Category Archives: planarian

THE RACE: As the (Flat)worm Turns


Dr. Tom Daniel, senior botanist, demonstrating impressive intrepidity in a Sao Tome river. GG VII A.  Stanbridge phot.

In the earliest blogs we discussed how islands are ideal for studying certain evolutionary processes and patterns; some of these phenomena like gigantism and dwarfism (below) are actually characteristic of islands. And, the results of these processes are much easier to see on islands because of their smaller size (versus, say, continents) and the smaller size of the plant and animal populations that inhabit them.

begon giant

Worlds largest (left, Sao Tome) and smallest (right, Principe) Begonia. (RCD construct).

Invasive species are organisms that somehow become accidentally established in areas where they did not exist before; they can be hugely damaging to ecosystems especially on islands, that are made up of plant and animal species that have co-evolved in isolation over perhaps millions of years. In the absence of natural predators (checks and balances), invader populations can become numerous and spread rapidly, and this can have a devastating effect by exhausting the resources these species utilize in the local environment. Invasive animal species populations can burgeon hugely, and then frequently die off; by then, the damage is usually done.

good plan

(Phot. Miko Nadel, GG VII)

A few years ago, we received a photo of a brightly colored worm-like creature on São Tomé (above), taken by one of our graduate students, Miko Nadel, a lichenologist from San Francisco State University. This striped creature turned out to be a terrestrial flatworm, a member of a primitive phylum of invertebrates called the platyhelminthes. Those of us lucky enough to study biology backwhen students were given actual organisms to observe rather than plastic models or video clips will remember “planarians,” aquatic flatworms (below) noted for their amazing ability to regenerate.

Dugesia planarian

Planarian (Dugesia) . Stock photo, Google photos.

planarian regen. U Heidelberg
Flatworm regeneration. (Univ. Heidelberg photo.

Terrestrial flatworms, also known as geoplanids have no anatomical or physiological mechanisms for retaining water and are thus very much tied to moist environments. They are voracious predators upon other soil invertebrates such as earthworms, slugs and, most importantly for us, snails. Geoplanids secrete a mucus that begins to digest and dissolve their prey externally (below), and all geoplanid species known feed using an extendable digestive tube or pharynx.

new geoattackGeoplanid attacking a snail. (R. Lima, phots)


As above, at Macambrara, Sao Tome. [Phot S. Mikulane]

Once aware of these, we began to notice more of them as did our ecologist colleague, Dr. Ricardo Lima, and we all became rather concerned. Why? Readers may recall that about half to 60% of all of the species of terrestrial mollusks (snails) of both São Tomé and Príncipe are endemic; i.e., they are found nowhere else in the world.

x new

[RCD construct-multiple photographers]

In fact, these snails have been isolated on the island and evolving for such a long period that scientists currently recognize six different genera and a unique snail family there! Given what we know about invasive species, if these geoplanids are indeed a new arrival then the unique snail fauna of the islands may well be in significant danger.



Another geoplanid [phot. F. Azevedo]

In 2012, we sent the original specimen to Dr. Ronald Sluys of Naturalis Biodiversity Centre in Leiden, Holland, one of the few specialists on flatworms. In the meantime, Dr. Ricardo Lima (below) has been conducting ecological research on the São Tomé forests for several years and has been able to collect many more geoplanids and send them to Dr. Sluys.

When the GG IX team visited Dr. Lima at Monte Café, São Tomé last year, he showed us pictures of a number of very different looking morphs of flatworms that he had collected and sent to Dr. Sluys. Were these different species or just variations on one or two species (morphs)?

various geos

Various geoplanids from Sao Tome [phots R. Lima, F. Azevedo, M. Nadel, R. Rocha]

Ron Sluys has been supervising a graduate student from the University of Kassel, Germany who is doing his MSc degree based on this material. His name is Matthias Neumann and as I write, he is on the island of São Tomé with Dr. Lima, studying the flat worms in situ and collecting more! We were able to fund his expedition with the Academy’s Gulf of Guinea Fund (see “Partners”, below).


Matthias Neumann and partner in the bush on Sao Tome. [R. Lima phot]

Matthias’ preliminary work suggests that there are indeed a number of species of geoplanids on the island: at least five new, undescribed species of the genus Othelosoma, and another previously known species, Bipalium kewense. B. kewense is an extremely widespread species, presumably carried about in the roots of plants; evidently it preys on earthworms rather than snails.

So far, little is known of these strange creatures. Neumann says that at least two of the undescribed species of Othelosoma are snail predators but even so, the presence of a number of species on the island rather than one dominant, rapidly spreading one might be taken as somewhat reassuring. If there are a number of closely related members of the same flatworm genus, it is more likely that the common ancestor of these species arrived a long time ago, speciated, and thus co-evolved with the endemic snail fauna. If this is so, than we would expect an ecological predator/prey balance in this system. If the flatworm fauna is in fact a radiation from a given colonizer, then it would mirror the status of the earthworm fauna as we understand it (below). So far, we are uncertain whether geoplanids are present on Príncipe.












We are in the planning stages for GG XI; see the next blog.

