We learned last week about the giant African snail and how it spread around the world, harming several ecosystems. By the beginning of the 1980s, the giant African snail was a pest on the island of Guam, but suddenly its numbers started to drop and the cause was the accidental introduction of another species on the island, the New Guinea flatworm, Platydemus manokwari.
Discovered in the forests around the city of Manokwari in New Guinea, more precisely in the province of West Papua, Indonesia, the New Guinea flatworm were at first just another land planarian like many others found around Australasia and the Indo-Malaya ecozones. Measuring about 60 mm in length, 7 mm in width and only 2 mm in thickness, the New Guinea flatworm has a dark-brown, almost black dorsum with a fine yellow median line, while the ventral side has a beige color. Belonging to the tribe Rhynchodemini of land planarians, it has only two eyes near the anterior end and they are considerably large compared to the eyes of land planarians of other tribes and subfamilies and even have a simple lens over their pigment cup, meaning it probably sees better than most planarians.
As all, or most, land planarians, the New Guinea flatworm is a predator and its favorite prey seems to be snails, which made it become a successful control method against the giant African snail in Guam. Due to this success, the New Guinea flatworm was deliberately introduced in Bugsuk, a small island of the Philippines. About 20 months after its introduction, its population had grown significantly and the population of the giant African snail had sharply decreased.
During the following years, the interested in the New Guinea flatworms as biological control increased and the species was introduced either deliberately or accidentally in many Pacific islands. However, around the 1990s, the situation has already turned into a nightmare. One of the most severely affected areas were the Ogasawara Islands in Japan. These islands used to have a very rich snail fauna but 10 years after the introduction of the New Guinea flatworm, most species were extinct. However, despite removing most snails from the islands, the population of the New Guinea flatworm continued to be large and soon it was discovered that it could also feed on earthworms, nemerteans, woodlice and even other land planarians. Its threat, therefore, goes way beyond the snails.
Although widespread across many Pacific islands, the New Guinea flatworm remained restricted to this area of the world for some time, but things changed in 2014 when it was reported in France. Only one year later, in 2015, it was found in the southern United States and the Caribbean. By 2018 it was recorded in Thailand and, to turn things worse, it revealed to be another host of the parasitic nematode Angiostrongylus cantonensis, just like the giant African snail.
It should come as no surprise that the New Guinea flatworm is also considered one of the top 100 invasive species. Its recent spread across Europe and the Americas means that a new wave of extinctions caused by our recklessness it about to begin.
Chaisiri, K., Dusitsittipon, S., Panitvong, N., Ketboonlue, T., Nuamtanong, S., Thaenkham, U., Morand, S., & Dekumyoy, P. (2018). Distribution of the newly invasive New Guinea flatworm Platydemus manokwari (Platyhelminthes: Geoplanidae) in Thailand and its potential role as a paratenic host carrying Angiostrongylus malaysiensis larvae. Journal of Helminthology, 1–9. https://doi.org/10.1017/S0022149X18000834
Justine, J.-L., Winsor, L., Gey, D., Gros, P., & Thévenot, J. (2014). The invasive New Guinea flatworm Platydemus manokwari in France, the first record for Europe: Time for action is now. PeerJ, 2, e297. https://doi.org/10.7717/peerj.297
Justine, J.-L., Winsor, L., Barrière, P., Fanai, C., Gey, D., Han, A. W. K., La Quay-Velázquez, G., Lee, B. P. Y.-H., Lefevre, J.-M., Meyer, J.-Y., Philippart, D., Robinson, D. G., Thévenot, J., & Tsatsia, F. (2015). The invasive land planarian Platydemus manokwari (Platyhelminthes, Geoplanidae): Records from six new localities, including the first in the USA. PeerJ, 3, e1037. https://doi.org/10.7717/peerj.1037
Kawakatsu, M., Oki, I., Tamura, S., Itô, H., Nagai, Y., Ogura, K., Shimabukuro, S., Ichinohe, F., Katsumata, H., & Kaneda, M. (1993). An extensive occurrence of a land planarian, Platydemus manokwari de Beauchamp, 1962, in the Ryûkyû Islands, Japan (Turbellaria, Tricladida, Terricola). 陸水生物学報 (Biology of Inland Waters), 8, 5–14.
