inhospitable to pretty much everything else,” Hotaling said. “Determining the evolutionary mechanisms that enable something like an ice worm to live in a glacier or bacteria to live in a Yellowstone hot spring is a really exciting way to learn about what is possible at the bounds of evolution. That’s where we are working now, understanding the evolution of ice worms.”

In the study

Hotaling and colleagues extracted and sequenced DNA from 59 ice worms collected from nine glaciers across most of their geographical range. Their analysis revealed a genetic divergence between populations of ice worms that are north and west and south and east of the Coast Mountains of British Columbia.

The researchers predict that this deeper split into two genetically distinct ice worm groups occurred as a result of glacial ice sheets contracting around a few hundred thousand years ago, isolating worms in the Pacific Northwest from their counterparts in Alaska.

The most surprising finding of the study was the discovery of a single ice worm on Vancouver Island that was closely related to a population of ice worms 1,200 miles away in Alaska.

“At first we thought there has to be some kind of error in the analysis or prep methods but upon further investigation we confirmed our initial results,” Hotaling said. “These are worms isolated on mountain tops and there is no explanation for how they covered that gap than on, or perhaps within, migrating birds.”

The research illuminates an important relationship between two of the few large organisms that inhabit North America’s high elevation alpine ecosystems, the ice worm and the Gray-Crowned Rosy Finch, one of North America’s highest elevation nesting birds.

“We knew that ice worms were an important source of food for the birds but we didn’t know until now that the birds are also likely very important for the ice worms,” Hotaling said. “If you are super isolated like an ice worm, you could easily become inbred. But if birds are bringing little bits of new diversity to your mountaintop glacier that could be really good for you.”

Hotaling and Kelley’s study was published this month in Proceedings of the Royal Society B.

New earthworm species discovery in the Netherlands

This 2012 video is called The Amazing World Of Earthworms In The UK – Springwatch – BBC Two.

Today, biologist Anne Krediet reported on Dutch Vroege Vogels radio about the discovery in Biesbosch national park of an earthworm species, new for the Netherlands. It is Murchieona muldadi.

It is a small species, only about 15-25 millimeter.

Krediet recently published this book about the about 30 earthworm species of the Netherlands.

New marine flatworm species discoveries

This 25 November 2018 video says about itself:

Colorful Marine Flatworms – 20 species / Turbellaria

Free-living marine flatworm (German: freilebende Meeresstrudelwürmer) are some of the most fascinating although simple creatures in the world´s oceans. The bright coloring advertises their toxicity to predators, making many species reasonably safe in open areas.

Aside from their toxins, flatworms have simple body structures. They have no respiratory or circulatory systems, so their bodies are a flat shape to allow for diffusion of carbon dioxide and oxygen. Their digestive system consists of a straightforward but many-branched intestine which allows nutrients to be spread throughout the body.

Marine flatworms are hermaphroditic, meaning they have both male and female reproductive organs.The life span of marine flatworms is generally between three weeks to three to four months long.

From Zootaxa, 12 April 2019:

Two new species of marine flatworm from southern China facilitate determination of the phylogenetic position of the genus Nerpa Marcus, 1948 and the histochemical structure of the nervous system in the genus Paucumara Sluys, 1989 (Platyhelminthes, Tricladida, Maricola)

IA-JIA CHEN, WEI-XUAN LI, RONALD SLUYS, MING-QI WU, LEI WANG, SHUANG-FEI LI, AN-TAI WANG

Abstract

Two new species of flatworm, collected from a beach at eastern Shenzhen, China, were studied through an integrative approach by combining morphological, histological, histochemical (acetylcholinesterase, AChE), and molecular (18S r- DNA) data. These species belong to two genera of marine triclads, previously unrecorded from China, viz. Nerpa Marcus, 1948 and Paucumara Sluys, 1989.

Nerpa fistulata Wang & Chen, sp. nov. is characterized by: transparent body; principally pentamerous intestine with three distinct commissures; two very large, prepharyngeal testis follicles; a semi-circular lens in each eye cup; a penis papilla provided with a chitinized, pointed stylet; lateral bursae communicating with the oviduct and opening ventrally to the exterior via a duct. Phylogenetically N. fistulata groups with one member of the family Bdellouridae. This new, Chinese species of Nerpa introduces a major geographic disjunction, as the type species N. evelinae was described from the bay of Santos, Brazil, so that the genus is now known from both Atlantic as well as Pacific coasts.

The species Paucumara falcata Wang & Li, sp. nov. is characterized by: three distinct pale yellow transverse pigmentation bands on its dorsal side, between which some snowflake-like specks are randomly distributed, and a brown transverse band anteriorly to the eyes; 8–11 testicular follicles on either side of the body, the follicles extending from immediately behind the ovaries to half-way along the pharyngeal pocket; a musculo-parenchymatic organ with a sclerotic, curved tip projecting from the anterior wall of the male atrium, ventrally to the root of the penis papilla. Phylogenetically P. falcata groups with its congener P. trigonocephala, with the genus Paucumara forming the sister taxon of the genus Ectoplana. Comparison of the nerve structure of P. falcata, as revealed by AChE histochemistry, with that of eight other species of triclad suggested that the nervous system of marine planarians is simpler than that of species of freshwater planarians, but revealed also that the nerve structure is rather variable among species.

The copulatory position exhibited by two partners in Paucumara falcata is remarkable in that they intertwine, with their heads pointing downwards and the tails pointing upwards, the entire process lasting about 10 min. Such a copulatory position has never before been reported for triclad flatworms.