After almost four months I’m back with a new Friday Fellow! It’s been some busy times and I had little to no time left to dedicate to the blog, but I always come back!
Anyway, today’s fellow is a beautiful but also nightmarish shrub that you may know, at least in tropical regions of the world. Its scientific name is Lantana camara, known in English as the common lantana.
Forming sort of a mix between a shrub and a vine, the common lantana can grow up to 2 m in height if standing alone and up to 6 m if climbing through another plant. The leaves are broad, ovate, somehow rough and have a strong scent when crushed.
The flowers are tubular, with four petals, and arranged in clusters. They can have a great variety of colors, including white, yellow, orange, red and pink. The outer flowers in the cluster usually open first and are reddish than the ones in the middle, not only because of their location but because of their age because, after being pollinated, the flowers change color to let pollinators know that they should not waste their time on them anymore and should look for younger flowers instead. This is the same that happens in the common lungwort, which was presented here about half a year ago.
Native to Central and South America, the common lantana has become a popular ornamental plant due to the beauty of its flowers. As a result, it was taken to many other countries and became an invasive species in Florida, Hawaii, Australia, India and tropical Africa. In these areas, it is often described as a noxious weed, and it has even been called one of the worst weeds in recorded history. The main negative effects caused by its introduction outside its native range are that it can be toxic to some animals and releases allelopathic chemicals, which reduce the growth of other plants around it. In Australia, India and South Africa, the common lantana was introduced about two centuries ago and, despite aggressive measures by the governments of these three countries to eradicate it, it continued to spread more and more and currently covers about 2 million hectares in South Africa, 5 million in Australia and 13 million in India, a real nightmare for the local ecosystems.
It looks like fighting against this species is a lost battle all around the world and new strategies dealing with adapting to its presence are necessary. If we can’t beat it, let’s join it.
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Bhagwat, S. A., Breman, E., Thekaekara, T., Thornton, T. F., & Willis, K. J. (2012). A battle lost? Report on two centuries of invasion and management of Lantana camara L. in Australia, India and South Africa. PLoS One, 7(3), e32407. https://doi.org/10.1371/journal.pone.0032407
We are well aware of the drastic effects that the increase in the planet’s mean temperature is having and will have on ecosystems. The acidity of the oceans is increasing and causing problems for species with skeletons of calcium carbonate. The melting of polar ice caps destroys the habitat of polar species and raises the ocean levels, flooding lowland areas and destroying even more ecosystems. But these problems concern mainly species that live in the oceans or on the surface of continents.
Caves are underground ecosystems that harbor an astonishing diversity, including many unique lineages that have been extinct on the surface long ago. Since many caves are small and not directly connected to other caves, species in these habitats are also highly endemic. It is not uncommon to find species living in a single cave, with a very small population. I already presented some cases like this before regarding planarians.
But today we will talk about another cave dude, Proasellus lusitanicus, an aquatic isopod measuring up to 8 mm in length that is endemic to the Estremenho karst massif in Portugal. Lacking eyes and pigmentation, this tiny isopod is completely adapted to life in the caves, and the water in which it lives has a relatively constant temperature of about 17 °C year round. However, the increase in mean global temperature on the surface of the planet can cause an increase in the water temperature inside caves as well.
To understand how P. lusitanicus would cope with an increase in water temperature, researchers Tiziana di Lorenzo and Ana Sofia Reboleira took some specimens to the lab and monitored their response to temperatures between 17 and 22.5 °C, including oxygen consumption. The results were not good. Our tiny isopods show a drastic decrease in respiration with a temperature increase of only a few degrees. At 22.5 °C, they consumed 75% less oxygen than at 17 °C. In fact, 25% of the specimens died when the water temperature increased by only 2.5 °C.
Caves usually have very stable conditions, with little variation in light, temperature, and humidity across the year. As a result, many species, like P. lusitanicus, lose their ability to tolerate a wide range of conditions. If the water temperature in the Estremenho karst massif rises only a few degrees due to climate change, this tiny isopod will likely go extinct. But it will not be the only one. Many, if not most, cave species are similarly sensitive to changes and may have the same tragic end.
Now a place flourishing in amazing species, caves can end up as barren land very soon due to the human inability to care for the planet.