Muniappan, R., Duhamel, G., Santiago, R. M., & Acay, D. R. (1986). Giant African snail control in Bugsuk island, Philippines, by Platydemus manokwari. Oléagineux, 41(4), 183–186.
Ohbayashi, T., Okochi, I., Sato, H., & Ono, T. (2005). Food habit of Platydemus manokwari De Beauchamp, 1962 (Tricladida: Terrricola: Rhynchodemidae), known as a predatory flatworm of land snails in the Ogasawara (Bonin) Islands, Japan. Applied Entomology and Zoology, 40(4), 609–614. https://doi.org/10.1303/aez.2005.609
A few days ago I saw a photo of some giant African snails and though “that’s an interesting species to feature as a Friday Fellow”, and to my surprise a gastropod was scheduled to be presented today, so voilà, let’s talk about Lissachatina fulica, the Giant African Snail.
As the popular name implies, this land snail is native from Africa, more precisely East Africa, around Kenya and Tanzania, and it is quite large, with adults measuring 20 cm or more in length and about 7 cm in height. The shell is conical and very hard and has a marmorated brown and white color and a sharp border around its opening.
The Giant African Snail is able to feed on a huge variety of plants and can sometimes even consume dead animals, paper and even stones. As a result, it is very adaptable to new areas and has become invasive in many regions of the world, especially tropical areas in Asia, South America and the Pacific.
These snails are hermaphrodites but when mating they can act only as male, only as female or as both and this is usually related to the size of both snails. If they are similar in size, they transfer sperm to each other. If they have different sizes, the smaller snail act as a male and the larger one as a female. A “female-acting” snail can store sperm up to two years to fertilize eggs as they are produced. Thus, a single mated “female” can create an entire population if transported to a new area as it can lay around 200 eggs per clutch and produce about five to six clutches per year.
The Giant African Snail is edible and used as a food source by some African peoples. A similar species, Archachatina marginata, native from Nigeria, is offered to West African deities which in Brazil led to the development of Candomblé. However, as this species is not found in Brazil, it is replaced by Lissachatina fulica, which has been introduced in this country. Recently it has become considerably popular as a pet as well. This species has also been studied for medical use and an antimicrobial compound has been isolated from its mucus.
Especially due to its use as a food source, but also accidentally, the Giant African Snail has ben introduced in many places around the world and has become a threat to tropical ecosystems because of its voracious behavior, where it competes with native snails for food resources. Due to the need to feed on calcium to build their shell, these snails can also end up eating calcium-rich material in buildings and cause severe damage to the structures.
More than that, the Giant African Snail can harbor a parasitic nematode, Angiostrongylus cantonensis, which causes a very serious meningitis in humans. Most cases of humans being infected by this nematode is the result of eating the snails raw, but there is a small chance of getting infected even by only manipulating the snails.
Due to so many damaging outcomes from the introduction of this species around the planet, it is considered one of the top 100 invasive species of the world. Some attempts to control invasive populations using biological agents have failed miserably and only worsened the whole scenario. Next week I will present one of those failures.
Graeff-Teixeira, C. (2007). Expansion of Achatina fulica in Brazil and potential increased risk for angiostrongyliasis. Transactions of the Royal Society of Tropical Medicine and Hygiene, 101(8), 743-744. https://doi.org/10.1016/j.trstmh.2007.03.012
Thiengo, S. C., Faraco, F. A., Salgado, N. C., Cowie, R. H., & Fernandez, M. A. (2007). Rapid spread of an invasive snail in South America: the giant African snail, Achatina fulica, in Brasil. Biological Invasions, 9(6), 693-702.
We see grasses all the time around us but we barely pay attention to them, even though they form one of the most diverse plant families in the world. Today I’m presenting one of them, one that actually grows all around my parents’ house making up the lawn. Its scientific name is Axonopus compressus and its common name is often Broadleaf Carpetgrass.
This species is native from southern USA to northern Argentina. As all, or most, grass species used as lawn, it has a creeping habit, with shoots that come out of the subterranean rhizomes spreading horizontally over the soil. It has relatively broad and soft leaves for a grass, without much hair, and often a reddish tinge on the creeping “branches”. The inflorescences form narrow spikes that occur in groups of 2 to 3, sometimes up to 5, in the single branch that comes out from the top of a stalk that can be up to 60 cm tall. Sometimes more than one inflorescence comes out of the same stalk.
