Friday Fellow: Sand-Dollar Pea Crab

by Piter Kehoma Boll

Last week I presented the lovely five-slotted sand dollar, a very common echinoderm along the Atlantic Coast of the Americas. But as we all know, species rarely live by themselves. All kinds of association exist between organism, and today our species is one that lives closely associated with the five-slotted sand dollar, the sand-dollar pea crab, Dissodactylus mellitae.

The sand-dollar pea crab is, like its name suggests, a crab. A very very small crab indeed. Adult males reach up to 3.5 mm in size and females do not grow larger than 4.5 mm. They have a light-yellow to white color, sometimes with a complex pattern of darker marks on the dorsum.

The tiny sand-dollar pea crab. Credits to Naturalist Biodiversity Center.

The natural habitat of the sand-dollar pea crab is the surface of sand dollars, especially the five-slotted sand dollar. As they are very small, they live very comfortably among the hairs and spines of their host, most commonly on their ventral side, protected from light and possible predators.

For some time it was unknown whether the relationship between both species was that of commensalism, where the crab only eats together with the sand dollar, or of parasitism, where the crabs steals food from the sand dollar or feeds on the sand dollar itself. Analysis of the stomach content of the crabs revealed that up to 80% of its diet consists of tissues of the sand dollar, so that their relationship is most likely parasitic. In fact, it has been shown that the presence of the crabs reduces the number of eggs that female sand dollars produce.

Sand-dollar pea crab on its host. Credits to Naturalist Biodiversity Center.*

The maximum number of crabs observed on a single sand dollar was 10, but this number is highly dependent on the crab’s life stage. In summer, juveniles often prefer to live together, sharing the same host, but as they grow they disperse and prefer a solitary life, not sharing their host with others of the same species. When they are sexually mature, though, they often share the host with another crab of the opposite sex, thus facilitating reproduction. However, males seem to be much more common in the population, so males pairing with other males are more common than males pairing with females.

Reproduction seems to occur around late summer and fall along the coast of North America, after which the number of adult crabs starts to decrease. Juveniles start to appear in late spring, eagerly looking for sand dollars to colonize.

In the sea, different species associate even more frequently than on land. And we know that wherever there is life, there will be another life to parasitize it.

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References:

George, S. B., & Boone, S. (2003). The ectosymbiont crab Dissodactylus mellitae–sand dollar Mellita isometra relationship. Journal of Experimental Marine Biology and Ecology, 294(2), 235-255. https://doi.org/10.1016/S0022-0981(03)00271-5

Telford, M. (1982). Echinoderm spine structure, feeding and host relationships of four species of Dissodactylus (Brachyura: Pinnotheridae). Bulletin of Marine Science, 32(2), 584-594. https://www.ingentaconnect.com/content/umrsmas/bullmar/1982/00000032/00000002/art00017

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* This work is licensed under a Creative Commons Attribution-NonCommercial-Share Alike 3.0 Unported License.

Friday Fellow: Five-Slotted Sand Dollar

by Piter Kehoma Boll

If you ever walked along the beaches of the Atlantic Coast from the United States to Brazil, you probably found the skeletons of today’s fellow lying on the sand. Its scientific name is Mellita quinquiesperforata, known in English as the five-slotted sand dollar.

A washed ashore skeleton of the five-slotted sand dollar. Photo by Maria Fernanda Molina G.**

The five-slotted sand dollar is an echinoderm of the class Echinoidea and, therefore, closely related to sea urchins. Like all sand dollars, it has a flattened body with a secondary bilateral symmetry that evolved from the original radial symmetry of echinoderms (which itself is a secondary development of the original bilateral symmetry of bilaterian animals). Their body is flat, almost circular, but wider than long, reaching up to 12 cm in width. Live animals have a kind of velvet-like texture formed by the spines and hairs covering their skin. A star-like mark can be seen on their backs, which is formed by five rows of pores through which podia, responsible for gas exchange, come out. One of the arms of the star is directed to the front of the animal. The mouth is located at the center of the ventral side and the anus is at the posterior end of the body.

