Category Archives: worms

Friday Fellow: Scaly Lepidodermella

by Piter Kehoma Boll

From the longest animal seen last week, today we will see one of the shortest. Measuring only 190 µm in length, our fellow is called Lepidodermella squamata, which I turned into a “common” name as scaly lepidodermella.

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A specimen of Lepidodermella squamata. Photo by Giuseppe Vago.*

The scaly lepidodermella belongs to the phylum Gastrotricha, commonly known as hairybacks, which are all microscopic and distributed worldwide in aquatic environments. Found in freshwater environments worlwide, the scaly lepidodermella has the trunk covered in scales, hence its name. It feeds on other small organisms, such as algae, bacteria and yeast, as well as on detritus.

One of the most interesting aspects of the biology of the scaly lepidodermella is its reproduction. Although being hermaphrodite, this species usually produces only four eggs during its lifetime and those develop without fertilization. This means that the reproduction is parthenogenetic. However, strangely enough, the individuals become sexually mature after laying those four eggs, producing sperm and sometimes laying additional eggs, but most of those never hatch or, when they do, they produce offspring that rarely manage to become adults. Sexual reproduction, therefore, would be theoretically possible, but it has never been observed and there is no known means by which sperm could be transferred from one individual to the other.

This late sexual development may therefore be nothing but a vestige of its sexual past. Perhaps in future generations these traits will disappear and nothing but the perthenogenetic reproduction will last.

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References:

Hummon, M. R. (1984) Reproduction and sexual development in a freshwater gastrotrich 1. Oogenesis of parthenogenetic eggs (Gastrotricha). Zoomorphology 104(1): 33–41. https://dx.doi.org/10.1007/BF00312169

Hummon, M. R. (1986) Reproduction and sexual development in a freshwater gastrotrich 4. Life history traits and the possibility of sexual reproduction. Transactions of the American Microscopical Society 105(1): 97–109. https://dx.doi.org/10.2307/3226382

Wikipedia. Lepidodermella squamata. Available at <https://en.wikipedia.org/wiki/Lepidodermella_squamata&gt; Access on September 3, 2017.

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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.

lossless-page1-399px-nemertean_lineus_longissimus-tif

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.

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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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Darwin’s Planaria elegans: hidden, extinct or misidentified?

by Piter Kehoma Boll

During his epic voyage on the Beagle, Charles Darwin visited Rio de Janeiro, Brazil, and collected some amazing land planarians, a group that until then was very little known. One of the species he found was Geoplana vaginuloides, the type-species of the genus Geoplana, at that time named Planaria vaginuloides.

f6387-vaginuloides-pedrabranca40

Geoplana vaginuloides (Darwin, 1844), the first Brazilian land planarian species to be described. Photo by Fernando Carbayo.*

The second species described by Darwin was named Planaria elegans. Darwin’s description is as it follows:

“Position of the orifices as in P. vaginuloides. Anterior part of the body little elongated. Ocelli absent on the anterior extremity, and only a few round the margin of the foot. Colours beautiful; back snow-white, with two approximate lines of reddish brown; near the sides with several very fine parallel lines of the same tint; foot white, exteriorly clouded, together with the margin of the body, with pale blackish purple: body crossed by three colourless rings, in the two posterior of which the orifices are situated. Length 1 inch; breadth more uniform, and greater in proportion to length of the body, than in last species.
Hab. Same as in P. vaginuloides. [Rio de Janeiro]”

And this is all we know about this species. Darwin did not provide any drawing and later researchers did not report this species again, except when mentioning Darwin’s publication. As you can see by the description, it is not very accurate. He does not say what is the breadth of each line or band, neither how many of the “several fine parallel lines of the same tint” there are. Here is a quick drawing I did of how I imagine the creature would be:

image description

My idea of what Darwin’s Planaria elegans may have looked like. Head to the left. Credits to myself, Piter Kehoma Boll.**

In 1938, Albert Riester described a land planarian from Barreira, a district in the city of Teresópolis, Rio de Janeiro, naming it Geoplana barreirana. He described it as it follows (translated from the original in German):

“Land planarian found on a leaf after a rain; greatest lenght ca. 20 mm. Middle of the back white with two fine purple-red (atropurpureus light) parallel stripes. Outside of the white also limitted by pale red, then follows (on both sides) a black band and laterally a black-brown marmorate pattern over brown background. The middle stripe ends at the rear [end]. Head spotted, marked with transversal spotted bands (regenerate?). Underside gray, bordered by black-brown. Anterior end is arched backwards.”