Due to the fact that the broadleaf carpetgrass grows too close to the soil, it is not popular as a food source for cattle. However, it is very common as lawn, especially because it is very tolerant to both drought and floods, full sun or shadow. It can also be used for football fields, although it is not considered an ideal species for that.
Although native to the Americas, the broadleaf carpetgrass has been introduced in Africa, Asia and Australia and became a weed of considerable importance in some places. Even though it does not grow and spread as quickly as other grasses, it often is able to survive and sometimes even outcompete other species due to its resistance to a broad range of environmental conditions.
Several studies have indicated that the broadleaf carpetgrass can be used as an efficient agent to reduce the pollution of contaminated soils and grey water. Recent studies have also focused on the genetics of this species to understand its phylogenetic relationships and the mechanisms responsible for its remarkable resistance.
Although usually an “invisible” organism that is very present around us, the broadleaf carpetgrass is very useful to humans for a variety of purposes and probably many more are still to be discovered.
Arunbabu, V., Sruthy, S., Antony, I., & Ramasamy, E. V. (2015). Sustainable greywater management with Axonopus compressus (broadleaf carpet grass) planted in sub surface flow constructed wetlands. Journal of Water Process Engineering, 7, 153-160. https://doi.org/10.1016/j.jwpe.2015.06.004
Bordoloi, S., Basumatary, B., Saikia, R., & Das, H. C. (2012). Axonopus compressus (Sw.) P. Beauv. A native grass species for phytoremediation of hydrocarbon‐contaminated soil in Assam, India. Journal of Chemical Technology & Biotechnology, 87(9), 1335-1341.
He, L., Liao, L., Wang, Z., & Wu, Y. (2020). The complete chloroplast genome of Axonopus compressus (Sw.) Beauv. and its phylogenetic position. Mitochondrial DNA Part B, 5(2), 1441-1442. https://doi.org/10.1080/23802359.2020.1735951
Ighovie, E. S., & Ikechukwu, E. E. (2014). Phytoremediation of crude oil contaminated soil with Axonopus compressus in the Niger Delta Region of Nigeria. Natural Resources, 2014. doi: 10.4236/nr.2014.52006
Hey there, Earthling! I felt like posting something special for the blog, but since we’re still a few months away from our 10th anniversary, I’ll just do it now; today I bring a special article about a special subject: Speculative Evolution. For those who are unfamiliar with what this is, it’s simply a creative movement that is equal parts art and science, and based on questions such as “how would evolution work if things happened differently?”, “how will life look like millions of years into the future?” and even “what forms will X living being produce in given parameters?”. And while such thought-experiment is done purely for the sake of entertainment, it does provide a fun way to learn and understand how evolution and its processes function and influence life, and one might even say it can allow us to predict what we might encounter in the fossil record – more on that later!
It’s a field not so dissimilar from exobiology art, of which the focus is imagining life in other planets, and which can be a bit of an anything-goes scenario given the extreme parameters that exoplanets may produce and sheer variety of such in the known cosmos, though in some cases it really depends on how willing the artist is to deviate from the Terran paradigms; in this case, however, we’re specifically talking about alternative evolution routes for Earth’s living beings, either from the past or from the present towards the future, and it’s arguably one of the most alluring movements for creative minds who can’t help but imagine a biosphere of their own design – it’s a very big part of what made the EN group become friends.
Its popularity has gradually grown in no small part due to the works of the Scottish geologist, paleontologist and prolific dinosaur book writer Dougal Dixon, with his famous trilogy of speculative evolution consisting of “After Man: A Zoology of the Future” (1981), “The New Dinosaurs: An Alternative Evolution” (1988) and “Man After Man: An Anthropology of the Future” (1990), later as well working as consulter and creature designer for the later TV series “The Future is Wild” (2002), which was responsible for the resurgence of interest in this area by bringing a relatively more up-to-date take on the subject. With the growing presence of the internet at the time, Speculative Evolution flourished to create a fandom of its own sometime around the mid-2000s.
The result of this fanatical writing made a text so long that I decided to make it into a three-parter special:
-The first part, which you’ll read in this post, will tell you about the works that first explored the theme – most in passing – and were released before After Man.
-The second part focuses solely on Dougal Dixon’s trilogy of After Man, The New Dinosaurs, and Man After Man, and marked the de facto birth of Speculative Evolution as a genre since they were the first purposely-made works on the subject available to a global-scale public.
