Tag Archives: land planarians

Land snails on islands: fascinating diversity, worrying vulnerability

by Piter Kehoma Boll

The class Gastropoda, which includes snails and slugs, is only beaten by the insects in number of species worldwide, having currently about 80 thousand described species. Among those, about 24 thousand live on land, where they are a very successful group, especially on oceanic islands.

The Hawaiian Islands alone, for example, have more than 750 snail species and there are more than 100 endemic species in the small island of Rapa in the South Pacific. This diversity is much higher than that in any continental place, but the reason for that is not completely understood.

Mandarina

A land snail of the genus Mandarina, endemic to the Ogasawara Islands, Japan. Photo by flickr user kmkmks (Kumiko).*

One of the most likely explanations for this huge diversity on islands is related to the lack of predators. The most common predators of snails include birds, mammals, snakes, beetles, flatworms and other snails. Most of those are not present in small and isolated islands, which allows an increase in land snail populations in such places. Without too much dangers to worry about, the community of land snails n islands can explore a greater range of niches, eventually leading to speciation.

Unfortunately, as always, the lack of danger leads to recklessness. Without predators to worry about, insular land snails tend to lay fewer eggs than their mainland relatives. If there is no danger of having most of your children eaten, why would you have that many? It is better to lay larger eggs, putting more resources on fewer babies, and so assure that they will be strong enough to fight against other snail species. Afterall, the large number of species in such a small place as an island likely leads to an increased amount of competition between species.

But why is this recklessness? Well, because you never known when a predator will arrive. And they already arrived… due to our fault.

The diversity of insular land nails was certainly affected by habitat loss promoted by humans, but also by predators that we carried with us to the islands, whether intentionally or not. These predators include rats, the predatory snail Euglandina rosea and the land flatworm Platydemus manokwari, the latter being most likely the worst of all.

800px-platydemus_manokwari

The flatworm Platydemus manokwari in the Ogasawara Islands. Photo by Shinji Sugiura.

This flatworm arrived at the Chichijima Island, part of the Ogasawara Islands in the Pacific Ocean, in the early 1990s and in about two decades it led most land snail species on the island to extinction and many more are about to face the same fate on this island and on others. Not being prepared for predators, these poor snails cannot reproduce fast enough to replace all individuals eaten by the flatworm.

We have to act quickly if we want to save those that are still left.

See also: The New Guinea flatworm visits France – a menace.

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ResearchBlogging.orgReferences and further reading:

Chiba, S., & Cowie, R. (2016). Evolution and Extinction of Land Snails on Oceanic Islands. Annual Review of Ecology, Evolution, and Systematics, 47 (1), 123-141 DOI: 10.1146/annurev-ecolsys-112414-054331

Sugiura, S., Okochi, I., & Tamada, H. (2006). High Predation Pressure by an Introduced Flatworm on Land Snails on the Oceanic Ogasawara Islands. Biotropica, 38 (5), 700-703 DOI: 10.1111/j.1744-7429.2006.00196.x

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New Species: July 11 to July 20

by Piter Kehoma Boll

Here is a list of species described from July 11 to July 20. It certainly does not include all described species. Most information comes from the journals Mycokeys, Phytokeys, Zookeys, Phytotaxa, Zootaxa, International Journal of Systematic and Evolutionary Microbiology, and Systematic and Applied Microbiology, as well as journals restricted to certain taxa.

Pseudoechthistatus sinicus(top) and P. pufujiae are two of the more than 40 new species of beetles described in the last 10 days.

Pseudoechthistatus sinicus (top) and P. pufujiae (bottom) are two of the 40 new species of beetles described in the last 10 days.

Archaea

Bacteria

SARs

Plants

Excavates

Fungi

Sponges

Flatworms

Annelids

Mollusks

Roundworms

Arachnids

Myriapods

Crustaceans

Hexapods

Cartilaginous fishes

Ray-finned fishes

Reptiles

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Flickr, a paradise of photographs of unknown species

by Piter Kehoma Boll

Currently there are about 1,2 million species described worldwide and hundreds of new species are found and described every month. Some estimations predict that Earth currently contains more than 10 million species, meaning that we still know very little of our diversity. The hundreds of species described monthly may look as a huge progress, but actually we are running in a very slow pace, mainly due to the lack of taxonomists, but also because of the few resources devoted to research in biodiversity.

