The Cow Tongue’s taste revealed! Giant planarian found eating giant snail!

by Piter Kehoma Boll

Polycladus gayi is an iconic land planarian found in Chile and locally known as lengua de vaca (cow tongue). Despite being the largest land planarian in Chile and one of the first land planarians to be described, back in 1845, we know almost nothing about its ecology.

However, things are changing! In the past months, two specimens have been found eating in the wild, and, in both cases, the prey was the same species, the giant black snail, Macrocyclis peruvianus, the largest snail in Chile. Both observations occurred in Chilean protected areas, Villarrica National Park and Alerce Costero National Park, and were recorded by nonspecialists visiting the areas. One more important discovery that happened thanks to citizen science!

The land planarian Polycladus gayi attached to snail Macrocyclis peruvianus and feasting on its flesh. Photo by Yerko Lloncón.*

After almost two centuries since P. gayi was discovered, we finally know something about its place in the food chain! And, of course, it also helps us see M. peruvianus from a new perspective since this also seems to be the first record of one of its predators! Even though snails are a common item in the diet of land planarians, not all species feed on them, and we cannot assume that both groups are always directly connected in the food web.

Come see how chubby the planarian got after eating the whole snail!

There is still much more to discover about these two unique Chilean creatures, and the partnership between researchers and the general public is an important way to speed up the process of gathering knowledge about the creatures around us!

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Reference:

Boll PK, Lloncón Y, Almendras D (2023) Records of the land planarian Polycladus gayi (Tricladida, Geoplanidae) preying on black snails Macrocyclis peruvianus (Gastropoda, Macrocyclidae). Austral Ecology. https://doi.org/10.1111/aec.13430

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* This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

Friday Fellow: Colorful Sidegill Slug

by Piter Kehoma Boll

[leia em português]

Some species are so peculiar and cute that they look like real-life Pokémon (well, at least what Pokémon used to look like back in the first generations). One of those species is Berthella martensi, the colorful sidegill slug.

A white specimen with dark spots in Australia. Photo by Steve Smith.*

Inhabiting the Indo-Pacific, from the intertidal zone up to a depth of about 25 m, the colorful sidegill slug measures about 5 to 6 cm in length as an adult and is often found in shallow lagoons in coral reefs. It is a pleurobranch, a group of sea slugs with an external gill located on the right side of the body, in contrast to the more famous nudibranchs, which have it on the back.

One of the most typical color patterns of the colorful sidegill slug. Photo by Karen (iNaturalist’s user kswt).*

The colorful sidegill slug has a prominent mantle that extends in the form of large lobes covering its body, including its gill. These lobes can be autotomized when the animal feels threatened so that it can escape and leave the predator behind with a small snack to get distracted. But the colorful sidegill slug is a predator itself, feeding on sponges and, according to some sources, also ascidians.

A specimen with all of its mantle lobes autotomized. The foot is clearly visible, and so is the gill on the right side (zoom in the detail at the lower left corner). Credits to W. B. Rudman. Extracted from http://www.seaslugforum.net/factsheet/defauto.

A specimen feeding on a sponge in Palawan, Philippines. Photo by Alain Bonnet. Extracted from http://www.seaslugforum.net/find/17244

But certainly one of the most remarkable features of the colorful sidegill slug is the variety of different color patterns that the species can present. It can be light cream, almost white, or dark purple, almost black, with many colors in between, such as yellow, orange, red, or purple-gray. Besides the background color, there are often several spots that are of a lighter color in dark-colored animals and of a darker color in light-colored ones. Specimens with a light background color can also have a dark margin on the mantle lobes, usually with the same color as the spots, although this is not always present. In dark-colored ones, the margin has always the same color as the background.

A dark-colored individual from Papua-New Guinea. Photo by Erik Schlogl.*

Despite its beauty and cuteness, the colorful sidegill slug is one more species whose ecology is almost completely unknown to us. Even though it has a charismatic look, no one cared to get to know it better until now.

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References:

Rudman, W.B., 1998 (October 28) Berthella martensi (Pilsbry, 1896). [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/bertmart

Yonow, N. (2015). Sea Slugs: unexpected biodiversity and distribution. In The Red Sea (pp. 531-550). Springer, Berlin, Heidelberg. https://link.springer.com/chapter/10.1007/978-3-662-45201-1_30

Wikipedia. Berthella martensi. Available from https://en.wikipedia.org/wiki/Berthella_martensi. Access on 1 December 2022.