– The third part will talk about the works that came after Dixon’s trilogy and were influenced by it, primarily The Future is Wild, as well as more recent takes on the subject, and what the future might hold for the genre.
So with all that said, let’s explore where all of this comes from, going back to the very birth of evolutionary thought:
-Darwin’s ponders on the speculative evolutions of the bear (and fish)
This may come as a surprise to some, but Charles Darwin himself, the father of modern biology and evolutionary science, and the one who proposed the concept of natural selection and the gradual change of species through time, was one of the first scientific minds to write about the core concept of speculative evolution in some shape and form.
In the first edition of his well-known book “The Origin of Species” (1859), Darwin describes the following:
“In North America the black bear was seen . . . swimming for hours with widely open mouth, thus catching, like a whale, insects in the water. Even in so extreme a case as this, if the supply of insects were constant, and if better adapted competitors did not already exist in the country, I can see no difficulty in a race of bears being rendered, by natural selection, more and more aquatic in their structure and habits, with larger and larger mouths, till a creature was produced as monstrous as a whale.”
This excerpt was removed from the second edition due to the controversial nature of the statement, as many scoffed at the idea of a bear becoming a whale (which is, of course, absurd, since they evolved from hoofed mammals); however, this suggests that Darwin thought of how evolution, as a factual process and in an out-of-the-box approach, could, if given enough time and with the proper set of circumstances, cause a modern animal to become a fictional species with an entirely new appearance and lifestyle. That in itself is the basis of speculative evolution, and as far as anyone is concerned, it may very well be the first account of such, unlike the erroneous notions of the Lamarckian theory.
Furthermore, Darwin also pondered on the same process applied to the development of the flying-fish into becoming a creature capable of true flight. If it sounds too familiar a description, don’t worry, we’ll look into it later on:
“Seeing that a few members of such water-breathing classes as the Crustacea and Mollusca are adapted to live on the land, and seeing that we have flying birds and mammals, flying insects of the most diversified types, and formerly had flying reptiles, it is conceivable that flying-fish, which now glide far through the air, slightly rising and turning by the aid of their fluttering fins, might have been modified into perfectly winged animals. If this had been effected, who would have ever imagined that in an early transitional state they had been inhabitants of the open ocean, and had used their incipient organs of flight exclusively, as far as we know, to escape being devoured by other fish?”
While the idea of strange and unusual creatures inhabiting the world has always been commonplace in human culture since ancient times, they always had a fantastic and magical aspect to them, often outright breaking the laws of physics and biological understanding, which is a radically different approach of imagining life from the point of view of speculative evolution, which roots its principles on factual processes to produce fanciful life forms but with a depth of truth to them.
It’s also worth noting that creationism was the prevalent model even for scientific fields in Darwin’s time: for paleontology at its infancy, the concept of a world millions of years old, if not billions, was unfathomable, and the skeletons of creatures long gone were thought to be that of “antediluvian” monsters that inhabited the planet along with humans and regular modern animals and where correlated to the biblical mythological beasts, and contributing for such idea is the fact that their bones were frequently found buried in sedimentary rocks, suggesting they were buried by such events like a worldwide flood. This vision was challenged only after Darwin’s ideas were published and science began to be more objective, separating itself from religious views in the search for evidence to understand the natural world and its history.
Even after the notion of extinction broke free from the stigma of going against the image of an infallible creator figure, for a time science proceeded shyly to try and explain the strange creatures analyzed and the absurd picture they painted in a reasonable manner, as the fossil record of the time didn’t provide a very clear idea of what had transpired in our world in ages past. As more and more material was found and established the progression of how living things evolved and had gone extinct, science was able to produce a much more familiar timeline for the modern reader in the early 20th century and understand how certain creatures came to be – even us.
-Early speculative evolution ideas with H. G. Wells
The classic book by the British writer H. G. Wells, “The Time Machine” (1895), can be considered what sprung the entire idea of time travel, as well as life developing after the present day to the wider media – even Dixon himself cites this work as being the inspiration behind After Man.
Other than the prominent Eloi and Morlocks, both having evolved from modern day humans hundreds of thousands of years after modern times, the book also describes a few other creatures which are a bit tame by today’s standards in sci-fi settings: the world 30 million years hence is apocalyptical, covered in lichens and inhabited by giant arthropods similar in appearance to crabs, butterflies and nautiloids.