Some species are so peculiar and cute that they look like real-life Pokémon (well, at least what Pokémon used to look like back in the first generations). One of those species is Berthella martensi, the colorful sidegill slug.
Inhabiting the Indo-Pacific, from the intertidal zone up to a depth of about 25 m, the colorful sidegill slug measures about 5 to 6 cm in length as an adult and is often found in shallow lagoons in coral reefs. It is a pleurobranch, a group of sea slugs with an external gill located on the right side of the body, in contrast to the more famous nudibranchs, which have it on the back.
The colorful sidegill slug has a prominent mantle that extends in the form of large lobes covering its body, including its gill. These lobes can be autotomized when the animal feels threatened so that it can escape and leave the predator behind with a small snack to get distracted. But the colorful sidegill slug is a predator itself, feeding on sponges and, according to some sources, also ascidians.
But certainly one of the most remarkable features of the colorful sidegill slug is the variety of different color patterns that the species can present. It can be light cream, almost white, or dark purple, almost black, with many colors in between, such as yellow, orange, red, or purple-gray. Besides the background color, there are often several spots that are of a lighter color in dark-colored animals and of a darker color in light-colored ones. Specimens with a light background color can also have a dark margin on the mantle lobes, usually with the same color as the spots, although this is not always present. In dark-colored ones, the margin has always the same color as the background.
Despite its beauty and cuteness, the colorful sidegill slug is one more species whose ecology is almost completely unknown to us. Even though it has a charismatic look, no one cared to get to know it better until now.
The world is filled with bacteria. Trillions, quadrillions, quintillions of them all around us. But while most of them are harmless or even beneficial to us, others are really evil.
Currently, one of the most dangerous bacteria for humans is called Pseudomonas aeruginosa, which I decided to nickname the green-pus bacterium and you will soon find out why. With a typical rod shape as many bacteria, its cells measure about 1.5 to 3 µm in length and 0.5 to 0.8 µm in width.
Find all around the world, the green-pus bacterium is one of the most generalist species that we have ever discovered. It often lives in oxygen-rich environments, but can also survive in anaerobic places. Provided that the environment has some moisture, it can thrive anywhere, including soil, water, on the surface of animals, plants, and fungi, and on the surface of human-made objects.
The green-pus bacterium feeds on almost anything organic, including living tissue and even hydrocarbons. It has been used, for example, to clean soil and water after oil spills by eating away the oil.
Although not exactly a parasitic species, the opportunistic and generalist habits of the green-pus bacterium make it a potential pathogenic species for humans and many other organisms. If it has the chance to feed on live tissue, it will. And this is not as difficult to occur, as this species can be found living on our skin as part of our microbiota. And how wouldn’t it be there, right? As I said, it thrives everywhere.
Nevertheless, this species is mostly harmless in normal conditions for healthy individuals. It is especially dangerous to immunocompromised individuals or other seriously injured ones. It is one of the most common species to spread and cause hospital-acquired infections. Carried through the air, it can infect the respiratory tract of immunocompromised people and cause pneumonia. Similarly, it can penetrate the urinary tract through infected catheters and cause urinary infections or, also through catheters, it can end up in the bloodstream. Another important route to infect humans is through severe skin burns, through which it can reach the inner tissues and spread, eating the infected individual alive.
Infections by the green-pus bacterium produce, as you may have guessed, a characteristic green pus. When cultivated in the laboratory, the cultures also show a blue-green color, hence the epithet aeruginosa, which in Latin means verdigris-colored. This color is caused by two metabolites produced by the green-pus bacterium named pyocyanin (with a blue color) and pyoverdine (with a green color).
One of the most frightening facts about the green-pus bacterium is that it is resistant to most antibiotics, most of which is due to natural resistance, although it also easily acquires new resistances by natural selection after being exposed to them during antibiotic treatments. This makes it very difficult to fight an infection caused by this species, and an infected person can easily die. As a result, the green-pus bacterium is also one of the most studied bacteria in the world and it stimulates research for the development of new methods to fight against bacterial infections that go beyond the use of antibiotics.
So take care! This little fellow is all around us and, although harmless most of the time, it will not hesitate to infect you if a good opportunity arises.
