Friday Fellow: Common Lungwort

by Piter Kehoma Boll

Blue is a relatively rare color in nature, but in some places it appears much more than in others. Flowers of plants in the family Boraginaceae are often blue. The forget-me-not is possibly the most popular example, but not the only one. Today our fellow is another blue flowered species that is also popular, not so much for its flowers though, but for its lung-like leaves, the common lungwort Pulmonaria officinalis.

The spotted leaves of the common lungwort are said to resemble diseased lungs. Photo by Jakob Fahr.*

Whenever you find a plant whose name refers to a body part, it most likely has to do with the ancient doctrine of signatures, the idea that a plant that resembles a human organ can be used to treat diseases on that organ. This is the case with the common lungwort and the common liverwort, which was presented here some time ago. The oval and kind of heart-shaped leaves of the common lungwort are slightly hairy on the upper side and marked by several white or pale spots. They were thought to represent an ulcerated lung and, therefore, used to treat diseases of the lungs. Although some studies revealed that lungwort extracts can present biological properties such as antioxidant, anti-inflammatory and wound healing activities, nothing has been found that is directly related to the lungs.

Found across most of continental Europe, the common lungwort is a small plant formed by a creeping rhizome from which the leaves sprout in the form of rosettes. It likes to grow on the forest floor, below the tree canopy, but dislikes places with too much shade. As a European species, it is very tolerant to cold, supporting temperatures as low as -29 °C.

The flowers of the common lungwort start red and slowly turn to blue as they age. Photo by iNaturalist user laivoi.*

In spring, between March and May, the flowers appear in inflorescences on elongated stems that grow from the leaf rosettes. They grow during a period in which the trees are only starting to produce new leaves so the flowers are fully exposed to the sun. Each inflorescence has 5 to 15 hermaphrodite flowers with five petals. The flowers start red and, as they age, they change color to purple and finally blue. This change in color occurs because the pigments are anthocyanins that are affected by pH, being red in acidic environments and blue in alkaline ones. The main pollinators of the common lungwort are bees and the plant only wants them to visit young, red flowers. As a result, the change in color helps direct the pollinators to the right flowers by signalling that the blue ones are uninteresting (and they, in fact, have no nectar anymore). But why does the plant keep flowers for longer periods instead of shedding the petals and producing fruits at once? Well, because the more flowers you have, the more pollinators you can attract from the distance. A large number of flowers makes you visible from far away but, as the pollinators come closer, the different colors guide them to the right spot.

Although they are too old to be pollinated, blue flowers are still useful in attracting pollinators for the younger, red flowers. Photo by iNaturalist user oburridge.*

The fruit of the common lungwort is a schizocarp, i.e., a small and dry fruit that splits into smaller portions, each containing a seed. In the case of the common lungwort, each fruit contains four seeds, and their main dispersers are ants. The ants collect the fruits, carry them to their colonies and feed the larvae with the fleshy portion, discarding the seed afterward.

The common lungwort is a popular plant because of its color-changing flowers and its resistance to cold, but, as we can see, this beauty hides an even deeper beauty caused by its interaction with the small creatures that share the same space with it.

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References:

Chauhan, S., Jaiswal, V., Cho, Y. I., & Lee, H. J. (2022). Biological Activities and Phytochemicals of Lungworts (Genus Pulmonaria) Focusing on Pulmonaria officinalis. Applied Sciences, 12(13), 6678. https://doi.org/10.3390/app12136678

Meeus, S., Brys, R., Honnay, O., & Jacquemyn, H. (2013). Biological flora of the British Isles: Pulmonaria officinalis. Journal of Ecology, 101(5), 1353-1368. https://doi.org/10.1111/1365-2745.12150

Wikipedia. Pulmonaria officinalis. Available at < https://en.wikipedia.org/wiki/Pulmonaria_officinalis >. Access on 22 September 2022.

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

Friday Fellow: Lined Earwig

by Piter Kehoma Boll

Of the 334 Friday Fellows that this blog had so far, 50 were insect. Yet, several insect orders have not been represented yet. One of them is the order Dermaptera, commonly known as earwigs, but this changes today. And the first species of this order to be featured here is Doru taeniatum, the lined earwig.