Yet, due to the narrative nature of the work, there’s not much objective approach to the life forms described: the human descendants do possess physical and behavioral differences from their ancestors, but the circumstances that brought about these changes are superficial and seemingly included as a literary device for social commentary (that is, considering the material from the prequels, which detail the exact origins of the Eloi and the Morlocks), and the creatures from the far future seem to be created rather for shock value than any objective rationalization of why and how these forms came into existence (furthermore, material removed from the original and later on added again mention some more forms, and seemingly indicate that the creatures seen in the far future are in fact the descendants of the Morlocks and Eloi).
That’s not to discredit the notion of life existing million of years into the future being established, even if it does seem much grimmer than what most would consider for a scenario that “near” into the future nowadays, being something more suitable to several hundred million years in modern speculative evolution, and regardless it is a pretty good bet that creatures of arthropod characteristics would rule the world the further one travelled towards the future.
Just, you know, they wouldn’t be evolved from humans.
“The Time Machine” had, of course, various film adaptations, some of which actually removed much of the speculative elements in the original or otherwise didn’t give it a lot of attention, most glaringly the Eloi being portrayed as regular people in stature and appearance as opposed to their Hobbit-esque incarnations from the books (though it’s perfectly understandable why they changed it).
– More ideas of future evolution for humans with Olaf Stapledon
While the idea of humanity evolving into new species was already introduced with “The Time Machine”, a more elaborated take on the subject, if a more fantastic one, was presented with British philosopher and sci-fi writer Olaf Stapledon’s book, “Last and First Men” (1930), which chronicles the future of humanity in the span of 2 billion years.
As you can imagine, the sci-fi aspect has a pretty heavy influence on the concept given the unreasonable amount of time covered and the future humans varying greatly in appearance – one being a gigantic brain, while another is shaped like a bat – and some very early use of the idea of genetic engineering being employed. Sadly, the species featured weren’t illustrated as frequently as the ones from H. G. Wells’ work.
And while the book was a great success upon release and has had a lasting impact in the sci-fi, its Speculative Evolution side seemingly didn’t receive much attention, with the core idea of human evolution only resurfacing in force 60 years later with “Man After Man”, and to this day it’s one of the less explored scenarios of the field, although it does come up from time to time.
It’s also a work I haven’t heard about until recently so I don’t have a lot to say about it, but it’s intriguing to think that the subject was a already a thing, and in the 30s of all things.
– The Rhinograndentia parody
A rather unusual and comical part of speculative evolution history, the snouters, or nasobames, or Rhinograndentia, were created long before the publishing of After Man, by the German zoologist Gerolf Steiner (a most irreverent figure whose actual photos are impossible to find), published as a book entitled “Bau und Leben der Rhinogradentia” (1957) or “The Snouters: Form and Life of the Rhinogrades” in its English translation. The entire concept was inspired by the 1905 poem “The Nasobame”, by German writer Christian Morgenstern, a nonsensical text which describes a creature that walks with its many noses.
The book is basically a literary mockumentary, presenting itself as the official translation of the only remaining document on the now-submerged Pacific archipelago of Hy-yi-yi and its unique fauna by the intrepid zoologist Harald Stümpke. Said archipelago vanished from the map due to an atomic bomb test, which also vanquished all the other researchers on the Rhinograndentia that were holding a meeting in one of the islands at the time of the catastrophe.
Despite the comedic nature of the work, Steiner was able to create a rather convincing plethora of life forms of all shapes and sizes to fill in the archipelago’s unusual ecosystems, applying a great deal of his academic knowledge of zoology to create a fauna that arguably isn’t any weirder than some real animals, and adding to the realism of the work is a bit of jest from Steiner’s part by showing “evidence” of the existence of the Rhinograndentia, with various models of supposedly “stuffed specimens” exhibited at the Wiesbaden Museum in Germany, no doubt confusing and amusing lots of visitors who don’t know any better.
It also helped that Steiner treated them as real, and maintained the ruse un til the end.
Compared to other speculative evolution works, the Rhinograndentia is usually left out of the spotlight most likely due to its lighthearted humor and bizarreness, not to mention its limited release outside of Germany, and maybe because it’s less about actual future or alternative evolution and more of a “lost world” type of fiction, but I still find it worth talking about, especially given the lengths Steiner (which sadly has passed away in 2009) went to make a museum collection of said creatures.