Lepidopterans are among the most beloved invertebrates among the general public, especially because of the beauty of either the adult or the larval forms, or sometimes even the pupa! Hawkmoths are among those groups that often call people’s attention. They make up the family Sphingidae, and the adults have a peculiar and easily recognizable shape, but their caterpillars are most remarkable.
The Elegant Hawkmoth, Eupanacra elegantulus, is a species found in Southeast Asia. The adults have a brownish color that is not that different from an average hawkmoth. The caterpillars, on the other hand, are very interesting. They feed on plants of the family Araceae, including the genera Aglaonema, Alocasia, Dieffenbachia, Monstera and Syngonium, many of which are highly toxic.
They live on the underside of the leaves on which they feed and start their lives as small, almost plain green caterpillars, with a small straight spine near the posterior end. At their last instars, they show a curious pattern. The spine at the posterior end becomes hooked, and a little behind the three pairs of true legs the dorsum shows a large eyespot on each side. A black line forming a more or less oval shape connects the eyespots on both sides, and the area that this line surrounds shows a pattern that resembles reptile scales.
The body at this stage can be either green or brown, and the caterpillar kind of resembles a snake, when its head is withdrawn, or a crocodile, when it is extended forward.
When they pupate, they attach themselves under a leaf surrounded by a very loose cocoon of silk with some debris.
Despite being a species with a very interesting pattern that mimics snakes or crocodiles, which catches the attention of many people, there are no studies at all focused on this species. Nowadays, citizen science is becoming an important source of knowledge and I think this species would benefit a lot of projects that include the participation of the community.
Lichens form an astonishingly diverse group of algae-associated fungi that are found in all sorts of places over the world. One of the most easily recognizable genera is Usnea, whose species are commonly known as beard lichen. One of the most widespread species across the globe is Usnea hirta, the bristly beard lichen.
Like all species of Usnea, the bristly beard lichen is a fruticose lichen, which means it grows in the shape of a small leafless shrub or coral on the surface of trees. It has a grayish-green or greenish-gray color, and its “branches” are very flexible but not as long as in other species that look more like a beard. It prefers to grow on acid bark, especially branches of conifers such as Pinus, and is not that common in deciduous trees, at least in temperate regions. It likes open sites where it can receive lots of sunlight.
With worldwide distribution, the bristly beard lichen is a relatively heterogeneous species, which led to many problems in its classification, as many regional forms were described as separate species and later revealed to be the same Usnea hirta.
Like many lichens, the bristly beard lichen can reproduce both sexually and asexually. Sexual reproduction occurs through spore production in apothecia (singular apothecium), cup-shaped structures. When the spores are released in the environment and germinate, they need to find a compatible alga to start a new association or the fungus will not survive. Thus, sexual reproduction is very difficult and asexual reproduction is the most efficient strategy. It consists of forming soralia (singular soralium), small “warts” that grow attached to the branches of the lichen. The soralia are groups of sorecia (singular sorecium), which are small units formed by a piece of alga surrounded by fungal hyphae. As both components of the association are already present, a sorecium can germinate whenever it lands on a suitable surface.
The bristly beard lichen is very sensitive to air pollution, especially to sulfur dioxide (SO2) and nitrogen compounds. It has also shown the ability to bioaccumulate heavy metals in its tissues. As a result, more recent studies are trying to turn it into a model species for bio-monitoring of air pollution, especially in North America.
Thus, if you find yourself surrounded by trees covered with lots and lots of bristly beard lichens, it is likely that the air where you live is not that bad, at least considering sulfur and nitrogen compounds.
Shrestha, G., Petersen, S. L., & CLAIR, L. L. S. (2012). Predicting the distribution of the air pollution sensitive lichen species Usnea hirta. The Lichenologist, 44(4), 511-521. https://doi.org/10.1017/S0024282912000060
One of the most enigmatic animal phyla is Chaetognatha, which are commonly known as arrow worms. Less than 200 species are known, but some species are very abundant, so it is not that difficult to find one if you look at the right place. One particularly common species is Spadella cephaloptera, which I decided to call the shore-dwelling swordworm.