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* This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

Friday Fellow: Elegant Hawkmoth

by Piter Kehoma Boll

Lepidopterans are among the most beloved invertebrates among the general public, especially because of the beauty of either the adult or the larval forms, or sometimes even the pupa! Hawkmoths are among those groups that often call people’s attention. They make up the family Sphingidae, and the adults have a peculiar and easily recognizable shape, but their caterpillars are most remarkable.

An adult of the elegant hawkmoth in Indonesia. Photo by Franz Anthony.*

The Elegant Hawkmoth, Eupanacra elegantulus, is a species found in Southeast Asia. The adults have a brownish color that is not that different from an average hawkmoth. The caterpillars, on the other hand, are very interesting. They feed on plants of the family Araceae, including the genera Aglaonema, Alocasia, Dieffenbachia, Monstera and Syngonium, many of which are highly toxic.

A very young caterpillar with its somewhat plain green color and straight spine near the posterior end. Photo by Ananda Virgiana.*

They live on the underside of the leaves on which they feed and start their lives as small, almost plain green caterpillars, with a small straight spine near the posterior end. At their last instars, they show a curious pattern. The spine at the posterior end becomes hooked, and a little behind the three pairs of true legs the dorsum shows a large eyespot on each side. A black line forming a more or less oval shape connects the eyespots on both sides, and the area that this line surrounds shows a pattern that resembles reptile scales.

A brown caterpillar with the head withdrawn, making it look like a snake. Photo by iNaturalist user klearad.*

The body at this stage can be either green or brown, and the caterpillar kind of resembles a snake, when its head is withdrawn, or a crocodile, when it is extended forward.

A caterpillar with the head exposed, making it look kind of like a crocodile. Photo by iNaturalist user tchaianunporn.*

When they pupate, they attach themselves under a leaf surrounded by a very loose cocoon of silk with some debris.

A pupa surrounded by the very loose cocoon of silk and debris. Photo by Ananda Virgiana.*

Despite being a species with a very interesting pattern that mimics snakes or crocodiles, which catches the attention of many people, there are no studies at all focused on this species. Nowadays, citizen science is becoming an important source of knowledge and I think this species would benefit a lot of projects that include the participation of the community.

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References:

Samuel. Eupanacra elegantulus life history. Common butterflies of Singapore. Available at < http://butterybuttermoth.blogspot.com/2009/03/eupanacra-elegantulus-life-history.html >. Access on 16 November 2022.

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* This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

Friday Fellow: Shore-dwelling Swordworm

by Piter Kehoma Boll

One of the most enigmatic animal phyla is Chaetognatha, which are commonly known as arrow worms. Less than 200 species are known, but some species are very abundant, so it is not that difficult to find one if you look at the right place. One particularly common species is Spadella cephaloptera, which I decided to call the shore-dwelling swordworm.

A typical shore-dwelling swordworm. Head to the right, Photo by Wikimedia user Zatelmar.**

All arrowworms are very small, measuring up to 10 or 12 cm in the largest specimens, but the shore-dwelling swordworm is much smaller, with only about 5 mm in length. They are marine creatures and most species are planktonic, but the shore-dwelling swordworm is an exception that lives in shallow waters near the shore, usually attached to the surface of seaweed or marine angiosperms around Europe.

Detail of the head showing the grasping spines at the sizes and the two small black eyes. Photo by Lukas Schärer.*

The body of the shore-dwelling swordworm is kind of dart-shaped, transparent, and consists of a rounded head, an elongate trunk and a short tail. The second half of the trunk and the tail are surrounded by a flat expansion that functions like a fin. Like in all arrowworms, the shore-dwelling swordworm has one set of hooked, grasping spines on each side of the head, on their “cheeks”. They use these spines to capture their prey, which consist mainly of small crustaceans living in the same habitat.

The shore-dwelling swordworm is a hermaphrodite like all arrowworms. The female reproductive apparatus lies in the second half of the trunk and the male one in the tail. Mating does not include reciprocal insemination like in other hermaphrodites. One of the two individuals, which has its seminal vesicles full, approaches another, which has its seminal receptacle empty, and deposits a mass of sperm at the entrance of the vagina of the second. The cilia of the vagina start to become very active and the spermatozoa start to swim across the cilia to enter the vagina until they reach the seminal receptacle.