And with that, we reached the end of Part 1! As you can see Speculative Evolution had existed for longer than one would imagine, albeit not identified by this name, but I hope you enjoyed reading on what preceded the works of Dougal Dixon before we tackle them on Part 2!
Today we will deal with one of the classics again. Spongia officinalis, or bath sponge, is a species that has been used by humans for millenia. Belonging to the class Demospongiae, the bath sponge is the origin of the name sponge.
The bath sponge is found in the Mediterranean from a depth of 1 to 100 meters. It grows on rocks and sand in well-oxygenated waters, forming gray-colored lumps whose shape can vary considerably. Due to its sessile habits, Linnaeus originally classified it as a plant, which can still be noticed in its name, as officinalis was a common epithet used by Linnaeus to refer to plants that were edible, medicinal or otherwise useful to humans.
As most sponges, the bath sponge feeds on floating organic particles and microorganisms, which it filters by pulling water inside its body through small pores and releasing it through larger openings, the oscula. They can reproduce either asexually by budding and fragmentation or sexually. Bath sponges can be either hermaphrodites or only have one sex, or even alternate between being male and female. Sexual reproduction occurs more often from October to November, when “male-behaving” sponges release sperm into the water, which is captured by “female-behaving” ones and transported to their eggs, where fertilization occurs. The embryo starts its development inside the mother and is eventually released to settled on the substrate and develop into a tiny version of an adult sponge.
The skeleton of the bath sponge makes it a flexible but resistant material, and dead and dried specimens have a good absorptive potential. Humans have explored these properties since ancient times, starting in Greece and later spreading through the whole Mediterranean and in modern times even to the whole world. As the common name implies, the main use of the bath sponge is in bath and other cleaning activities, just like modern synthetic sponges are used. They can also be used as an absorbent material and even as a tool for painting.
Despite being a common species in the Mediterranean, its harvesting since ancient times have severely depleted some populations and even led to local extinctions. As a result, its harvesting is forbidden or limited in some areas and interested in sponge farms have increased in recent years. The cultivation of sponges together with fish seems to be a good practice because, as sponges as filter feeders, they also help remove pollutants from water.
Have you ever used a genuine bath sponge to bathe or in other activities?
Today’s species cause mixed feelings in humans. Named Ustilago maydis, it is known as the corn smut.
A fungus, the corn smut belong to the division Basidiomycota, the same that includes the most famous mushrooms (apart from truffles and morells, which are of the division Ascomycota). As the name of the corn smut implies, it is a species associated with corn, i.e., maize, being a parasite of this important crop.
The life of the corn smut begins in the form of sporidia, single-cell organisms that grow on the surface of corn plants by budding off daughter cells in a way that resembles the growth of a yeast. When two compatible sporidia meet on the surface of the plant, they produce conjugation tubes through which they fuse and give rise to hyphae, the multicellular stage that makes up the mycelium, i.e., the mass of filaments that form the “body” of the fungus.
The hyphae grow by penetrating the corn plant and feeding on its tissues, which causes chlorosis (insufficient chlorophyll), reduced growth and eventually the formation of tumors, which often appear on the corns.
The tumors harbor the teliospores, a resting spore-stage. When the tumor is mature, it releases the teliospores, which will develop into a basidium under appropriate conditions. The basidium then originates new sporidia, which are released and restart the cycle.
The tumors caused by the corn smut are edible and, in Mexico, they are considered a delicacy and known by the name huitlacoche. The price of those tumors is much higher than that of regular corn and is used in several recipies as a filling and in soups. Huitlacoche is particularly rich in lysine, one of the essential amino acids for humans. Despite this “advantages” of the corn smut as a food source, it is still a problematic corn disease wordlwide, as it can cause losses above 30% in infected crops.
The conflict between the corn smut and corn plants led to amazing evolutionary developments in both organisms. Corn plants usually respond to corn smut infections with oxidative burst, which is the production of large quantities of reactive oxygen species at the site where the fungus is trying to invade. This oxidative burst cause lots of damage to the fungus’ DNA but, as a response, the corn smut developed a rather effective recombinational DNA repair system.