All arrowworms are very small, measuring up to 10 or 12 cm in the largest specimens, but the shore-dwelling swordworm is much smaller, with only about 5 mm in length. They are marine creatures and most species are planktonic, but the shore-dwelling swordworm is an exception that lives in shallow waters near the shore, usually attached to the surface of seaweed or marine angiosperms around Europe.
The body of the shore-dwelling swordworm is kind of dart-shaped, transparent, and consists of a rounded head, an elongate trunk and a short tail. The second half of the trunk and the tail are surrounded by a flat expansion that functions like a fin. Like in all arrowworms, the shore-dwelling swordworm has one set of hooked, grasping spines on each side of the head, on their “cheeks”. They use these spines to capture their prey, which consist mainly of small crustaceans living in the same habitat.
The shore-dwelling swordworm is a hermaphrodite like all arrowworms. The female reproductive apparatus lies in the second half of the trunk and the male one in the tail. Mating does not include reciprocal insemination like in other hermaphrodites. One of the two individuals, which has its seminal vesicles full, approaches another, which has its seminal receptacle empty, and deposits a mass of sperm at the entrance of the vagina of the second. The cilia of the vagina start to become very active and the spermatozoa start to swim across the cilia to enter the vagina until they reach the seminal receptacle.
Both individuals remain in contact, with one facing the tail of the other, until the seminal receptacle of the receiving one is full or until they are disturbed. If some sperm mass still remains outside of the vagina when they separate, the receiving one eats what has been left out. After the eggs are fertilized, they still remain some hours inside the mother until they are laid. About 12 to 16 eggs are laid at intervals of eight to ten days. The eggs remain attached to the substrate and, in about 48 hours, they hatch into small versions of the adults, without a larval phase.
Although almost invisible and often ignored, the shore-dwelling swordworm is an important predator in this specific shore ecosystem which is, of course, connected to the large marine ecosystem and, consequently, to the whole biosphere. But how much do they affect the dynamics of their ecosystem? This is something that still needs to be investigated.
As a kid and teen, I was fascinated by the lifeforms that I could find in our backyard, including many simple photosynthetic organisms such as cyanobacteria (my lovely Nostoc, already presented here a long time ago), mosses and, of course, green algae. Green filamentous algae used to grow in large quantities in ponds and puddles forming widespread slimy and hairy “patches”. Most of them were, I suppose, part of the genus Spirogyra.
Widespread across the world, especially in temperate climates, the genus Spirogyra contains hundreds of species. They are all very similar and, from what I can tell, very hard to be determined to the species level. It’s been quite some time since I wanted to bring a species of Spirogyra here, but most images available online are identified only to the genus level, and studies that go to the species level lack photographs of them. But after some time trying to find a good species, I ended up choosing one named Spirogyra neglecta, which would translate as the neglected spirogyra, a name that somehow describes the overall status of the genus, I think, at least regarding material that is easily available to non-spirogyrologists.
Anyway, the neglected spirogyra, as all species of Spirogyra, belongs to the order Zygnematales, which consists of filamentous algae. But what does filamentous algae mean? It means that they exist as a colony of cells attached to each other in very long strings, or filaments, that can grow longer and longer as the cells continue to divide. In the case of Spirogyra, the most striking feature is their chloroplast, which has a spiral shape, hence the name of the genus. The number of chloroplasts in each cell varies from species to species. Some have only one, while others can have as many as eight, or perhaps even more. In the case of the neglected spirogyra, the number is usually two or three.
Found across the Holarctic region (North America, Europe, and northern Asia), the neglected spirogyra likes to grow in clear and eutrophic (nutrient-rich) water. It often grows completely submerged, but on sunny days the increased photosynthesis makes oxygen bubbles appear among the filaments and the whole “mat” can end up floating to the surface.
The most common form of reproduction among species of Spirogyra is through simple cellular division. The typical cells that form the colonies are haploid, having only one copy of each chromosome. When the environmental conditions are not good for them to survive or grow, sexual reproduction can occur through a process called conjugation. In this process, two cells, usually from different filaments that lie side by side, connect to each other through a conjugation tube. The content of one of the cells (considered the male) migrates into the other cell (considered the female) and their nuclei fuse, thus originating an ovoid zygote. The zygote becomes surrounded by a thick wall, forming the so-called zygospore, which can withstand harsh conditions such as drought or lack of nutrients for several months. During this time, the diploid nucleus of the zygospore undergoes meiosis, forming four haploid nuclei of which only one survives. When the environmental conditions are adequate, the zygospore germinates into a new Spirogyra cell, which will grow into a new filament as it reproduces by fission.