Fortunately, Riester provided a drawing, which you can see below:

Barreirana_barreirana_Riester

Geoplana barreirana drawn by Riester (1938).

They look a bit alike, right? Fortunately Geoplana barreirana (currently named Barreirana barreirana) was found by later researchers and we have photographs! See one specimen below:

f6284_barreiranatijuca3

A specimen of Barreirana barreirana found in the Tijuca National Park, Rio de Janeiro. Photo by Fernando Carbayo.*

Riester did not describe any transversal marks on his specimens, but he may have mistaken them for color loss in preserved specimens or something like that. Otherwise the specimen looks very similar to Riester’s drawing, and the internal anatomy, which Riester provided as well, is also compatible.

Now let’s try to fit Darwin’s description of Planaria elegans in this photograph. White background, two reddish brown stripes and several fine parallel stripes of the same tint. He likely described the animals from preserved specimens, even though he have seen them alive and collected them. Perhaps the colors had already faded a little and the black stripes, which internally touch two of the reddish stripes, may have been considered a single purple-red stripe? It is not clear, in his description, whether there is white between the “reddish brown” stripes and the “pale blackish-purple” sides, as I did in my drawing, or not, as in Barreirana barreiranabut certainly the dark gray sides of B. barreirana could be the same as the pale blackish purple sides of Planaria elegans, don’t you think? And B. barreirana HAS three white “rings” crossing the body. You can see the first and the second very clearly on the specimen above. The third one is not very well marked, but you can see a third white mark interrupting the gray sides. And the second and almost third marks seem to be quite where one would expect the two orifices (mouth and gonopore) of the planarian to be!

And what about the ventral side? Darwin described P. elegan‘s as being white with a pale blackish purple border as the sides of the dorsum. Riester described G. barreirana‘s as being gray bordered by black-brown. Here is Barreirana barreirana‘s ventral side:

Barreirana barreirana from below

Ventral side of Barreirana barreirana from the Tijuca National Park, Rio de Janeiro. Photo by Fernando Carbayo.*

It is white, or pale gray perhaps, and the borders are of the same color as the sides of the dorsum!

I think it is very, very likely that Darwin’s Planaria elegans and Riester’s Geoplana barreirana are the same species. The fact that no one but Darwin has ever seen a specimen of Planaria elegans makes it even more likely.

What do you think?

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See also:

How are little flatworms colored? A Geoplana vaginuloides analysis.

The fabulous taxonomic adventure of the genus Geoplana.

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References:

Darwin, C. (1844) Brief Description of several Terrestrial Planariae, and of some remarkable Marine Species, with an Account of their Habits. Annals and Magazine of Natural History 14, 241–251.

Riester, A. (1938) Beiträge zur Geoplaniden-Fauna Brasiliens. Abhandlungen der senkenbergischen naturforschenden Gesellschaft 441, 1–88.

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Friday Fellow: Tiger Worm

by Piter Kehoma Boll

European in origin, but currently cosmopolitan, today’s Friday Fellow is a very useful earthworm for humans. Scientifically known as Eisenia fetida, this species has many different popular names, including tiger worm, red californian earthworm, red wiggler worm, etc.

Eisenia_fetida

Two specimens of Eisenia fetida. Photo by iNaturalist.org user nzwormdoctor.*

The tiger worm rarely lives underground, prefering to live among decaying vegetable matter, such as in the leaf litter, therefore being considered an epigean species. Due to its adaptability to live among and feed on decaying organic material, it is widely used by humans for vermicomposting, i.e., producing humus to be used as a nutrient rich soil in cultivation of vegetables. As a result, it has been introduced worlwide.

When molested, the tiger worm secrets a yellow and pungent liquid from its celomic cavity that has been shown to be toxic to some vertebrates, thus probably being a defense mechanism against predators.