Occurring across the Americas, at least from the United States to Argentina, the lined earwig is often found in human crops, especially corn/maize. It has the typical appearance of most earwigs. The body is elongated, mostly brown, darker, almost black at the abdomen and reddish at the head. The antennae are a bit long and simple, the legs are yellowish and the wings consist of a small and hardened anterior pair, which resembles the elytra of beetles, and a larger and membranous posterior pair that keeps folded under the anterior pair when they are not being used to fly. The elytra are yellow, with a brown stripe running along the margin where both wings touch, causing a pattern of the yellow stripes separated by a brown stripe. And like all earwigs, the lined earwig has a pair of forceps-like cerci at the tip of the abdomen.

A male lined earwig in Pirassununga, Brazil. Photo by Antonio Bordignin.*

The lined earwig is a predator and feeds on other insects, especially eggs and small larvae, although it has also been observed ingesting plant matter, such as pollen and leaf tissues. One of its prey is the fall armyworm, Spodoptera frugiperda, a moth that is a major pest of crops, especially maize. The lined earwig feeds on both the eggs and caterpillars of S. frugiperda and is considered one of its most important predators, so its presence in maize plantations is always good, and, sometimes, when its numbers are large enough, no other form of pest control is needed.

A female on a human hand to give a perspective of size. Photo by David Aragonés Borrego.*

The predators of the lined earwig include other arthropods, such as ants and spiders, as well as vertebrates, such as anurans and possibly birds. Its defense mechanisms include both the use of the cerci to pinch the predator, mostly small ones, as well as a chemical defense, which consists of a spray that is released by glands that open at the fourth abdominal segment. This spray consists of quinones with a strong odor that can deter predators such as frogs and ants.

Being active both day and night, the lined earwig spends most of its life on maize plants. They use the space between the leaf and the stem of the plant as shelter, mating site and egg deposit. Males are larger than females, having larger elytra and larger cerci. Each maize plant often has only one earwig or a pair consisting of a male and a female living together. When a male wants to copulate, he approaches the female by moving his antennae near her, then moves to her side and strokes her abdomen with his cerci. If she accepts to copulate, they position themselves in opposite directions and connect the final segments of their abdomens, when the male then extrudes its genitalia and inserts them into the genital pouch of the female. Males are territorial and will fight other males that invade their territory, using the cerci to attack each other.

A female taking care of her eggs in Copándaro, Mexico. Photo by iNaturalist user ekdelval.*

After the pair mates, the female lays the eggs and takes special care of them. She frequently cleans them with her mouth, preventing infection by fungi and mites. She also defends them aggressively using her cerci as a weapon to pinch any intruder. After the eggs hatch, the female still takes care of the nymphs for a few days before they disperse in the environment and start to clean the crops from pests just like their parents did.

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References:

Briceño, R. D., & Schüch, W. (1988). Reproductive biology and behavior of Doru taeniatum (Forficulidae). Revista de Biologia Tropical, 36(2B), 437-440. https://revistas.ucr.ac.cr/index.php/rbt/article/view/23851

Eisner, T., Rossini, C., & Eisner, M. (2000). Chemical defense of an earwig (Doru taeniatum). Chemoecology, 10(2), 81-87. https://doi.org/10.1007/s000490050011

Jones, R. W., Gilstrap, F. E., & Andrews, K. L. (1988). Biology and life tables for the predaceous earwig, Doru taeniatum [Derm.: Forficulidae]. Entomophaga, 33(1), 43-54. https://doi.org/10.1007/BF02372312

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

Friday Fellow: Gold-Mouth Sea Squirt

by Piter Kehoma Boll

The closest relatives of vertebrates, the tunicates, are very unusual yet very diverse. In more than 300 Friday Fellows, we had not had a tunicate yet, but this changes today. To introduce this interesting group of animals, I decided to bring the gold-mouth sea squirt, Polycarpa aurata, a member of the class Ascidiacea, known as ascidians or sea squirts.

Also known as ox heart ascidian or ink-spot sea squirt, the gold-mouth sea squirt is found in coral reefs of the Indo-Pacific around southeast Asia and northern Australia. The adults are sessile urn-shaped animals measuring up to 15 cm in height. Their color is often a mix of white, purple and yellow in the shape of irregular spots and lines. The hollow body has two siphons, one at the top and one on the side. The inside border of the siphons is gold-yellow, hence the name gold-mouth sea squirt.