Species of the genus Spirogyra are edible, and the neglected spirogyra is no different. These algae are a common ingredient in northern Thai cuisine, where they are eaten especially raw as salad. Despite being a cheap food, the neglected spirogyra is rich in nutrients and has antioxidant properties. Extracts from this alga have shown anti-inflammatory and anticancer activities, as well as the ability to stimulate the immune system.
Have you ever thought of making a salad from that green filamentous mat that grows in ponds around you?
Duangjai, A., Limpeanchob, N., Trisat, K., & Amornlerdpison, D. (2016). Spirogyra neglecta inhibits the absorption and synthesis of cholesterol in vitro. Integrative Medicine Research, 5(4), 301-308. https://doi.org/10.1016/j.imr.2016.08.004
Mesbahzadeh, B., Rajaei, S. A., Tarahomi, P., Seyedinia, S. A., Rahmani, M., Rezamohamadi, F., … & Moradi-Kor, N. (2018). Beneficial effects of Spirogyra Neglecta Extract on antioxidant and anti-inflammatory factors in streptozotocin-induced diabetic rats. Biomolecular Concepts, 9(1), 184-189. https://doi.org/10.1515/bmc-2018-0015
Ontawong, A., Saowakon, N., Vivithanaporn, P., Pongchaidecha, A., Lailerd, N., Amornlerdpison, D., … & Srimaroeng, C. (2013). Antioxidant and renoprotective effects of Spirogyra neglecta (Hassall) Kützing extract in experimental type 2 diabetic rats. BioMed Research International, 2013. https://doi.org/10.1155/2013/820786
Schagerl, M., & Zwirn, M. (2015). A brief introduction to the morphological species concept of Spirogyra and emanating problems. Algological studies, 67-86. 10.1127/algol_stud/2015/0231
Surayot, U., Wang, J., Lee, J. H., Kanongnuch, C., Peerapornpisal, Y., & You, S. (2015). Characterization and immunomodulatory activities of polysaccharides from Spirogyra neglecta (Hassall) Kützing. Bioscience, Biotechnology, and Biochemistry, 79(10), 1644-1653. https://doi.org/10.1080/09168451.2015.1043119
Thumvijit, T., Taya, S., Punvittayagul, C., Peerapornpisal, Y., & Wongpoomchai, R. (2014). Cancer chemopreventive effect of Spirogyra neglecta (Hassall) Kützing on diethylnitrosamine-induced hepatocarcinogenesis in rats. Asian Pacific Journal of Cancer Prevention, 15(4), 1611-1616. https://doi.org/10.7314/APJCP.2014.15.4.1611
There are endless forms of beauty among the small creatures that we often do not see around us. Mites, which are so ubiquitous, contain several neglected beauties. One of them is today’s fellow, Eatoniana plumipes, known as the Mediterranean Plumefoot Mite.
Adults of the Mediterranean Plumefoot Mite are considerably large for a mite, measuring a few millimeters in length, often more than 1 cm when the legs are considered. They are reddish-brown, lighter at the legs and other appendices, and their hind legs are much longer than the others and have a tuft of long black hair that makes them look like plumes, hence the name plumefoot mite. As the common name also suggest, this species is found around the Mediterranean, including southern Europe, northern Africa, Turkey and the Middle East.
Despite being a large and rather beautiful mite, very little is known about the life history of the Mediterranean Plumefoot Mite. It belongs to a group of mites that are predators as adults but parasites as larvae. The larvae hatch from red eggs laid by the female in the environment and are, of course, much smaller than the adults. They also have only three pairs of legs, and not four like the adults, and lack the characteristic plumes seen in the adults.