Most people may think that in the current world, a new species represents some small and mysterious animal found deep inside an unexplored tropical forest. Well, most of them fit in this description, but actually many new species are found living among humans for decades or centuries.

Many of them, while unknown to experts in the group, may be well known by the local people. An example of that is the recently described little black tapir (Tapirus kabomani).

But many species unknown to science are frequently spotted by nature enthusiasts and wildlife photographers. Fascinated by the beauty of the creatures they found, they take some pictures of the specimens and post them online. And when some biologist recognizes it as a probably new species, he or she gets excited and interested in helping that species to be known. A place crowded with new species is certainly flickr. Here I’ll show some photographs of land planarians, the group I work with, that I found on the website and that certainly, or most likely, represent new species.

Flatworm

Platyhelminthes, Tricladida, Terricola, Atlantic forest, northern littoral of Bahia, Brazil

(Platyhelminthes: Tricladida)

(Platyhelminthes: Tricladida)

Terrestrial flatworm (Geoplana sp)

Nemertean worm

Simona's 'Slug'

Sem título

Land Planarian

Unidentified Planarian: Loreto, Peru

Unidentified Planarian and Scorpion: Loreto, Peru

Large land flatworm

Land planarian Polycladus sp?

Oh, how I envy those people living close to these places! If only there were someone there able to study, described and publish all that diversity.

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Friday Fellow: ‘Orange Jaguar Snail’

by Piter Kehoma Boll

ResearchBlogging.orgLast week I introduced a land planarian that feeds on land snails, Obama ladislavii, or, as I called it, the Ladislau’s flatworm. Therefore, today, I thought it would be great to present a similar situation occurring backwards: a land snail that feeds on land planarians.

So let me introduce this little predator, the land snail Rectartemon depressus. Again, it is not a widely known species and thus it has no common names, but why not call it the ‘orange jaguar snail’? Species of the genus Euglandina, which are also predatory snails, are called ‘wolf snails’ by comparing them to a common predator in North America. As Rectartemon species are common in South America, we could perfectly call them ‘jaguar snails’, right?

Rectartemon depressus about to capture a land planarian Obama marmorata. Photo from Lemos et al., 2012

Rectartemon depressus about to capture a land planarian Obama marmorata. Photo extracted from Lemos et al., 2012

Found in areas of Atlantic Rainforest in Brazil, the orange jaguar snail has a yellow to orange body and a whitish shell. It is listed a vulnerable species in the Brazilian Red List, but it is not mentioned in the IUCN’s Red List.

Initially known as a predator of other land gastropods, the orange jaguar snail revealed a new item in its diet recently. During attempts to find the food items in the diet of some land planarians from southern Brazil, the orange jaguar snail was offered as a food option, but while the expectations were that the planarian would eat the snail, the opposite happened! After contacting the land planarian, the snail simply grasps it with its radula (the snail’s toothed tongue) and sucks it in very quickly, just as if it were eating a noodle!

The orange jaguar snail eagerly consumes several land planarians, both native and exotic species. It makes it one of the first known predators of land planarians. One of its prey is the Ladislau’s flatworm, so we have a snail that eats a flatworm that eats snails!

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References:

Lemos, V., Canello, R., & Leal-Zanchet, A. 2012. Carnivore mollusks as natural enemies of invasive land flatworms. Annals of Applied Biology, 161 (2), 127-131 DOI: 10.1111/j.1744-7348.2012.00556.x

Santos, S. B., Miyahira, I. C., Mansur, M. C. D. 2013. Freshwater and terrestrial molluscs in Brasil: current status of knowledge and conservation. Tentacle, 21, 40-42.

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Filed under Behavior, Conservation, Ecology, Friday Fellow

Friday Fellow: ‘Ladislau’s Flatworm’

ResearchBlogging.orgby Piter Kehoma Boll

Friday fellow is back!