Detail showing the seminal vesicles as two brown structures on each side. Photo by Lukas Schärer.*

Both individuals remain in contact, with one facing the tail of the other, until the seminal receptacle of the receiving one is full or until they are disturbed. If some sperm mass still remains outside of the vagina when they separate, the receiving one eats what has been left out. After the eggs are fertilized, they still remain some hours inside the mother until they are laid. About 12 to 16 eggs are laid at intervals of eight to ten days. The eggs remain attached to the substrate and, in about 48 hours, they hatch into small versions of the adults, without a larval phase.

Detail showing several eggs at different stages of development on each side of the body. Photo by Lukas Schärer.*

Although almost invisible and often ignored, the shore-dwelling swordworm is an important predator in this specific shore ecosystem which is, of course, connected to the large marine ecosystem and, consequently, to the whole biosphere. But how much do they affect the dynamics of their ecosystem? This is something that still needs to be investigated.

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References:

Goto, T. (1999). Fertilization process in the arrow worm Spadella cephaloptera (Chaetognatha). Zoological science, 16(1), 109-114. https://doi.org/10.2108/zsj.16.109

John, C. C. (1933). Habits, Structure, and Development of Spadella cephaloptera. Journal of Cell Science, 2(300), 625-696. https://doi.org/10.1242/jcs.s2-75.300.625

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* This work is licensed under a Creative Commons Attribution 4.0 International License.

** This work is licensed under a Creative Commons Attribution 3.0 Unported License.

Friday Fellow: Mediterranean Plumefoot Mite

by Piter Kehoma Boll

There are endless forms of beauty among the small creatures that we often do not see around us. Mites, which are so ubiquitous, contain several neglected beauties. One of them is today’s fellow, Eatoniana plumipes, known as the Mediterranean Plumefoot Mite.

Mediterranean Plumefoot Mite photographed in Spain by Simon Oliver*.

Adults of the Mediterranean Plumefoot Mite are considerably large for a mite, measuring a few millimeters in length, often more than 1 cm when the legs are considered. They are reddish-brown, lighter at the legs and other appendices, and their hind legs are much longer than the others and have a tuft of long black hair that makes them look like plumes, hence the name plumefoot mite. As the common name also suggest, this species is found around the Mediterranean, including southern Europe, northern Africa, Turkey and the Middle East.

Despite being a large and rather beautiful mite, very little is known about the life history of the Mediterranean Plumefoot Mite. It belongs to a group of mites that are predators as adults but parasites as larvae. The larvae hatch from red eggs laid by the female in the environment and are, of course, much smaller than the adults. They also have only three pairs of legs, and not four like the adults, and lack the characteristic plumes seen in the adults.

Some eggs of the Mediterranean Plumefoot Mite and one recently hatched larva. Extracted from Mąkol & Sevsay (2015).

Little to nothing is known about the feeding habits of this species. Grasshoppers are among the identified hosts of the larvae, but it is likely that other arthropods are parasitized as well. The larvae attach to the legs of the hosts and feed there, sucking their hemolymph (the “blood” of arthropods). I could not find any information about which species serve as prey for the adults.

Even though we know almost nothing about the ecology of the Mediterranean plumefoot mite, we can still appreciate its beauty, and it certainly plays a fundamental role in its ecosystem.

If you live around the Mediterranean, have you ever seen one of them? Let us know!

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More mites:

Friday Fellow: Giant red velvet mite (on 22 July 2016)

Friday Fellow: Cuban-laurel-thrips mite (on 28 June 2019)

Friday Fellow: Rhinoceros Tick (on 18 October 2019)

Friday Fellow: Aloe Mite (on 7 February 2020)

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References:

GBIF. Eatoniana plumipes (L. Koch, 1856). Available at < https://www.gbif.org/species/4539982 >. Access on 20 October 2022.

Mąkol, J., & Sevsay, S. (2015). Abalakeus Southcott, 1994 is a junior synonym of “plume-footed” Eatoniana Cambridge, 1898 (Trombidiformes, Erythraeidae)-evidence from experimental rearing. Zootaxa, 3918(1), 92-112. https://doi.org/10.11646/zootaxa.3918.1.4

Noei, J., & Rabieh, M. M. (2019). New data on Nothrotrombidium, Southcottella and Eatoniana larvae (Acari: Trombellidae, Neothrombiidae, Erythraeidae) from Iran. Persian Journal of Acarology, 8(3). https://doi.org/10.22073/pja.v8i3.46776

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* This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

Friday Fellow: Bristly Millipede

by Piter Kehoma Boll

Millipedes make up a beautifully diverse group of arthropods. They do not only include the typical cylindrical critters with many legs that curl up into a spiral, but also astonishing long ones with more legs than you could imagine, some with the amazing ability to glow in the dark, and then there’s today’s species, Polyxenus lagurus, the bristly millipede.