Five-slotted sand dollars are adorable. Photo by Andrea Caballero.*

The name of the five-slotted sand dollar comes from the fact that its body has five elongate perforations, four of which are continuous with the four lateral rows of pores and the fifth one is behind, between the two posterior rows. These openings help the sand dollar move more easily through the sand by allowing sand to pass through their bodies and they can also help drag food toward the mouth. At the same time, the perforations embed them better in the sand, reducing their chances of being swept away by the waves.

Ventral side of a live specimen. Photo by Andrew J. Crawford.

The five-slotted sand dollar likes substrates made of fine sand, being unable to burrow into gravel or coarse sand. Muddy substrate is aversive to them but they will burrow into it if there is no choice.

Dorsal side. Photo by iNaturalist user tropical_dragonfly.*

The five-slotted sand dollar is a deposit feeder, feeding on small organisms from the sand, especially bacteria and microscopic eukaryotes, which it removes from the small clay particles that it ingests. Its feeding behavior and general displacement through the sediment helps increase oxygenation of the substrate. Thus, its presence has a large impact on the community of organisms able to live on a beach.

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References:

Alexander, D. E., & Ghiold, J. (1980). The functional significance of the lunules in the sand dollar, Mellita quinquiesperforata. The Biological Bulletin, 159(3), 561-570. https://doi.org/10.2307/1540822

Bell, B. M., & Frey, R. W. (1969). Observations on ecology and the feeding and burrowing mechanisms of Mellita quinquiesperforata (Leske). Journal of Paleontology, 553-560. https://www.jstor.org/stable/1302333

Findlay, R. H., & White, D. C. (1983). The effects of feeding by the sand dollar Mellita quinquiesperforata (Leske) on the benthic microbial community. Journal of Experimental Marine Biology and Ecology, 72(1), 25-41. https://doi.org/10.1016/0022-0981(83)90017-5

Weihe, S. C., & Gray, I. E. (1968). Observations on the biology of the sand dollar Mellita quinquiesperforata (Leske). Journal of the Elisha Mitchell Scientific Society, 315-327. https://www.jstor.org/stable/24333312

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* This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

** This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

Friday Fellow: Coriander

by Piter Kehoma Boll

Today I decided to present again a popular species and a very controversial one regarding personal taste, Coriandrum sativum, known in English as coriander or cilantro. Although it is a well-known spice, there is always some things that we don’t know about this plant.

Coriander plants showing the leaves of different shape at the base and at the top. Photo by Wikimedia user Salicyna.*

Coriander is native from Western Asia and Southern Europe. It is a herb that grows up to 50 cm in height and has leaves of variable shape, broader and lobed at the base of the plant and slender and feathery at the top, around the flowers. The flowers have white or very pale pink petals and are arranged in umbels, the typical inflorescence of plants in the family Apiaceae, which is also known as Umbelliferae for obvious reasons. The flowers are asymmetrical, with the petals that point away from the center of the inflorescence being much longer that the ones pointing toward the center. The fruis are schizocarps, a type of dry fruit that splits into smaller parts called mericarps.

Coriander inflorescences. Notice the asymmetrical flowers. Photo by H. Zell.**

Coriander is used as a food by humans since pre-historical times. The oldest evidence comes from desiccated mericarps found in the Nahal Hemar cave in Palestine and dated back to the Pre-Pottery Neolithic B (around 8800–6500 BC). Half a liter of coriander mericarps were also found in the tomb of Tutankhamen, suggesting that this plant was cultivated in Egypt, since it is not native from that region.

Humans use the whole plants as food, but the most valued parts are the fresh leaves and dried seeds. Some people enjoy the taste of coriander leaves, while others hate it. Genetic and populational studies have shown that these differences in preferences have likely a genetic origin, with the two groups having different senses of smell, i.e., they are more sensitive to different chemicals found in the leaves.