The Parting Shot:









A local teacher assists us in a binoculars demonstration on Sao Tome, GG IX. Dr. Luis Mendes in background.  [phot. A. Stanbridge]


The research expeditions and the primary school education program are supported by tax-deductable donations to the “California Academy of Sciences Gulf of Guinea Fund”* We are grateful for ongoing governmental support, especially to Arlindo de Ceita Carvalho, Director General, Victor Bomfim, and Salvador Sousa Pontes of the Ministry of Environment, Republic of São Tomé and Príncipe for their continuing authorization to collect and export specimens for study, and to Ned Seligman, Roberta dos Santos and Quintino Quade of STePUP of Sao Tome, our “home away from home”. GG VIII, IX , X and upcoming GG XI have been funded by a generous grant from The William K. Bowes Jr. Foundation, and substantial donations from Mrs. W.H.V.“D.A.” Brooke, Thomas B. Livermore, Rod C. M. Hall, Timothy M. Muller, Prof. and Mrs. Evan C. Evans, Mr. and Mrs. John L. Sullivan Jr., Clarence G. Donahue, Mr. and Mrs. John Sears, and a heartening number of “Coolies”, and members of the Docent Council of the California Academy of Sciences. Once again we are deeply grateful for the support of the Omali Lodge (São Tomé) and Roça Belo Monte (Príncipe) for both logistics and lodging and for partially sponsoring our education efforts for GG VII and GG VIII.

*California Academy of Sciences
55 Music Concourse Dr.
San Francisco, CA 94118



The Race: Flatworms, a New Doctor and an Island Education Video

One of our most consistent and knowledgeable colleagues on the island of São Tomé has been Ricardo Lima, up until recently a graduate student at the University of Lancaster.


Ricardo Lima crossing the Rio Lemba, Sao Tome. (unknown phot)

Ricardo has been studying the effects of land use changes on the distribution of the endemic birds of São Tomé, and I am delighted that (1) he has just completed his PhD, (2) he has published a fine article on his research in the journal Diversity and Distribution, and (3) he is back on the big island having found funding for the continuation his research. This funding will also allow the reprinting of the biodiversity posters we distributed during GG V in 2011.Readers will recall we were able produce only 200 of these (see March – April 2011 posts).


Dr. Ricardo Faustino de Lima being savaged by a Sao Tome malachite kingfisher (unknown phot)

Over the several years I have known him, Ricardo has sent us images and/or specimens of great interest to us both, including a freshwater fish we missed in our 2001 and 2006 river surveys (we still have not analyzed one), and especially the specimens of the endemic shrew, Crocidura thomensis which we subsequently studied genetically.Dr. Lima will be one of the authors when the shrew paper is completed.A year or so ago, Ricardo sent us some pictures of a strange, brightly colored flatworm called a terrestrial planarian or geoplanid.


Terrestrial planarian (geoplanid) (R. Lima phot.]

As delicate as these little terrestrial creatures appear, they are actually voracious predators upon snails, slugs, insects and earthworms.The known species have very narrow, specific habitat preferences and thus can be used as indicators of habitat types. Readers will recall that over 60% of the snails of São Tomé and Príncipe are found nowhere else in the world, including an endemic genus, Bocageia; if this geoplanid is an invasive, it may well be a real threat to the populations of endemic snails.


Terrestrial planarian (geoplanid) (R. Rocha phot.)

Even with a better image in hand (above) we could not put a name on this animal. We have many experts here at CAS, but none specializes in this class of invertebrates, the Platyhelminthes.During GG VI last April, Miko Nadel, our lichenologist graduate student collected a specimen way up at 1700 meters on Pico do São Tomé (see Mountains that Glow, April 2012) and brought it back.


Miko Nadel (l) and Jim Shevock on Sao Tome [A. Stanbridge phot. GG VI]

Now with a specimen in hand, we needed to find an expert.Thanks to Dr. Shannon Bennett, Head of our Department of Microbiologist, we discovered Dr. Ronald Sluys, of the Netherlands Centre for Biodiversity Naturalis. Dr. Sluys has been sent the specimen and is “willing to give it a try!”.Apparently, there are not all that many experts in this field, and Ron says he will have to section our one specimen with a microtome in order to try to identify it.If it is new, we will try to get more for him; if it has a name, we can add yet another species to the remarkable biota of the islands.

Finally, our readers will know that since GG IV in 2010 we have been developing a biodiversity education program for the youth on both islands.Our volunteer group has put together a video describing the bio-ed project; this will be the first time I have tried to post a video on this blog.It is about 7 minutes long, and if it works, my thanks to Jim Boyer for his expertise.

Please click on this link:

Here’s the parting shot:


Picos Joao Dias Pai e Filho (father and son), Principe [T. Daniel phot. GG IV)

We gratefully acknowledge the support of the G. Lindsay Field Research Fund, Hagey Research Venture Fund of the California Academy of Sciences, (GG I, II), the Société de Conservation et Développement (SCD) and Africa’s Eden for logistics, ground transportation and lodging (GG III-V), STePUP of Sao Tome, Arlindo de Ceita Carvalho, Director General, and Victor Bomfim, and Salvador Sousa Pontes of the Ministry of Environment, Republic of São Tomé and Príncipe for permission to collect and export specimens for study. Special thanks for the generosity of private individuals who made the GG III-V expeditions possible: George G. Breed, Gerry F. Ohrstrom, Timothy M. Muller, Mrs. W. H. V. Brooke, Mr. and Mrs. Michael Murakami, Hon. Richard C. Livermore, Prof. & Mrs. Evan C. Evans III, Mr. and Mrs. Robert M. Taylor, Velma and Michael Schnoll, and Sheila Farr Nielsen; GG VI supporters include HBD of Bom Bom and the Omali Lodge for logistics and lodging, The Herbst Foundation, The “Blackhawk Gang,” the Docent Council of the California Academy of Sciences in honor of Kathleen Lilienthal, Bernard S. Schulte, Corinne W. Abell, Prof. & Mrs. Evan C. Evans III, John and Judy Sears, John S. Livermore and Elton Welke.
Our expeditions can be supported by tax-deductable donations to “California Academy of Sciences Gulf of Guinea Fund”.