You have to be very attentive to notice the bristly millipede, as it measures only 3 to 4 mm in length as an adult. And even if you do notice it, you may not think at first that it is a millipede. I mean, look at it at the image below. It is very short and fluffy, with its body all covered by small hair-like projections, or bristles, hence the name.

Would you think this is a millipede if you did not know this is a millipede? Photo by Andy Murray.**

The bristly millipede is found in Europe and North America and belongs to a very divergent group of millipedes, the Polyxenida. The exoskeleton of polyxenid millipedes is soft, not calcified as in most millipede species. Even so, they are very resistant to drought and occur often in dry places, such as among rocks or in the leaf litter of xeric (very dry) regions. The food of the bristly millipede consists mainly of lichens and algae, which it consumes mostly while they are dehydrated so that they provide little to no water.

How can this small bug survive in a dry environment eating dried-out food? Where does it get its water from? From the air, of course! A study found out that the bristly millipede can absorb water vapor directly from the air.

Just look at how amazing this creature is in all its details. Foto by Gilles San Martin.**

Despite its very small size, the bristly millipede can defend itself quite well, at least against arthropod predators, such as ants and spiders. When feeling threatened, the bristly millipede strokes the predators with its bristly “tail”. This makes several spines that form the tail be released on the surface of the predator’s body. These spines have recurved tips that hook onto the hairs on the surface of the predators and, as the predators try to groom themselves to get rid of the spines, they only get more and more entangled, as the spines start to hook onto each other. The predator becomes so entangled that it cannot move anymore and ends up dying slowly of starvation or dehydration.

The bristly millipede is a real fluffy badass.

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References:

Eisner, T., Eisner, M., & Deyrup, M. (1996). Millipede defense: use of detachable bristles to entangle ants. Proceedings of the National Academy of Sciences, 93(20), 10848-10851. https://doi.org/10.1073/pnas.93.20.10848

Wright, J. C., & Westh, P. (2006). Water vapour absorption in the penicillate millipede Polyxenus lagurus (Diplopoda: Penicillata: Polyxenida): microcalorimetric analysis of uptake kinetics. Journal of experimental biology, 209(13), 2486-2494. https://doi.org/10.1242/jeb.02280

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** This work is licensed under a Creative Commons Attribution-Share Alike 2.0 Generic License.

The secret sex life of the bloody ribbon worm

by Piter Kehoma Boll

Ribbon worms (phylum Nemertea) are an interesting but understudied animal phylum. It includes many marine species, such as the bootlace worm, Lineus longissimus, the longest known animal. One of its close relatives is the bloody ribbon worm, Lineus sanguineus, which is much shorter but found in oceans worldwide.

A bloody ribbon worm in New Zealand. Photo by Amaya M.*

A peculiar aspect of the bloody ribbon worm is the fact that no one has ever seen them having sex, I mean, reproducing sexually. Marine ribbon worms just throw their gametes in the water and do not have sexual intercourse per se. Anyway, while most ribbon worms, including other species of the genus Lineus, have sexual reproduction as their main reproductive strategy, the same is not true for Lineus sanguineus, or is it? After decades of observations, no one has ever seen this species reproducing sexually, even though males and females have been seen producing sperm and eggs. However, females produce very few eggs compared to other species and seem to “abort” them. The main mode of reproduction of this species is by fragmentation and later regeneration of the missing parts, similar to how many planarians do. This is, in fact, very rare among ribbon worms.

But do they really live without sexual reproduction? A recent study by Christina Sagorny and Jörn von Döhren challenged this idea. They compared the sequences of three genes from individuals from different populations around the world. If asexual reproduction were the only form of reproduction, the expected pattern would be of little genetic variation within populations and more genetic variation between populations. The results of the haplotype networks, however, show otherwise. There is a huge genetic variation within populations and little variation between populations, which suggests not only that sexual reproduction occurs but that the species constantly spreads around the world, possibly via the planktonic larvae.