Coriander fruits. Photo by Wikimedia user Bierfaß.**

Coriander aqueous extracts and essential oil showed to have many important properties, including analgesic, anthelmintic, antibacterial, anti-cancer, anti-convulsant, anti-fungal, anti-inflamatory, antioxidant and anxiolytic activities, among many others, so that the plant has the potential to lead to the development of many new medications.

What about you? Are you a coriander lover or a coriander hater?

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References:

Laribi, B., Kouki, K., M’Hamdi, M., & Bettaieb, T. (2015). Coriander (Coriandrum sativum L.) and its bioactive constituents. Fitoterapia, 103, 9-26.

Wikipedia. Coriander. Available at <https://en.wikipedia.org/wiki/Coriander>. Access on 20 May 2021.

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* This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

** This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.

Friday Fellow: Northern Stargazer

by Piter Kehoma Boll

Look at this picture:

Doesn’t it look like something coming directly from your nightmares? Well, it certainly is a real nightmare from some fish. Named Astroscopus guttatus, its common name is the northern stargazer.

The name stargazer comes from the fact that this species and other stargazers (which make up the family Uranoscopidae) have their eyes and mouth facing up, so that they seem to be always looking at the sky above. The northern stargazer measures up to 56 cm in length and has a brownish color with white spots on its head and back, although most of its body is almost never seen. It is found along the Atlantic Coast of the United States and is a benthic species that buries itself in the sand, letting only its face out.

An unburied northern stargazer. Photo by iNaturalist user craigjhowe.*

To bury itself, the northern stargazer swims clumsily until reacher a sandy bottom. It then lies there and starts to throw sand away using its pectoral fins, which makes its head start to think. At the same time it wiggles from side to side, making its anal fin slide down into the sand and slowly burying its posterior half as well. When only the eyes, the mouth and, sometimes, the tip of the tail are left out, it ceases to move and waits. When a fish or invertebrate swims or walks above the face of the stargaze, it can quickly jump and capture that poor creature that now has become its tasty meal.

But the terrible nature of the northern stargazer does not lie only on its nightmarish appearance or its predatory behavior. This fish is also venomous, having two large venomous spines above its pectoral fins, just behind the opercles that cover its gills. More than that, the northern stargazer can also cause electric shocks using an electric organ in the middle of its head, which is formed by modified eye muscles.

When the northern stargazer feels threatened, it can dig much more quickly, throwing sand violently and making water turbid for some time. When sand settles, there is nothing to see, as the fish has buried itself up to 30 cm in the substrate.

Now imagine being a small marine fish having to live your life in fear that a horrendous monster can jump out of the sand at any moment to inject you venom, give you an electric shock and devour you.

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References:

Dahlgren, U. (1927). The life history of the fish Astroscopus (the” Stargazer”). The Scientific Monthly, 24(4), 348-365. https://www.jstor.org/stable/7905

Schwartz, F. J. (2000). Ecology and distribution of three species of stargazers (Pisces: Uranoscopidae) in North Carolina. Journal of the Elisha Mitchell Scientific Society, 153-158. https://www.jstor.org/stable/24335504

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* This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License.

Friday Fellow: Swan Lacrymaria

by Piter Kehoma Boll

Among the heterogeneous group of single-celled eukaryotes often called protists, one group that shows a striking diversity and cell complexity is that of the ciliates. Today I will present one more species in this group. The first one was presented here some years ago.

Named Lacrymaria olor, today’s species lacks a common name, but swan lacrymaria seems to be a good one. Swan here comes from the translation of its specific epithet, olor, but it is very adequate considering the species’ shape. Found in freshwater ponds, it is often near aquatic vegetation or decaying plant matter, where its food also lives.

The main part of the swan lacrymaria’s body is not that different from an average ciliate, measuring about 100 µm in length and having kind of the shape of a teardrop, hence the name of the genus Lacrymaria, from Latin lacryma, tear. But extending from the cell there is a very long “neck”, which makes the whole cell look like some sort of swan with a very very long neck.