Several specimens growing side by side near Sulawesi. Photo by Bernard Dupont.*

Like all tunicates, the gold-mouth sea squirt is a filter feeder. It takes in water through the top siphon, filters it in the pharynx, which has several gill slits, and expels it through the lateral siphon. This process is also used for respiration. The filtered particles pass through the digestive system and the feces are eliminated through the anus, which opens internally into the lateral siphon.

Like all ascidians, the gold-mouth sea squirt is a hermaphrodite. Since it is a sessile organism, it reproduces by releasing sperm and eggs into the water, where fertilization occurs. The zygote develops into a swimming larva that resembles a tadpole and this larva eventually settles on the substrate, head down, and develops into the adult.

A whiter specimen with a fat ass surrounded by some small fish. Photo by Cheryl Gilbert.**

Various compounds have been isolated from the gold-mouth sea squirt and other ascidians, many of which show antimicrobial, antitumor, antioxidant and anti-inflammatory activity, among others. Most of these compounds do not seem to be synthesized by the ascidians themselves, but by the highly diverse community of microorganisms that live in and on their bodies, including many species of bacteria (especially cyanobacteria) and archaea, most of which, as you may have deduced, have not been described yet.

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References and further reading:

Casertano, M., Imperatore, C., Luciano, P., Aiello, A., Putra, M. Y., Gimmelli, R., … & Menna, M. (2019). Chemical investigation of the indonesian tunicate Polycarpa aurata and evaluation of the effects against Schistosoma mansoni of the novel alkaloids polyaurines A and B. Marine drugs, 17(5), 278. https://doi.org/10.3390/md17050278

de Gier, W., Groenhof, M., & Fransen, C. H. (2022). Coming out of your shell or crawling back in: multiple interphylum host switching events within a clade of bivalve-and ascidian-associated shrimps (Caridea: Palaemonidae). Contributions to Zoology, 1(aop), 1-33. https://brill.com/view/journals/ctoz/91/3/article-p166_002.xml

Erwin, P. M., Pineda, M. C., Webster, N., Turon, X., & Lopez-Legentil, S. (2014). Down under the tunic: bacterial biodiversity hotspots and widespread ammonia-oxidizing archaea in coral reef ascidians. The ISME journal, 8(3), 575-588. https://doi.org/10.1038/ismej.2013.188

Wang, W., Oda, T., Fujita, A., Mangindaan, R. E., Nakazawa, T., Ukai, K., … & Namikoshi, M. (2007). Three new sulfur-containing alkaloids, polycarpaurines A, B, and C, from an Indonesian ascidian Polycarpa aurata. Tetrahedron, 63(2), 409-412. https://doi.org/10.1016/j.tet.2006.10.060

Wikipedia. Polycarpa aurata. Available at < https://en.wikipedia.org/wiki/Polycarpa_aurata >. Access on 8 September 2022.

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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-ShareAlike 4.0 International License.

Friday Fellow: Horn of Plenty

by Piter Kehoma Boll

In the European summer, if you are walking among beech or oak trees, you may end up seeing some interesting mushrooms growing in the leaf litter. Funnel-shaped and strongly black in color, they may be hard to spot and appear as holes in the ground. These are the fruiting bodies of Craterellus cornucopioides, a fungus known as horn of plenty, black chanterelle, or trumpet of the dead.

Horn of plenty growing in Ukraine. Photo by Eva Andrik.*

As most mushrooms that you find popping out of the ground in forests, the horn of plenty is a mycorrhizal species, i.e., its mycelium grows associated with the roots of trees in a mutualistic partnership. In the case of the horn of plenty, the trees are mostly beeches and oaks or other broad-leaved species.

A lateral view of a fruiting body growing in the United Kingdom. Photo by Max Mudie.*

The horn of plenty looks beautiful with all its blackness but probably not very tasty at first. It is, however, an edible species and, apparently, very tasty as well. When dried, it is said to acquire black truffle notes. A very nutritious mushroom, it contains a high amount of protein and considerable levels of vitamin C and, even more importantly, vitamin B12 in levels above those found in most mushrooms, which can be important for vegans since finding vitamin B12 in non-animal sources is very hard.