Due to its agriculatural importance, the tiger worms has been used in many studies regarding its response to different soil contaminants, including pesticides, and its presence on the amount of inorganic nutrients, such as carbon and nitrogen, in the soil.

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References:

Albanell, E.; Plaixats, J.; Cabrero, T. (1988) Chemical changes during vermicomposting (Eisenia fetida) of sheep manure mixed with cotton industrial wastes. Biology and Fertility of Soils, 6(3): 266–269.

Spurgeon, D. J.; Hopkin, S. P. (1999) Comparisons of metal accumulation and excretion kinetics in earthworms (Eisenia fetida) exposed to contaminated field and laboratory soils. Applied Soil Ecology, 11(2–3): 227–243.

Zhang, B.-G.; Li, G.-T.; Shen, T.-S.; Wang, J.-K.; Sun, Z. (2000) Changes in microbial biomass C, N, and P and enzyme activities in soil incubated with the earthworms Metaphire guillelmi or Eisenia fetidaSoil Biology and Biochemistry, 32(14): 2055–2062.

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Friday Fellow: Brown-gutted Mud Roundworm

by Piter Kehoma Boll

If you have your face buried in the mud at the bottom of a European lake, you may end up finding some of those tiny little roundworms known as Monhystera stagnalis. As usual, there is no common name for this species, but I decided to call it brown-gutted mud roundworm. Why? Because it lives in the mud and has a reddish-brown gut.

monhystera_stagnalis

An individual of Monhystera stagnalis. Photo by Marco Spiller.*

The brown-gutted mud roundworm is a widely distributed roundworm species, being common especially throughout Europe. It inhabits the fine sediments at the bottom of freshwater bodies, both stagnant and flowing, where it feeds on the organic material deposit in this medium, having a special taste for bacteria. It is able to survive in moderate organic pollution, but is sensitive to low oxygen levels.

It is one of the most common nematode species in its environment and it is very small, measuring around 1 mm in length, females being slightly longer than males. They are found in all depths of the sediment and seem to have a preference for staying closer to the surface during winter and deeper in the mud during summer.

Females are ovoviviparous, meaning that they retain the egg inside their bodies until they hatch, so they are pregnant with eggs. Although we are used to think that invertebrates produce hundreds or thousands of eggs at once, this is not the case with the brown-gutted mud roundworm. Females are usually pregnant of a single egg, sometimes with two or three. They are modest worms.

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ResearchBlogging.orgReferences:

Pehofer, H. (1989). Spatial Distribution of the Nematode Fauna and Production of Three Nematodes (Tobrilus gracilis, Monhystera stagnalis, Ethmolaimus pratensis) in the Profundal of Piburger See (Austria, 913 m a.s.l) Internationale Revue der gesamten Hydrobiologie und Hydrographie, 74 (2), 135-168 DOI: 10.1002/iroh.19890740203

Traunspurger, W. (1996). Autecology of Monhystera paludicola De Man, 1880 – Seasonal, Bathymetric and Vertical Distribution of a Free-living Nematode in an Oligotrophic Lake Internationale Revue der gesamten Hydrobiologie und Hydrographie, 81 (2), 199-211 DOI: 10.1002/iroh.19960810205

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Friday Fellow: Persian Carpet Flatworm

ResearchBlogging.orgby Piter Kehoma Boll

A flatworm again, at last! Not a land planarian, but a flatworm nonetheless.

If there is a group of flatworms that may put land planarians in second plan regarding beauty, those are the polyclads. Living in the sea, especially in coral reefs, polyclads are colorful and curly and may be mistaken by sea slugs.

The species I’m introducing here today is Pseudobiceros bedfordi, commonly known as the Persian carpet flatworm or Bedford’s flatworm. It is about 8 cm long and lives in coral reefs along Australia, Indonesia, Philippines and adjacent areas. See how beautiful it is:

A flatworm (Pseudobiceros bedfordi). Raging Horn, Osprey Reef, Coral Sea

The Persian carpet flatworm with its beautiful colors. Photo by Richard Ling.*

The colorful pattern of this and many other polyclad species is likely a warning about their toxicity, although there are few studies regarding toxicity in these animals. Being active predators, polyclads may use their toxins as a way to subdue prey as well.