Lacrymaria olor, a microscopic swan. Photo by Flickr user Picturepest*.

This neck projection is the most active part of the swan lacrymaria’s cell. While the drop-shaped cell body part remains considerably still and hidden, the neck screens the environment looking for food, which often consists of smaller organisms. The neck can move from one side to the other, move around obstacles and extend up to 2 mm, which is about 20 times the length of the cell. The end of the neck has the oral apparatus, through which food is ingested. A ring of long cilia surround the oral apparatus, beating furiously during the hunting behavior.

Watch this amazing video with this protist in action. Extracted from Coyle et al. (2019).

When a prey is found, the swan lacrymaria quickly captures and engulfs it in less then a second, probably injecting a paralyzing toxin in the process. Once inside the “mouth”, the prey is “swallowed”, being pushed toward the main portion of the cell, which may take several seconds.

The swan lacrymaria’s incredible neck agility seems to be related to its complex cytoskeleton in which, for example, the fibers change their orientation in the neck in relation to the body. It’s amazing to watch such a complex behavior in a single-celled organism.

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References:

Coyle, S. M., Flaum, E. M., Li, H., Krishnamurthy, D., & Prakash, M. (2019). Coupled active systems encode an emergent hunting behavior in the unicellular predator Lacrymaria olor. Current Biology, 29(22), 3838-3850.

Wan, K. Y. (2019). Ciliate Biology: The Graceful Hunt of a Shape-Shifting Predator. Current Biology, 29(22), R1174-R1176.

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* This work is licensed under a Creative Commons Attribution 2.0 Generic License.

Friday Fellow: Azores Bellflower

by Piter Kehoma Boll

Oceanic Islands are a treasure of biodiversity and include many small and endemic species. When we come to the Azores archipelago, we find one of those little treasures in the form of a small shrub, the so-called Azores bellflower. Taxonomically, the species is named Azorina vidalii, being the only species in the genus Azorina. The genera of the family Campanulaceae (bellflowers) are a mess, though, and this may eventually change.

The Azores bellflower grows in all nine islands that make up the Azores. It likes to grow near the coastline, especially in crevices of the coastal rocks or sandy slopes, but it can also colonize human structures, such as roofs and walls. It likes very exposed locations and is very tolerant to the sea breeze. Although this plant is usually a very small woody shrub with about 30 cm in height, it can grow up to 2 m.

Typical look of the plant. Photo by iNaturalist user experience.NATURE.*

Despite being found across the whole archipelago, the Azores Bellflower is considered an endangered species. There are only about a thousand adult specimens in total. One of the reasons for such a small population may be due to the lack of an efficient pollinator. The flowers are light pink or white and have a shape that suggests birds as the most likely pollinators, but there is no native bird species in the archipelago that could do this job. Several insects, including bees, wasps, flies and moths, sometimes visit the flowers and may be the current pollinators, but most probably none of them is very efficient in this job. The combination of all of them seems to be enough to keep the current population relatively stable.

The beautiful flowers of the Azores bellflower. Photo by iNaturalist user mariamadalena.*

When honeybees visit the plants, they are often more interested in the latex that the Azores bellflowers secrets. The bees look for recent wounds on the plants where latex is leaking and collect it, sometimes having difficulty leaving the plant because the latex is so sticky that the bees get partially glued to the plant. It is thought that the latex has antimicrobial properties, protecting the plant from bacterial infections, and the bees most likely explore this resource to use it as a natural antibiotic in their combs, perhaps mixing it with pollen to make propolis.

A plant with more pinkish flowers. Photo by Attila Steiner.*

The current population of the Azores bellflower is stable but very small, which is the main reason why it is considered endangered. To assure its survival in the next decades or centuries (and beyond), it is essential to preserve the rocky shores where they thrive and, of course, the diversity of pollinators, which are doing their best to bring new generations of this small Azorean jewel.