After almost a year, I decided to go on with it. Actually, I interrupted it because of several other activities that were requiring my attention. Now let’s move on!

Today I will present to you another land planarian, and one I particularly like. Its binominal name is Obama ladislavii (formerly Geoplana ladislavii) and, as most land planarians, it does not have a popular name, although I suggest it to be ‘Ladislau’s Obama’ or ‘Ladislau’s Flatworm’. Now who is Ladislau?

Well, let’s first take a look at how this species was first described.

The Ladislau’s Flatworm was described in 1899 by the zoologist Ludwig von Graff in his famous monograph, “Monographie der Turbellarien”. Graff described it based on specimens sent to him from southern Brazil by the zoologist Hermann von Ihering, as well as on other specimens collected by the biologist Fritz Müller.

By the time Ihering and Müller were collecting specimens in Brazil, a botanist named Ladislau de Souza Mello Netto was the director of the Brazilian National Museum in Rio de Janeiro. He actually hired them as traveling naturalists, so we can say that he was the responsible for them being able to collect specimens in Brazil.

As a result, when describing this new planarian species, Graff decided to call it ladislavii in honor of Ladislau Netto. At least I think so! I did not find any reference to that, as Graff did not explain the etymology of the name in the description. However, whom else would ladislavii be referring to?

Now that we explained the name, it is time to talk about the worm itself.

Ladislau’s flatworm is found in southern Brazil’s states of Rio Grande do Sul and Santa Catarina and is easily recognized by its green color. The larger specimens can measure more than 10 cm in length and more than 1 cm in breadth while creeping, so it is a considerably large planarian for the local standards.

Obama ladislavii in all of its greenness. Photo by Piter K. Boll*

Obama ladislavii in all of its greenness. Photo by Piter K. Boll*

Most land planarians are found either in very well preserved ecosystems, for example, inside undisturbed forests, or in very well disturbed ecosystems, such as gardens and urban parks. Now we can find the Ladislau’s flatworm living very well both in a natural paradise in the middle of a dense forest as well as in that small garden beside a very busy street. How is that possible?

The life history of many land planarian species is completely unknown, so that we do not even know what they eat. They are recognized as important predators of other invertebrates, but that is not enough, as being a predator does not mean that you eat anything that moves, right?

Until recently, we knew very little about the Ladislau’s flatworm, but I started to study it along with other species in the last years and so now we at least have an idea of what it eats, and the answer is: Gastropods, i.e., slugs and snails!

We usually found gastropods in gardens, parks, plantations and everywhere humans plant something, so they are an available meal for the Ladislau’s flatworm. It feeds on many of those annoying little pests you may find in your garden, including the garden snail (Helix aspersa), the Asian trampsnail (Bradybaena similaris), and the marsh slug (Deroceras laeve).

Obama ladislavii and one of its snacks, the snail Bradybaena similaris

Obama ladislavii and one of its snacks, the snail Bradybaena similaris. Photo by Piter K. Boll*

The Ladislau’s flatworm can follow the slime trail left by the gastropod in order to find and capture it. The most efficient way for the planarian to subjugate the prey is by surrounding it with its body and using muscular power, not very different from what a constrictor snake does.

Considering its taste for those pests, the Ladislau’s flatworm seems to be a good item to have in your garden, right? Yes, but only if you live in southern Brazil. Exporting it to other areas can lead to catastrophic results, as the case you can read here.

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References:

Boll, P., & Leal-Zanchet, A. (2014). Predation on invasive land gastropods by a Neotropical land planarian Journal of Natural History, 1-12 DOI: 10.1080/00222933.2014.981312

Graff, L. v. 1899. Monographie der Turbellarien. II. Tricladida Terricola. Engelmann, Leipzig, 574 p.

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The New Guinea flatworm visits France – a menace

by Piter Kehoma Boll

ResearchBlogging.orgFor as long as life exists, it spreads. Organisms move (even if only as gametes or spores) and conquer new environments if they fit. If it wasn’t so, life wouldn’t be found all over the world. Recently, however, due to human dispersion, species are much more likely to reach places far away from where they were born. We considered a species living outside its native area as exotic. And there are a lot of them. I wonder if there is any place where no exotic species exist.