Haplotype networks of the bloody ribbon worm. If asexual reproduction was the only form of reproduction, one would expect fewer haplotypes per region and few shared haplotypes between regions, so that the circles would have only one or a few colors. Extracted from Sagorny & von Döhren (2022).

By raising some worms in the lab under summer conditions (18° C and 16 h of light) and others under winter conditions (9° C and 8 h of light), they found that most worms become sexually mature during winter and, surprisingly, reproduce by fission more often in winter too. More than that, they even found some larvae in the water, indicating that sexual reproduction occurred successfully.

What can we conclude? The bloody ribbon worm does have sex. It just likes to make it in private.

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Reference:

Sagorny, C., & von Döhren, J. (2022). Occasional sexual reproduction significantly affects the population structure of the widespread, predominantly asexually reproducing marine worm Lineus sanguineus (Nemertea: Pilidiophora). Marine Biology, 169(7), 1-17. https://doi.org/10.1007/s00227-022-04077-0

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* This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

Friday Fellow: Brazilian Diamond Weevil

by Piter Kehoma Boll

Weevils are the largest family of beetles, which are the largest order of insects, which are the largest class of arthropods and so on… Thus, it is time to bring one more weevil here. I decided to talk about a beautiful and considerably popular Brazilian species, Entimus imperialis, which is known as the Brazilian Diamond Weevil.

Occurring in the Atlantic Forest in southeastern Brazil, this is a relatively large weevil, measuring up to 3 cm in length. The body has a black background, but it is covered by several rows of pits that are filled with iridescent scales that create an effect of golden green dots due to the presence of photonic crystals. Additionally, there are some iridescent green-blue areas on the legs and forming stripes on the dorsum.

A magnificent specimen from Atibaia, São Paulo. Foto by Whaldener Endo.**

As the scales are arranged inside concave pits, the weevil’s appearance changes drastically depending on the distance from the observer. When seen from far away, it merges perfectly with the green background of the leaves, which is useful to make it invisible to predators. However, when seen from a short distance, the dotted iridescent pattern becomes quite conspicuous and this is thought to be important for the Brazilian Diamond Weevil to recognize others of the same species.

A specimen in Angra dos Reis, Rio de Janeiro. Photo by Edvandro Abreu Ribeiro.*

Despite the extensive study of the optical and structural properties of the scales of the Brazilian Diamond Weevil, little, or perhaps nothing, seems to be known about its ecology. Larvae of other closely related weevil species feed on plants roots while adults feed on the leaves of the same plant, but I was unable to find any information about which plants are used by the Brazilian Diamond Weevil as food.

A specimen from Piranga, Minas Gerais, on a human hand for size comparison. Photo by William R S Maciel.*

According to the records in iNaturalist, adults seem to be found between November and July, especially from November to May. Thus, they most likely die by the end of the autumn and pass the winter as eggs or perhaps larvae.

And that’s all I can tell about this beautiful but little know creature.

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References:

iNaturalist. Brazilian Diamond Weevil (Entimus imperialism). Available at: < https://www.inaturalist.org/taxa/631444-Entimus-imperialis >. Access on 14 July 2022.

Morrone, J. J. (2002). The Neotropical weevil genus Entimus (Coleoptera: Curculionidae: Entiminae): Cladistics, biogeography, and modes of speciation. The Coleopterists Bulletin, 56(4), 501-513. https://doi.org/10.1649/0010-065X(2002)056[0501:TNWGEC]2.0.CO;2

Mouchet, S., Colomer, J. F., Vandenbem, C., Deparis, O., & Vigneron, J. P. (2013). Method for modeling additive color effect in photonic polycrystals with form anisotropic elements: the case of Entimus imperialis weevil. Optics Express, 21(11), 13228-13240. https://doi.org/10.1364/OE.21.013228

Wilts, B. D., Michielsen, K., Kuipers, J., De Raedt, H., & Stavenga, D. G. (2012). Brilliant camouflage: photonic crystals in the diamond weevil, Entimus imperialis. Proceedings of the Royal Society B: Biological Sciences, 279(1738), 2524-2530. https://doi.org/10.1098/rspb.2011.2651

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* This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

** This work is licensed under a Creative Commons Attribution 4.0 International License.

Friday Fellow: Japanese Pauropod

by Piter Kehoma Boll

We reached one more moment in which things get a little disheartening because it is time to talk about another group of neglected organisms, the pauropods. These very small arthropods measure only a few milimeters in length and belong to the subphylum Myriapoda, being related to the most popular centipedes and milipedes.