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References:

Haberle, R. C., Dang, A., Lee, T., Peñaflor, C., Cortes-Burns, H., Oestreich, A., … & Jansen, R. K. (2009). Taxonomic and biogeographic implications of a phylogenetic analysis of the Campanulaceae based on three chloroplast genes. Taxon, 58(3), 715-734. https://doi.org/10.1002/tax.583003

Weissmann, J. A., & Schaefer, H. (2015). Honeybees (Apis mellifera) collect latex of Azores bellflowers (Azorina vidalii, Campanulaceae). ARQUIPÉLAGO. Life and Marine Sciences, 32. https://repositorio.uac.pt/handle/10400.3/3906

Weissmann, J. A., & Schaefer, H. (2018). The importance of generalist pollinator complexes for endangered island endemic plants. Arquipélago-Life and Marine Sciences, 35, 23-40. https://repositorio.uac.pt/handle/10400.3/4861

Wikipedia. Azorina. Available at < https://en.wikipedia.org/wiki/Azorina >. Access on 29 April 2021.

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Friday Fellow: Fire-Ant Internal Microsporidium

by Piter Kehoma Boll

Last week we learned about the red imported fire ant and the nuisance that it presents in North America, where it was introduced almost a century ago and has turned into a threat to ecosystems and people. As chemical pesticides are often harmful to species other than the one targeted, more species-specific alternatives are often sought. One of those is biological control, which can also be problematic if incorrectly used.

Today’s species is one of those biological agents that can help control the invasion of the red imported fire ant. Named Kneallhazia solenopsae, which I decided to nickname as the fire-ant internal microsporidium, this species belongs to the division Microsporidia, which are single-celled fungi. I already presented one of them here several years ago, the flounder glugea.

The fire-ant internal microsporidium is known to infect fire ants, including the red imported fire ant. It has a very complex life cycle with several stages that is not completely understood yet.

The most serious infection occurs in queens, in which the life stage known as type 2 dikaryotic spore (Type 2 DK) infects the fat body tissue. This is a stage of the microsporidium in which the cell has two nuclei, hence the name. Other adult ants are also infected similarly. The infection spreads slowly, causing hypertrophy of the fat body tissue and, at advanced infections stages, makes this tissue be completely replaced by masses of spores, preventing the development and reproduction of the queen. However, it takes a long time for the microsporidium to cause such a serious disease. It does not mean that it is doing nothing to make things worse before that, though.

While the fat body tissue of the queen is being slowly consumed by the Type 2 DK spores, many of them turn into another stage, the octospore, so called because it occurs in a vesicle which contains eight of them. These vesicles are relatively large compared to the other stages and are thought to be the infectious stage. An injured or dead ant, which is often cannibalized by others, releases the vesicles in the environment. They need to be ingested for infection to occur, but only 4-instar larvae are able to swallow them, because all other larval stages, as well as adults, have a “filter” in their mouth that prevents them ingesting particles larger than 0.8 µm and the vesicles are larger than that.

Several vesicles with octospores and a Type 2 DK spore of the fire-ant internal microsporidium. Photo by David Williams.**

Inside the 4-instar larvae, the vesicles release the octospores, which infect the larvae and fuse, turning into another type of cell with two nuclei, the Type 1 DK spores. Those spores are only found in 4-instar larvae and pupae and are supposed to turn into Type 2 DK spores during the development into adult ants, where they can produce new octospores.

But this is not the only way the microsporidium spreads through the colony. Going back to the queens, the Type 2 DK spores also infect their ovaries and, after the queen is inseminated, they turn into another stage, the so-called megaspore. These megaspores infect the eggs and are incorporated into the embryo and pass directly to the 1-instar larvae, where they develop into Type 1 DK spores as they grow.