But the most interesting thing regarding the Persian carpet flatworm is its sexual behavior. As with most flatworms, they are hermaphrodites, so when two individuals meet and decide to have sex, they have to choose whether they want to play the male or the female role (or both). Unfortunately, most individuals prefer to be males, so those encounters usually end up in a violent fight in which both animals attack the partner with a double penis, a behavior known as penis fencing.

mating_pseudobiceros_bedfordi

Two Persian carpet flatworms about to engage in penis fencing. Photo from Whitfield (2004), courtesy of Nico Michiels.**

At the end, the winner spurts its sperm onto the partner and leaves. The horrible part is yet to come, though. The sperm appears to be able to burn like acid through the receiver’s skin tissue in order to reach the inner tissues and thus swim towards the eggs. In some extreme cases the sperm load may be high enough to tore the receiver into pieces! If that’s not a good definition of wild sex, I don’t know what is.

See also: Gender Conflict: Who’s the man in the relationship?

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References:

Whitfield, J. (2004). Everything You Always Wanted to Know about Sexes PLoS Biology, 2 (6) DOI: 10.1371/journal.pbio.0020183

Wikipedia. Pseudoceros bedfordi. Available at: <https://en.wikipedia.org/wiki/Pseudobiceros_bedfordi&gt;. Access on November 24, 2016.

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Obama invades Europe: “Yes, we can!”

ResearchBlogging.orgby Piter Kehoma Boll

This information was known by me and some other people for quite a while, but only recently has caught attention of the general public. Obama is the newest threat in Europe.

No, I’m not talking about the president of the United States. I’m talking about a land flatworm whose name is  Obama nungara.

obama_marmorata_7

This is the magnificent Obama nungara. This specimen is from Brazil and looks particulary yellowish due to the strong light of the camera flash. Photo by Piter Kehoma Boll.*

It has been a while since a new invasive land flatworm started to appear in gardens of Europe, especially in Spain and France and eventually elsewhere, such as in the United Kingdom. It was quickly identified as being a Neotropical land planarian and posteriorly as belonging to the genus Obama, whose name has nothing to do with Barack Obama, but is rather a combination of the Tupi words oba (leaf) and ma (animal) as a reference to the worm’s shape.

obama_nungara

When you find Obama nungara in your garden, it will look much darker, like this one found in the UK. Photo by buglife.org.uk

At first it was thought that the planarian belonged to the species Obama marmorata, a species that is native from southern Brazil, but molecular and morphological analyses revealed it to be a new species. Actually, much of what was called Obama marmorata in Brazil was this new species. Thus, it was named nungara, which means “similar” in Tupi, due to its similarity with Obama marmorata.

obama_marmorata

This is Obama marmorata, the species that O. nungara was originally mistaken for. Photo by Fernando Carbayo.**

Measuring about 5 cm in length, sometimes a little more or a little less, O. nungara is currently known to feed on earthworms, snails, slugs and even other land planarians. Its impact on the European fauna is, however, still unknown, but the British charitable organization Buglife decided to spread an alert and many news websites seem to have loved the flatworm’s name and suddenly a flatworm is becoming famous.

Who said flatworms cannot be under the spotlight? Yes, they can!

See also: The Ladislau’s flatworm, a cousin of Obama nungara.

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References:

Álvarez-Presas, M., Mateos, E., Tudó, À., Jones, H., & Riutort, M. (2014). Diversity of introduced terrestrial flatworms in the Iberian Peninsula: a cautionary tale PeerJ, 2 DOI: 10.7717/peerj.430

Boll, P., & Leal-Zanchet, A. (2016). Preference for different prey allows the coexistence of several land planarians in areas of the Atlantic Forest Zoology, 119 (3), 162-168 DOI: 10.1016/j.zool.2016.04.002

Carbayo, F., Álvarez-Presas, M., Jones, H., & Riutort, M. (2016). The true identity of Obama (Platyhelminthes: Geoplanidae) flatworm spreading across Europe Zoological Journal of the Linnean Society, 177 (1), 5-28 DOI: 10.1111/zoj.12358

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