I was unable to have easy access to good information of any species, so I decided to talk about the only one of which I found a good photograph and that was determined to the species level, Eurypauropus japonicus, which I decided to call the Japanese pauropod.

The Japanese pauropod measures less than 2 mm in length, usually between 1.5 and 1.7 mm. The adults have a pair of antennae and nine pairs of legs, one in each segment behind the head, except for the last (one, or two?) segment. The dorsal side is covered by five heavily sclerotized plates, which gives the impression that they have fewer segments.

The only photo of a pauropod determined to the species level, Eurypauropus japonicus, that I could find. Thanks to Ryosuke Kuwahara.*

Like all pauropods, the Japanese pauropod avoids light, living in dark humid places in the forest soil, often inside and below rotten wood. Pauropods in general are not found in large densities, and I think the same applies to the Japanese pauropod. Its diet is unknow, but it most likely feeds on fungi and, perhaps, live or decaying plant matter as well.

Details about its reproduction are unknown as well. Based on information of other pauropods, mating probably occurs with the males depositing a spermatophore (a sperm-filled sac) on the substrate, which is then collected by the female to fertilize her eggs. Newly hatched pauropods have only three pairs of legs, but this number increased at every mold until reaching, in the Japanese pauropod, the maximum of nine pairs.

The pauropods are one more group of organisms that, because of their lack of cuteness and “beauty”, do not attract the attention of the general public, and this is also reflected in the lack of interest in studying them by biologists in general. How can we change that?

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References:

HAGINO, Y., & SCHELLER, U. (1985). A new species of the genus Eurypauropus (Pauropoda: Eurypauropodidae) from central Japan. Proceedings of the Japanese Society of Systematic Zoology (Vol. 31, pp. 38-43). The Japanese Society of Systematic Zoology.

Wikipedia. Pauropoda. Available at < https://en.wikipedia.org/wiki/Pauropoda >. Access on 14 October 2021.

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* This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

Friday Fellow: Bootlace Worm

by Piter Kehoma Boll

Long ago I presented some of the extremes of the animal world, including the largest, the cutest and the leggiest. Now it’s time to introduce another extreme: the longest. And this animal is so long that it seems impossible. Its name: Lineus longissimus, commonly known as bootlace worm. Its length: up to 55 meters.

An entangled bootlace worm. Photo by Bruno C. Vellutini.*

The bootlace worm is a member of the phylum Nemertea, commonly known as ribbon worms, and is found along the shores of the Atlantic Ocean in Europe. Most of the time, the worm is contracted, forming what looks like a heap of entagled wool threads that has no more than 30 cm from side to side. Although there are reports of specimens measuring more than 50 m, most of them are much shorter, with 30 m being already a very large size. Its width is of about 0.5 cm, so it is almost literally a long brown thread.

Lineus longissimus photographed in Norway. Photo by Guido Schmitz.**

As all nemerteans, the bootlace worm is a predator and hunts its prey between the rocks on sandy shores, stunning them with its long poisonous proboscis and then swallowing them whole. Soft and fragile, the bootlace worm has no way to protect itself from predators using any physical defense, but it is known to have a series of different toxins on its epidermis, including some similar to the deadly pufferfish poison tetrodotoxin (TTX) that is produced by bacteria living in the mucus that surrounds the body of the worm.

Now, before leaving, take a look at this video of a bootlace worm swallowing a polychaete:

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References:

Cantell, C.-E. (1976) Complementary description of the morphology of Lineus longissimus (Gunnerus, 1770) with some remarks on the cutis layer in heteronemertines. Zoologica Scripta 5:117–120. https://dx.doi.org/10.1111/j.1463-6409.1976.tb00688.x

Carroll, S.; McEvoy, E. G.; Gibson, R. (2003) The production of tetrodotoxin-like substances by nemertean worms in conjunction with bacteria. Journal of Experimental Marine Biology and Ecology 288: 51–63. https://dx.doi.org/10.1016/S0022-0981(02)00595-6

Gittenberger, A.; Schipper, C. (2008) Long live Linnaeus, Lineus longissimus (Gunnerus, 1770) (Vermes: Nemertea: Anopla: Heteronemertea: Lineidae), the longest animal worldwide and its relatives occurring in The Netherlands. Zoologische Mededelingen. Leiden 82: 59–63.

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*
This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.

**
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.