More than being a good source of proteins and vitamins, the horn of plenty is also rich in antioxidants, compounds that help prevent cancer and slow down aging. Horn of plenty seems to be a very adequate name for this fellow, right?

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References:

Kosanić, M., Ranković, B., Stanojković, T., Radović-Jakovljević, M., Ćirić, A., Grujičić, D., & Milošević-Djordjević, O. (2019). Craterellus cornucopioides edible mushroom as source of biologically active compounds. Natural Product Communications, 14(5), 1934578X19843610. https://doi.org/10.1177/1934578X19843610

Watanabe, F., Schwarz, J., Takenaka, S., Miyamoto, E., Ohishi, N., Nelle, E., … & Yabuta, Y. (2012). Characterization of vitamin B12 compounds in the wild edible mushrooms black trumpet (Craterellus cornucopioides) and golden chanterelle (Cantharellus cibarius). Journal of nutritional science and vitaminology, 58(6), 438-441. https://doi.org/10.3177/jnsv.58.438

Wikipedia. Craterellus cornucopioides. Available at < https://en.wikipedia.org/wiki/Craterellus_cornucopioides >. Access on 25 August 2022.

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

Friday Fellow: Coarse Tassel Fern

by Piter Kehoma Boll

After almost six years, we are back with a species of lycophyte, this time Phlegmariurus phlegmaria, commonly known as the coarse tassel fern. Despite this name, this species is not a true fern, but actually a club moss (which are not true mosses either…).

The coarse tassel fern has a widespread distribution from Africa to Southeast Asia and many Islands in the Indo-Pacific. This means that it is likely a complex of very similar species and not a single species. It occurs in shady places of tropical forests and grows on trees and other plants, often alongside true mosses and true ferns. Its scientific name, phlegmaria, is obviously related to phlegm, but I could not find anything stating that this plant was used medicinally for anything related to phlegm. Perhaps the name comes from the plant’s shape, as it lives hanging from trees as long, often yellowish strings? Ew…

Coarse tassel fern in the Cambridge University Botanic Garden. Photo by Magnus Manske.*

Across its native range, the coarse tassel fern is common in some areas and very rare in others. In Taiwain, for example, it is listed as an endangered species. Considering that different populations may be different species, this local threat may actually be a threat to a whole species. More molecular studies addressing different populations are necessary to make this issue clearer.

Phlegmariurus phlegmaria growing in New Caledonia. Photo by Leon Perrie.**

Recently, the complete chloroplast genome of the coarse tassel fern was sequenced. However, it was sequenced from specimens growing in China, and the type specimen for this species comes from India. Thus, in the future, we may end up discovering that the sequenced plant is from another, yet undescribed species of Phlegmariurus.

In traditional Chinese medicine, the coarse tassel fern has been used for the treatment of rheumatic pain, arthritis, traumatic injury, sore throat, edema, and urticaria. In Southeast Asia, it is also common to wash one’s hair using this plant in the belief that it stimulates hair growth, probably because of the ancient belief that a plant resembling a body part could be used to treat diseases of that organ, as I mentioned while presenting the common liverwort.

Studies on the chemical constituents of the coarse tassel fern and other species of Phlegmariurus found some compounds that can be useful in the treatment of Alzheimer’s disease and related disorders. Some are present in related clubmoss genera, such as Huperzia, and are already marketed around the globe.

Species of Phlegmariurus, including the coarse tassel fern, are also cultivated as ornamental plants. Unfortunately, many plants that you can find for sale are extracted from the wild, which can lead to a serious reduction in the number of individuals in natural populations. So if you want to buy one of these to hang in your living room, be sure that it does not come from irresponsible exploitation of wild populations!