In my first post in this blog, I talked about how exotic species are not always a threat to native ecosystems. But many of them are, indeed, dangerous to local diversity. The ISSG (Invasive Species Specialist Group) lists what are considered the 100 worst invasive species. Strangely, they fail to mention the top worst invasive species, Homo sapiens.

Among those 100 species, a very famous one is the giant African land snail, Achatina fulica. Native to East Africa, it has been introduced worldwide and is a major pest in gardens and agricultural sites, and can also be an intermediate host of several parasites that infect humans.

The giant African land snail Achatina fulica. Photo by Eric Guinther. Extracted from commons.wikimedia.org

The giant African land snail Achatina fulica. Photo by Eric Guinther*. Extracted from commons.wikimedia.org

As an attempt to control the populations of Achatina fulica, some “genius” decided to introduce one more exotic species in the areas where A. fulica was a pest: a voracious generalist predator of land snails.

Let's fight against an exotic pest with another exotic pest!

Let’s fight against an exotic pest with another exotic pest!

As a result, the predator snail Euglandina rosea, known as the rosy wolfsnail or cannibal snail, was introduced in areas infested by A. fulica. But E. rosea is native to North America while A. fulica is native to East Africa. In order to be effective, E. rosea had to be a generalist predator, feeding on any kind of snails. And that’s what it does…

The rosy wolfsnail Euglandina rosea. Photo by Tim Ross. Extracted from commons.wikimedia.org

The rosy wolfsnail Euglandina rosea. Photo by Tim Ross. Extracted from commons.wikimedia.org

Euglandina rosea started to prey on A. fulica, but… ops! It also attacked native land snails and led several species to extinction in Pacific Islands. It became a pest even worse than the giant African land snail…

Not satisfied by the damage caused by this predator, people decided to introduce one more species in order to control A. fulica. And the chosen one was another voracious generalist predator of land snails, the New Guinea flatworm Platydemus manokwari. As its name suggest, thee New Guinea flatworm is native to New Guinea, again a different place, and so, in order to feed on the giant African land snail, it had to feed on any kind of land snail. Thus, it became a pest as harmful as the previous one and led several species of land snails to extinction in Pacific Islands.

Until very recently it was thought that the New Guinea flatworm infestation was restricted to the Indo-Pacific Region, not so far from home. However, a recent paper by Justine et al. (2014) reports its presence in a hothouse in Caen, northern France. This report extends significantly its occurrence over the world and indicates that it may be much more spread than previously thought. Unfortunately, people are more interesting in preserving their gardens than preserving biodiversity. So those predatory pests will probably keep being introduced as biological controls, even though they pose a threat to ecosystems.

The New Guinea Flatworm Platydemus manokwari. Photo by Pierre Gros, taken from Justine et al., 2014, via commons.wikimedia.org.

Bonjour tout le monde! I came to visit Paris! The New Guinea Flatworm Platydemus manokwari. Photo by Pierre Gros**, taken from Justine et al., 2014, via commons.wikimedia.org.

Fortunately, in France, P. manokwati seems to be restricted to greenhouses. Let’s hope that it won’t be found somewhere else.

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References:

Albuquerque, F., Peso-Aguiar, M., & Assunção-Albuquerque, M. 2008. Distribution, feeding behavior and control strategies of the exotic land snail Achatina fulica (Gastropoda: Pulmonata) in the northeast of Brazil. Brazilian Journal of Biology, 68 (4), 837-842 DOI: 10.1590/S1519-69842008000400020

ISSG, Invasive Species Specialist Group. 100 of the World’s Worst Invasive Alien Species. Availabe at: < http://www.issg.org/database/species/search.asp?st=100ss >. Access on April 04, 2014.