Little to nothing is known about the feeding habits of this species. Grasshoppers are among the identified hosts of the larvae, but it is likely that other arthropods are parasitized as well. The larvae attach to the legs of the hosts and feed there, sucking their hemolymph (the “blood” of arthropods). I could not find any information about which species serve as prey for the adults.
Even though we know almost nothing about the ecology of the Mediterranean plumefoot mite, we can still appreciate its beauty, and it certainly plays a fundamental role in its ecosystem.
If you live around the Mediterranean, have you ever seen one of them? Let us know!
Mąkol, J., & Sevsay, S. (2015). Abalakeus Southcott, 1994 is a junior synonym of “plume-footed” Eatoniana Cambridge, 1898 (Trombidiformes, Erythraeidae)-evidence from experimental rearing. Zootaxa, 3918(1), 92-112. https://doi.org/10.11646/zootaxa.3918.1.4
Noei, J., & Rabieh, M. M. (2019). New data on Nothrotrombidium, Southcottella and Eatoniana larvae (Acari: Trombellidae, Neothrombiidae, Erythraeidae) from Iran. Persian Journal of Acarology, 8(3). https://doi.org/10.22073/pja.v8i3.46776
Most flatworms known to date are parasites, and it is likely that these are, indeed, the majority of the phylum. Nevertheless, the diversity of free-living flatworms is certainly underestimated. This is especially noticeable when we talk about today’s fellow, Gyratrix hermaphroditus, a tiny flatworm that I decided to call the hermaphrodite turner in English.
Measuring about 1 to 2 mm in length, the hermaphrodite turner is a cute little pal. It is shaped like an elongate drop, rounded at the posterior end and kind of pointed at the anterior end. There are two small black eyes that lie a little behind the anterior end, making it look like it has an elongate and movable snout. It kind of looks like a microscopic version of a seal.
Because the body of the hermaphrodite turner is transparent, you can see its internal organs very easily. Between the eyes and the anterior tip, we can notice a sort of transparent cylindrical structure, which is its proboscis, used to capture prey. When the intestine is full of food, it can also be noticed.
The hermaphrodite turner is a curious animal because it is not only found all over the world, on all continents, but also in both freshwater and marine environments. In fact, it is not a single species, but a complex of very similar species that have been considered, or treated like, a single species for decades. Recent molecular studies, however, made it clear that the hermaphrodite turner is not one but many different species. Although instances of species complexes considered a single species is common among microscopic organisms, the hermaphrodite turner is a special case in which, from what we discovered until now, the complex includes a really huge number of species, probably hundreds of them.
As the name of the hermaphrodite turner implies, it is a hermaphrodite like most flatworms. Near the posterior end of its body, we can see a straight needle-like structure, the stylet. This is part of the male copulatory apparatus, forming kind of a hard needle-like penis, which is used to penetrate the body of other individuals to inseminate them. Sometimes we can also see individuals with unlaid eggs inside them. These appear as oval-shaped brownish structures. When the eggs are laid, they are attached to the substrate by a small stalk to prevent them from being carried away by the water.
Despite the worldwide distribution of this species complex, we know almost nothing about the behavior and ecology of these organisms. They feed on smaller animals and protists that share the same environment as them. They often capture prey using their proboscis, but they can also use their stylet to stab. Afterward, they place their mouth over the wound and start sucking the prey’s contents. The mouth is on the ventral side at about the middle of the body as in most flatworms.
Let’s hope that our fellow zoologists that work with these tiny flatworms start splitting this complex into the actual species, as it deserves.
Tessens, B., Gijbels, M., & Artois, T. (2009). MATING AND FEEDING BEHAVIOUR OF THE EURYHALINE COSMOPOLITAN FLATWORM GYRATRIX HERMAPHRODITUS. Belgium, 27 November 2009: VLIZ Special Publication, 43. Vlaams Instituut voor de Zee (VLIZ): Oostende, Belgium. xiii+ 221 pp.
Tessens, B., Monnens, M., Backeljau, T., Jordaens, K., Van Steenkiste, N., Breman, F. C., … & Artois, T. (2021). Is ‘everything everywhere’? Unprecedented cryptic diversity in the cosmopolitan flatworm Gyratrix hermaphroditus. Zoologica Scripta, 50(6), 837-851. https://doi.org/10.1111/zsc.12507