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References:

Field, A. R., & Bostock, P. D. (2013). New and existing combinations in Palaeotropical Phlegmariurus (Lycopodiaceae) and lectotypification of the type species Phlegmariurus phlegmaria (L.) T. Sen & U. Sen. PhytoKeys, (20), 33. https://doi.org/10.3897%2Fphytokeys.20.4007

Tang, L. M., Jiang, R. H., & An, J. C. (2020). The complete chloroplast genome of Phlegmariurus phlegmaria, one representative species of genus Phlegmariurus. Mitochondrial DNA Part B, 5(3), 3418-3419. https://doi.org/10.1080/23802359.2020.1820392

Yang, Y., Wang, Z., Wu, J., & Chen, Y. (2016). Chemical constituents of plants from the genus Phlegmariurus. Chemistry & Biodiversity, 13(3), 269-274. https://doi.org/10.1002/cbdv.201500043

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

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

Friday Fellow: Bristly Millipede

by Piter Kehoma Boll

Millipedes make up a beautifully diverse group of arthropods. They do not only include the typical cylindrical critters with many legs that curl up into a spiral, but also astonishing long ones with more legs than you could imagine, some with the amazing ability to glow in the dark, and then there’s today’s species, Polyxenus lagurus, the bristly millipede.

You have to be very attentive to notice the bristly millipede, as it measures only 3 to 4 mm in length as an adult. And even if you do notice it, you may not think at first that it is a millipede. I mean, look at it at the image below. It is very short and fluffy, with its body all covered by small hair-like projections, or bristles, hence the name.

Would you think this is a millipede if you did not know this is a millipede? Photo by Andy Murray.**

The bristly millipede is found in Europe and North America and belongs to a very divergent group of millipedes, the Polyxenida. The exoskeleton of polyxenid millipedes is soft, not calcified as in most millipede species. Even so, they are very resistant to drought and occur often in dry places, such as among rocks or in the leaf litter of xeric (very dry) regions. The food of the bristly millipede consists mainly of lichens and algae, which it consumes mostly while they are dehydrated so that they provide little to no water.

How can this small bug survive in a dry environment eating dried-out food? Where does it get its water from? From the air, of course! A study found out that the bristly millipede can absorb water vapor directly from the air.

Just look at how amazing this creature is in all its details. Foto by Gilles San Martin.**

Despite its very small size, the bristly millipede can defend itself quite well, at least against arthropod predators, such as ants and spiders. When feeling threatened, the bristly millipede strokes the predators with its bristly “tail”. This makes several spines that form the tail be released on the surface of the predator’s body. These spines have recurved tips that hook onto the hairs on the surface of the predators and, as the predators try to groom themselves to get rid of the spines, they only get more and more entangled, as the spines start to hook onto each other. The predator becomes so entangled that it cannot move anymore and ends up dying slowly of starvation or dehydration.

The bristly millipede is a real fluffy badass.

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References:

Eisner, T., Eisner, M., & Deyrup, M. (1996). Millipede defense: use of detachable bristles to entangle ants. Proceedings of the National Academy of Sciences, 93(20), 10848-10851. https://doi.org/10.1073/pnas.93.20.10848

Wright, J. C., & Westh, P. (2006). Water vapour absorption in the penicillate millipede Polyxenus lagurus (Diplopoda: Penicillata: Polyxenida): microcalorimetric analysis of uptake kinetics. Journal of experimental biology, 209(13), 2486-2494. https://doi.org/10.1242/jeb.02280

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

The richest is not always the commonest: a lesson from flowering plants in a Cerrado outcrop

by Piter Kehoma Boll

The complexity of ecosystems is sustained by a variety of relationships that different species have with each other and that are often adapted to the environment in which they live. Although we usually think of relationships based on conflicts, such as predation, parasitism, and competition, beneficial relationships are almost as important and common, especially when we think of flowering plants, as many plant species rely on animals to pollinate them and disperse their seeds.

The different ways through which plants are pollinated are called pollination syndromes and include anemophily (pollination by wind), melittophily (by bees), phalenophily (by moths), sphingophily (by hawk moths), psychophily (by butterflies), myophily (by flies), cantharophily (by beetles), chiropterophily (by bats) and ornithophily (by birds), and there are generalist plants as well, whose flowers can be pollinated by several different animals. Now considering the way plants have their seeds dispersed, the classification is usually into only three categories: zoochory (by animals), anemochory (by wind), and autochory (by the plant itself, because why wait for animals or the wind? Ain’t nobody got time for that!).

Birds are among the many animals that can pollinate flowers (A) and disperse seeds (B). Image by Cássio Cardoso Pereira.*

We often think of bees and butterflies as the most common pollinators. Indeed bees are by far the most common and important, but actually very few plants rely exclusively on butterflies for pollination. Flies, beetles, moths, and even birds and bats often pollinate more plant species in a given ecosystem. Regardless of the ecosystem being a dense forest, an open grassland, or a shrubby savanna, bees are always the ones doing the job for most plant species.