Due to this strong evolutionary pressure to bypass the plant defense systems, the corn smut is becoming a new model organism to study plant-pathogen interactions. This is increased by the fact that it is a well-suited organism for genetic modification and its entire genome has already been sequenced. The study of its DNA-repair mechanisms can also lead to the development of new DNA-repairing tools and may assist in new technologies to fight against cancer.
Sometimes humans turn an original nuisance into a new oportunity to thrive because… humans. We are kind of the mammal equivalent of a cockroach afterall, aren’t we?
Kämper, J., Kahmann, R., Bölker, M., Ma, L. J., Brefort, T., Saville, B. J., … & Birren, B. W. (2006). Insights from the genome of the biotrophic fungal plant pathogen Ustilago maydis. Nature, 444(7115), 97-101. https://doi.org/10.1038/nature05248
The diversity of animal life on Earth is so big that even after 270 Friday Fellows we still have new phyla to introduce. Today I introduce Echinoderes hwiizaa, which I decided to call the goat mud dragon.
Mud dragon is the common name of animals in the phylum Kinorhyncha. This creatures live in the mud or sand of marine environments, hence the name. The dragon part, though, is almost ironic since mud dragons barely reach 1 mm in length. In case of the goat mud dragon, the body measures only about 400 µm with a retracted introvert.
The introvert is basically a proboscis that can be everted through the mouth and is covered by small teeth arranged in concentric circles. Although a similar structure, also called introvert, is found in peanut worms (Spincula), they are not related to mud dragons at all, since peanut worms are annelids and mud dragons are more closely related to nematodes and arthropods. The relationship with arthropods is clear since mud dragons also have a segmented body, which always consists of 11 segments, and a cuticle that is molted as the animal grows, just like in arthropods and nematodes.
The goat mud dragon was described only in 2014 based on specimens colleted around Ishigaki Island, part of the Ryukyu Islands of Japan. The specific epithet, hwiizaa, which means “goat” in an Okinawan dialect and refers to the relatively short terminal spines at the posterior end of the species, which, according to the taxonomists who described it, resemble the horns of a goat.
Like all mud dragons, the goat mud dragon is a dioecious species, i.e., there are males and females. Overall, both sexes are very similar in appearance and are not easily distinguished from each other, but females have shorter accessory terminal spines than males. In most mud dragon species that are closely related to the goat mud dragon, females lack accessory terminal spines entirely.
Little is known about the reproduction of mud dragons in general. They have internal fertilization, which means that the male delivers sperm inside the female’s body. When the eggs are ready to be laid, the females protect them with an envelope of mud and organic material and lay them in the substrate.
The diet of mud dragons consists of detritus or small organisms such as diatoms. The exact diet of the goat mud dragon is currently unknown. Due to the microscopic size of these animals, they are a very neglected animal group. Less than 300 species are currently known but this number is likely way below the total number of species. The sand and mud of the oceans are probably filled with thousands of mud dragon species waiting to be discovered.
Yamasaki, H., & Fujimoto, S. (2014). Two new species in the Echinoderes coulli group (Echinoderidae, Cyclorhagida, Kinorhyncha) from the Ryukyu Islands, Japan. ZooKeys, (382), 27. doi: 10.3897/zookeys.382.6761
Cycads are one of the the earliest diverging lineages among the seed plants (which also include conifers, ginkgo, gnetophytes and flowering plants). They were very abundant during the Mesozoic (the “dinosaur era”) and only few species remain today and, unfortunately, many of them are endagered. This is the case with Microcycas calocoma, the microcycad. This species, the only in the genus Microcycas, occurs only in a small region in western Cuba, in the oldest area of this Caribbean island.
The microcycad has a typical cycad appearance, resembling a palm tree. It can reach up to 10 m in height with its trunk reaching up to 60 cm in diameter. The leaves, with a typical pinnate configuration, grow in a rosette at the top of the trunk, with older leaves falling off and new ones growing above.
The microcycad is listed as critically endangered in the IUCN Red List and only about 600 individuals are left in nature. Although artificial pollination leads to the successful production of seeds, most of the remaining populations show very low seed production or no production at all, which makes them unable to survive by themselves.