Justine, J., Winsor, L., Gey, D., Gros, P., & Thévenot, J. 2014. The invasive New Guinea flatworm in France, the first record for Europe: time for action is now. PeerJ, 2 DOI: 10.7717/peerj.297

Sugiura, S., Okochi, I., & Tamada, H. 2006. High Predation Pressure by an Introduced Flatworm on Land Snails on the Oceanic Ogasawara Islands. Biotropica, 38 (5), 700-703 DOI: 10.1111/j.1744-7429.2006.00196.x

Sugiura, S., & Yamaura, Y. 2008. Potential impacts of the invasive flatworm Platydemus manokwari on arboreal snails. Biological Invasions, 11 (3), 737-742 DOI: 10.1007/s10530-008-9287-1

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The lack of taxonomists and its consequences on ecology

by Piter Kehoma Boll

ResearchBlogging.orgI have already written on the problems of taxonomy in small and not-so-cute groups in a previous post, where I talked about the fact that several species, after being described, are completely ignored for decades or centuries. Here I will focus on the other extreme: the species yet to be described.

This is not a very big problem in very well studied groups, such as vertebrates and flowering plants, but less attractive groups, like worms, suffer a lot by the lack of taxonomists. I am going to use land planarians as an example, again, since it is the group that I work with.

Land planarians have been shown to be important predators of invertebrates in forests, as well as good indicators about the degree of disturbance in those ecosystems, but most species are still unknown. Only in Brazil, more than a hundred species have been described only for the Atlantic Rainforest and possibly at least an equal number is yet unknown. The situation is even worse in other regions of the country or neighbouring countries, where there are almost no species described at all.

Despite this small knowledge of the group, eventually some works regarding community structure are published, where a list of land planarians from the study site is presented. Let’s take a look at some of those lists:

1. Species of land planarians in four different habitats of the National Forest of São Francisco de Paula, southern Brazil. In Carbayo et al., 2001:

Carbayo et al. 2001

There are 28 distinguished species, but only one identified (Geoplana ladislavii), one not sure (Geoplana pavani) and two with the same name, but refering to different species (Notogynaphallia marginata). The others were yet unknown.

 

2. Species of land planarians in four different habitats of the National Forest of São Francisco de Paula, southern Brazil. In Carbayo et al., 2002:

Carbayo et al., 2002

A similar table, in the same area, by the same authors, about one year later. We can see 3 new species in the study: Geoplana franciscanaGeoplana josefi and Notogynaphallia guaiana, which were described in 2001. They were probably among the species listed in the first study, but which of them? Was Geoplana franciscana the species assigned as Geoplana sp.1, Geoplana sp.2, Geoplana sp.3…?

 

3. Abundance of species of land planarians in Araucaria Forest of the National Forest of São Francisco de Paula, southern Brazil. In Antunes et al., 2012.

Antunes et al., 2012

The same area again, 10 years later. We can see that there are more species already described, but many more still awaiting a name.

 

When we consider a single study about ecological communities by itself, the fact that the species found are not named is not such a big deal, since the main purpose is to measure patterns of abundance, richness and diversity and the interaction of biotic and abiotic factors on the communities. However, when comparing studies, the unidentified species become simply useless data. How can you be certain about what Geoplana sp.5 is in each study?

We urgently need more taxonomists working on those less prestigious groups, so that our ecological studies may have a wider role in conservation and understanding of nature.

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References:

Antunes, M., Leal-Zanchet, A. M. & Fonseca, C. 2012. Habitat structure, soil properties, and food availability do not predict terrestrial flatworms occurrence in Araucaria Forest sites. Pedobiologia, 55 (1), 25-31 DOI: 10.1016/j.pedobi.2011.09.010

Carbayo, F., Leal-Zanchet, A. M. & Vieira, E. M. 2001. Land planarians (Platyhelminthes, Tricladida, Terricola) as indicators of man-induced disturbance in a South Brazilian rainforest. Belgian Journal of Zoology, 131, 223-224

Carbayo, F., Leal-Zanchet, A. M. & Vieira, E. 2002. Terrestrial flatworm (Platyhelminthes: Tricladida: Terricola) diversity versus man-induced disturbance in an ombrophilous forest in southern Brazil. Biodiversity and Conservation, 11 (6), 1091-1104 DOI: 10.1023/A:1015865005604

Sluys, R. 1998. Land Planarians (Platyhelminthes, Tricladida, Terricola) in biodiversity and conservation studies. Pedobiologia, 42, 490-494

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