Now regarding seed dispersal, the configuration of the ecosystem is much more important and causes drastic changes in the frequency of dispersal syndromes. In open areas such as grasslands and savannas, anemochory is often considered to be the predominant dispersal syndrome. In forests, however, zoochory would dominate, as there is not enough wind to blow seeds around.

When we survey the dispersal syndromes in forests, we find that most plant species have, indeed, their seeds dispersed by animals. However, a survey in grasslands and savannas can show results that look puzzling at first. Sometimes all three dispersal syndromes occur in the same proportion and sometimes lots of species continue to be dispersed by animals, while the wind is important only to a few. Were we wrong in our predictions then? Not necessarily.

One problem is that most studies, almost all actually, only compare pollination and dispersal syndromes by the number of species in that area. However, plant species are not evenly distributed in the environment. Some species have lots of individuals, being dominant in their ecosystems, while others occur in a much smaller number. Does the proportion of dispersal syndromes remain the same if we consider the number of individuals and not species? Not necessarily.

A recent study evaluated the pollination and dispersal syndromes of plants in an area of the Brazilian Cerrado biome, more specifically an area of Cerrado Rupestre (one of the less known Cerrado physiognomies). The researchers not only considered the distribution of the syndromes according to the number of species but also according to the number of individuals. Most plant species were pollinated by bees, as expected, and most individuals were pollinated by bees as well. However, while most species had their seeds dispersed by animals, most individuals had their seeds dispersed by wind. This means that, although most species rely on animals to disperse seeds, they tend to occur in a lower density, with fewer individuals per area. On the other hand, wind-dispersed species have a very high density, so most individuals in an area belong to them.

When we consider pollination and dispersal syndromes according to species or individuals, the picture can change drastically. Although most species are dispersed by animals in this Cerrado fragment (B), most plant individuals actually belong to species dispersed by wind (D). Credits to Pereira et al. (2022).*

When we consider the distribution of dispersal syndromes only according to species, the results seem to contradict what is expected for a savanna, but looking at it from the perspective of individuals makes it clear that the pattern follows the predictions.

Being aware of this is important for several reasons, especially to allow adequate management programs to protect such areas. The stability of an ecosystem does not depend solely on the species richness but also on the abundance of each species. By analyzing the distribution of dispersal syndromes from both perspectives, we can see that the wind is the main disperser for this ecosystem as a whole, but animals are still important dispersers to keep the species richness high and, in turn, a high richness of plant species is important to sustain the animal species. This makes our understanding of the whole system very different from what we would know from data on species alone. Now let’s hope future studies will start to address this issue from both perspectives as well.

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References:

Kuhlmann, M., & Ribeiro, J. F. (2016). Evolution of seed dispersal in the Cerrado biome: ecological and phylogenetic considerations. Acta Botanica Brasilica, 30, 271-282. https://doi.org/10.1590/0102-33062015abb0331

Pereira, C. C., Arruda, D. M., Soares, F. D. F. S., & Fonseca, R. S. (2022). The importance of pollination and dispersal syndromes for the conservation of Cerrado Rupestre fragments on ironstone outcrops immersed in an agricultural landscape. Neotropical Biology and Conservation, 17(1), 87-102. https://doi.org/10.3897/neotropical.17.e79247

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

Jaguars help deer eat bones, or: the food web is wild!

by Piter Kehoma Boll

We get used to thinking of the food chain, or more precisely the food web, as something considerably regular and flowing in a single direction: plants synthesize nutrients by photosynthesis, herbivores eat plants, carnivores eat herbivores and stuff. But nature does not work as regularly as we think and sometimes things can look very crazy.

Although many animals are strictly herbivores indeed, this is not exactly the case for many ungulates that we may see as vegan, such as ruminants. It is actually not that rare to find ruminants chewing on bones of dead animals, sometimes when they still have some flesh attached to them. The main reason for herbivores to eat bones is to acquire minerals, such as calcium, which are important not only for growing bones and horns or antlers but also for conducting nerve impulses and other biochemical roles.