So the only way for an ant to become infected is if it receives the parasite directly from the queen in the egg or if it ingests the octospore vesicles as a 4-instar larva? No. And the reason is the fact that ants perform trophallaxis, which is the transfer of food from one individual to the other, i.e., the ants vomit into each other’s mouth. Thus, if an adult ant exchanges food with a 4-instar larva that has released octospores in its gut, it may end up infected as well.

That is quite a complicated life cycle, right? But it seems to be quite well tuned for the microsporidium to be a successulf parasite of fire ants. Is it an efficient biological control though? Well, I would say that it may help slowing down the spread of fire ants, but as its effects causing sterility to the queen take a long time to appear, it will not lead to the removal of the ants in areas they have invaded already.

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References:

Knell, J. D., Allen, G. E., & Hazard, E. I. (1977). Light and electron microscope study of Thelohania solenopsae n. sp.(Microsporida: Protozoa) in the red imported fire ant, Solenopsis invicta. Journal of Invertebrate Pathology, 29(2), 192-200. https://doi.org/10.1016/0022-2011(77)90193-8

Oi, D. H., & Williams, D. F. (2002). Impact of Thelohania solenopsae (Microsporidia: Thelohaniidae) on polygyne colonies of red imported fire ants (Hymenoptera: Formicidae). Journal of Economic Entomology, 95(3), 558-562. https://doi.org/10.1603/0022-0493-95.3.558

Sokolova, Y. Y., & Fuxa, J. R. (2008). Biology and life-cycle of the microsporidium Kneallhazia solenopsae Knell Allan Hazard 1977 gen. n., comb. n., from the fire ant Solenopsis invicta. Parasitology, 135(8), 903.

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** This work is licensed under a Creative Commons Attribution 3.0 Unported License.

Friday Fellow: Red Imported Fire Ant

by Piter Kehoma Boll

While most species presented here have very little available information about their ecology, today’s species is a very well researched organism because it is a worldwide threat. Its current accepted binomial name is Solenopsis invicta and its common name in English is often red imported fire ant. But why?

The red imported fire ant is native from central regions of South America, including western Brazil, northern Argentina, Paraguay, Bolivia and southeastern Peru. The workers range from about 2.5 to 6 mm in length and have a reddish brown or yellowish color, with a darker abdomen. Some colonies may have two castes of workers, a smaller and a larger one, while others have only one.

Mating occurs during the warmer months, when the typical nuptial flight of ants occur. Males die after mating and queens start to build their nest, sometimes alone, sometimes in groups. Thus, colonies can have a single or multiple queens, and in the latter case they may fight for dominance. The nests are built in the ground and the soil that is displaced to excavate the nest is often deposited around the nest entrance, forming a mound of small grains.

A typical mound at the entrance of a nest. Photo by iNaturalist user stanushhn.**

The red imported fire ant is omnivorous and mainly a scavenger, feeding especially on dead animals and sweet liquids such as nectar and honeydew, the sweet substance secreted by some insects. As a predator it may attack other insects, especially dipterans and termites, but also other arthropods, such as spiders and harvestmen, and even snails or small vertebrates. Seeds are also eventually included in their diet.

Feeding on a dead cockraoch. Photo by iNaturalist user bellumknight.**

The behavior of these ants is very complex and they are very resilient, being able to adapt to both drought and flooding conditions. For example, when the soil gets covered by water, they link together and form a ball or raft that floats.

Due to its broad diet and ability to live in several habitat types, including forests and open areas, the red imported fire ant adapts very easily to new areas, and this is exactly what happened.

The red imported fire ant arrived in the United States through the seaport of Mobile, Alabama, by cargo ship, in the 1930s or 1940s and the estimations are that about 9 to 20 unrelated queens were introduced during this time. During the next decades the colonies started to spread across the southern United States and Northern Mexico, causing serious environmental and economic damage.