As with all cycads, the microcycad is a dioecious species, i.e., there are male and female plants. Although many gymnosperms (i.e., non-flowering seed plants) are pollinized solely by the wind, cycads are often pollinized by insects. Thus, it has been suggested that the inability of most remaining population to reproduce may be the result of the local extinction of pollinators. We don’t know for sure which species pollinate the microcycad, but one candidate is a beetle, Pharaxonotha esperanzae, described in 2005 based on specimens found in male microcycad cones in one of the few populations that show a high reproduction capacity. Considering that beetles of this very same genus are know as pollinators of other cycad species in the Americas and New Zealand, it is very likely that this is, in fact, the right pollinator.
Although it has been suggested that geological changes are one of the main factors responsible for the reduction in the population size of this cycad, human impact is certainly a strong reason as well. This plant is considered very beautiful and there is interest in its use as an ornamental species, so that for many years it was extracted from the wild to be planted in gardens where, due to the lack of pollinators, it cannot reproduce at all. Additionally, domestic and other synthropic species brought by humans to Cuba, especially pigs and rats, end up eating the seeds in the wild, decreasing even more the ability of the microcycad to continue to exist.
Since 1989, the microcycad is considered a National Treasure by the Cuban government and its extraction from the wild is completely forbidden. Let’s hope that, after all those years depleting this rare species, humans can find a way to save it from extinction.
Chavez, R., & Genaro, J. A. (2005). A new species of Pharaxonotha (Coleoptera: Erotylidae), probable pollinator of the endangered Cuban cycad, Microcycas calocoma (Zamiaceae). Insecta Mundi, 70.
Pinares, A., Gonzalez-Astorga, J., Vovides, A. P., Lazcano, J., & Vendrame, W. A. (2009). Genetic diversity of the endangered endemic Microcycas calocoma (Miq.) A. DC (Zamiaceae, Cycadales): Implications for conservation. Biochemical Systematics and Ecology, 37(4), 385-394.
Vovides, A. P., Ogata, N., Sosa, V., & Peña-García, E. (1997). Pollination of endangered Cuban cycad Microcycas calocoma (Miq.) A. DC. Botanical Journal of the Linnean Society, 125(3), 201-210.
It’s been a long time since we had a protist here for the last time, so it is more than time for them to return. Since last week we saw the cosmopolitan polychaete Capitella capitata, the common capitella, I though it would be interesting to bring one of its parasites today. Its name is Ancora sagittata, which I decided to call the arrow anchor.
The arrow anchor is a gregarine, a group of early branching apicomplexans. Apicomplexans are unicellular parasites that include some human parasites as well, such as the ones that causa malaria and toxoplasmosis. All gregarines parasite invertebrates, many of which are marine. Apicomplexans evolved, after all, from marine algae and are closely related to dinoflagellates.
Different from other apicomplexans, gregarines have only one host during their life and, in the case of the arrow anchor, this host are polychaete worms of the genus Capitella. The trophozoite, i.e., the active and feeding stage, of the arrow anchor lives attached to the surface of the gut of capitellas. Its shape resembles an anchor, hence the genus name Ancora. The anterior end of the cell is round and the posterior end is very narrow, ending in a point. There are also two lateral projections that are turned backward and form pointed ends.
For sexual reproduction, two trophozoites contact each other, remaining side by side, and turn into two gamonts, another type of cell. A wall forms around the two gamonts, creating a gametocyst, and both gamonts start to divide indo hundreds of gametes. Still inside the gametocyst, the gametes start to fuse and form zygotes, which in turn become surrounded by another wall, turning into oocysts. Within the oocysts, the zygotes undergo meiosis and form many sporozoites, the spore stage.
Filled with sporozoites, the gametocysts are released in the host’s feces and reach the environment. When they are ingested by a new host, the gametocysts hatch, releasing sporozoites, which infect the gut cells of the new host and turn into trophozoites, restarting the cycle.
It is very likely that almost all capitellas in the world are infected by arrow anchors or other anchor species, and sometimes more than 100 individuais infect a single worm. Their presence does not cause much problems to the host’s fitness and the same is true for many other gregarine species.
As a result of such a “mild” parasitism, gregarines are not economically important parasites for humans and do not receive all the attention from researchers that they deserve.
Simdyanov, T. G., Guillou, L., Diakin, A. Y., Mikhailov, K. V., Schrével, J., & Aleoshin, V. V. (2017). A new view on the morphology and phylogeny of eugregarines suggested by the evidence from the gregarine Ancora sagittata (Leuckart, 1860) Labbé, 1899 (Apicomplexa: Eugregarinida). PeerJ, 5, e3354.