A raft of floating red imported fire ants during a flood. Photo by Wikimedia user TheCoz.*

Studies have shown that many native arthropods disappear from an area when the red imported fire ants arrive. Some of them become prey of the ants and others are likely displaced by competition or because the ants remove their food source. For humans, the economic impact is mostly related to their presence in plantations, where they may remove germinating seeds. If nests are built near or under roads, pavements or buildings, the soil that is displaced can eventually damage the foundations of the structure. In human-inhabited areas they can be a nuisance because of their aggressive behavior, which makes outside activities difficult.

When threatened, fire ants react with an aggressive attack in which several workers approach the threat and sting it. Their venom is formed by a mix of many compounds and, in humans, often cause a burning sensation followed by urticaria and pustule formation. Allergic people may suffer serious and life-threatening allergic reactions.

More recently, the red imported fire ant’s invasion continued and it reached the Caribbean, China, Taiwan, Australia and New Zealand. There are also non-confirmed reports of its occurrence in India and the Philippines.

Due to this combination of factors, the red imported fire ant is one more species in the list of the top 100 invasive species in the world, just like the Giant African Snail and the New Guinea Flatworm, which I presented some weeks ago.

I have to say that I find it funny to see that their presence in gardens is a problem for outside activities in the USA. As a Brazilian I spend my whole childhood playing in a backyard full of fire ants and lost count of how many times I accidentally stepped onto a nest and ended up with my foot covered by stings. Ye goode olde times.

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References:

Ascunce, M. S., Yang, C. C., Oakey, J., Calcaterra, L., Wu, W. J., Shih, C. J., … & Shoemaker, D. (2011). Global invasion history of the fire ant Solenopsis invicta. Science, 331(6020), 1066-1068. https://science.sciencemag.org/content/331/6020/1066.full

Morrison, L. W. (2002). Long‐term impacts of an arthropod‐community invasion by the imported fire ant, Solenopsis invicta. Ecology, 83(8), 2337-2345. https://doi.org/10.1890/0012-9658(2002)083[2337:LTIOAA]2.0.CO;2

Morrison, L. W., Porter, S. D., Daniels, E., & Korzukhin, M. D. (2004). Potential global range expansion of the invasive fire ant, Solenopsis invicta. Biological invasions, 6(2), 183-191. https://doi.org/10.1023/B:BINV.0000022135.96042.90

Wikipedia. Red Imported Fire Ant. Available at < https://en.wikipedia.org/wiki/Red_imported_fire_ant >. Access on 15 April 2021.

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* This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

** This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

Friday Fellow: Puerto Rican Glasscup

by Piter Kehoma Boll

If you ever happen to walk in the woods, or sometimes in open spaces as well, and find a series of small often semitransparent cup-like mushrooms protruding from the soil or vegetation, you may be in front of a peculiar group of fungi, the glasscups, which make up the genus Orbilia. Today we will talk about one of these species that is found in Puerto Rico, Orbilia jesu-laurae, which I decided to call the Puerto Rican glasscup.

As most fungus, the glasscups have two life stages, a sexual and an asexual one. During the sexual stage, the Puerto Rican Glasscup produces small circular fruiting bodies measuring only about 1.5 mm in diameter with a light-brown to orange-brown color. Their margins may be somewhat undulating, disrupting the aspect of a perfect circle.

Fruiting bodies of the Puerto Rican glasscup. Extracted from Quijada et al. (2020).

When the fruiting bodies release spores in the environment, they will germinate and originate the asexual stage, which will grow in the substrate to form a network of hyphae, the mycelium, as typical of most fungi. However, while most fungi are parasites or saprotrophs during this stage, the Puerto Rican Glasscup is a predator.

Growing across the substrate, the mycelium of the Puerto Rican Glasscup looks for small nematodes, which are very common in the environment, and traps them with the hyphae. Once the nematode is trapped, the fungus will grow hyphae inside it, feeding on its tissues.

Capture of a nematode by the Puerto Rican glasscup. The nematode is near the hyphae in C1, captured by the hyphae, but still alive, in C2 to C3, and dead and filled by hyphae in C4. Photo extracted from Quijada et al. (2020).

The glasscup still feeds on decomposing plant material, though. In fact, the reason for it consuming nematodes is probably because they provide a good source of nitrogen, which may not be very available in the substrate. Thus, they act more or less like carnivorous plants.

Not all glasscups seem to be predators, but many are. Nematodes are the most common prey but some species may feed on other small animals, especially small arthropods such as copepods, collembolans, dipterans and mites. As many nematodes, and other of the eventually consumed small animals, are plant pests, it has been suggested that glasscups may be used as a biological control of these creatures, but there are no studies addressing the viability of such method yet.

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References:

Moosavi, M. R., & Zare, R. (2020). Fungi as biological control agents of plant-parasitic nematodes. In Plant defence: biological control (pp. 333-384). Springer, Cham. https://www.researchgate.net/profile/Rasoul-Zare/publication/227255809_Fungi_as_Biological_Control_Agents_of_Plant-Parasitic_Nematodes/links/09e4150b346c874d3a000000/Fungi-as-Biological-Control-Agents-of-Plant-Parasitic-Nematodes.pdf

Quijada, L., Baral, H. O., Beltrán-Tejera, E., & Pfister, D. H. (2020). Orbilia jesu-laurae (Ascomycota, Orbiliomycetes), a new species of neotropical nematode-trapping fungus from Puerto Rico, supported by morphology and molecular phylogenetics. Willdenowia, 50(2), 241-251. https://doi.org/10.3372/wi.50.50210

Friday Fellow: Broadlef Sea Lettuce

by Piter Kehoma Boll

If you are used to go to the beach, especially rocky shores, you my have seen some small green “leafy” things growing on the rocks and sometimes washed ashore that look like small lettuce plants or something like that. Well, those are green algae of the species Ulva lactuca, commonly known as sea lettuce. However, as this name is also used for other species of Ulva, the name broadleaf sea lettuce is sometimes used to refer to this specific species.

Broadlef sea lettuce growing around Sand Diego, USA. Photo by iNaturalist user annegero-stillwell.*

The thallus of the broadleaf sea lettuce is very thin and semitransparent, being only two cells thick. It often has a ruffled or torn margin and can grow up to 18 cm in length and 30 cm in width, but it is normally much smaller. It is attached to the substrate, often rocks, but sometimes other organisms, by a small disc-shaped holdfast.

As all plants, the broadleaf sea lettuce has a haploid phase (in which cells has only one chromosome of each) and a diploid phase (with two chromosomes of each per cell). Both phases have the same overall appearance, but the haploid plants are either male or female and release gametes into the water, which join to form a zygote, which will grow to form a diploid plant. This, in turn, releases movable spores (zoospores), which will germinate to produce new haploid plants.

A specimen in northern France. Photo by iNaturalist user simondenis142857.*

The broadleaf sea lettuce has a worldwide distribution, being found in all continents and oceans. It is an edible alga and is particularly rich in iron and the amino acid histidine. However, one must have caution about where it is harvested for consumption, as it can accumulate heavy metals in polluted zones.

Specimen from Rio de Janeiro, Brazil. Yummy, isn’t it? Photo by Ricardo da Silva Ribeiro.*

In nutrient-rich waters due to pollution, the populations of the broadleaf sea lettuce can grow very quickly and thousands of individuals may end up washed ashore. When they start to decompose, they emit toxic gases such as hydrogen sulfide, which may kill animals by hypoxia, i.e., lack of oxygen, as it inhibits cellular respiration. There are records of humans dying after walking near large amounts of decomposing algae.

Lifeforms often have this dual nature, and the same thing that can make you stronger can also kill you.

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References:

Dominguez, H., & Loret, E. P. (2019). Ulva lactuca, a source of troubles and potential riches. Marine drugs, 17(6), 357. https://doi.org/10.3390/md17060357

Wikipedia. Ulva lactuca. Available at < https://en.wikipedia.org/wiki/Ulva_lactuca >. Access on 1 April 2021.

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