Now observations with a single camera trap in Santa Rosa National Park in Costa Rica recorded more than a hundred events of white-tailed deer (Odocoileus virginianus) chewing on bones of turtle carcasses on a beach. The deer included males with growing antlers, lactating females, and growing fawns, all of which need additional amounts of calcium to grow antlers, replace calcium lost in milk production, and grow bones, respectively.

Ok, those deer eat a lot of turtle bones, so what? Well, the reason why there are so many bones available for them to feast on is that jaguars prey on turtles that come to that beach to lay their eggs. Jaguars are among the most important predators in the Neotropics and deer are obviously one of their prey. While the presence of jaguars can be a threat to the life of the white-tailed deer, they are also essential to provide the bones on which the deer feed to get healthy.

Jaguars eat turtles on the beach and let their bones behind. Later, deer come to feed on the bones that their main predator left as a gift. “From jaguar to dear, with love, so that you can grow healthy and feed me later”. Credits to Morera et al. (2022).*

This almost turns the food web upside down, right? Or at least add some very weird loops in it.

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Reference:

Morera, B., Montalvo, V., Sáenz-Bolaños, C., Cruz-Díaz, J. C., Fuller, T. K., & Carrillo, E. (2022). Osteophagia of sea turtle bones by white-tailed deer (Odocoileus virginianus) in Santa Rosa National Park, northwestern Costa Rica. Neotropical Biology and Conservation, 17(2), 143-149. https://doi.org/10.3897/neotropical.17.e87274

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

Friday Fellow: Common Tusk Shell

by Piter Kehoma Boll

Mollusks make up the most speciose animal phylum after the arthropods, but only three of its classes are popular among the general public. One of the less known classes is Scaphopoda, which includes a group of mollusks known as tusk shells. Among the about 500 described species, one is named Antalis entalis, known as the common tusk shell.

The common tusk shell is found in the waters of the North Atlantic and, like all tusk shells, it spends most of its life buried in the sediments of the sea floor. Its body measures about 4 cm in length and is surrounded by an elongated shell that has an opening at each end, one end being narrower than the other. The wider opening is the one through which it extends its foot and a series of small tentacles known as captacula. Tusk shells lack eyes completely, at least as adults. Their free-swimming larvae have a brief stage in which very simple eyes occur.

Most of the body of the common tusk is permanently surrounded by the shell. Only its foot and very small tentacles, the captacula, are extended through the larger opening, as seen in the first shell of this image.

Due to the weird anatomy of tusk shells, it is hard to tell which part of their body is the anterior end or posterior end, or which is the dorsum and which is the venter, but this wider opening is often considered the ventral side or anterior end. The narrower opening at the other end of the shell is directed upward and is mainly used for respiration. Water enters through this opening, bringing oxygen, and leaves carrying carbon dioxide away.

As adult common tusk shells never leave the sediment voluntarily, they feed on other organisms that live on the same substrate, with foraminifers making up a large portion of their diet. They use the captacula to capture their prey and ingest them. The feces are eliminated through the anus, which is located at the same wider opening of the shell.

Although about 500 hundred extant species of tusk shells have been described, we know very little of their ecology and it is even hard to find photographs of living specimens. The common tusk shell is one of the most studied species, but these studies are related to its anatomy, distribution, and embryonic development, as well as phylogenetic studies. The importance of tusk shells to marine ecosystems is largely unknown.

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References:

Antalis entalis (Linnaeus, 1758) in GBIF Secretariat (2021). GBIF Backbone Taxonomy. Checklist dataset https://doi.org/10.15468/39omei accessed via GBIF.org on 2022-07-28.

Reynolds, P. D. (2002). The scaphopoda. Advances in marine biology, 42, 137-236. https://doi.org/10.1016/S0065-2881(02)42014-7

Wollesen, T., McDougall, C., & Arendt, D. (2019). Remnants of ancestral larval eyes in an eyeless mollusk? Molecular characterization of photoreceptors in the scaphopod Antalis entalis. EvoDevo, 10(1), 1-12. https://doi.org/10.1186/s13227-019-0140-7

Friday Fellow: Red Foram

by Piter Kehoma Boll

In the warm waters of the North Atlantic, especially in the Caribbean Sea and the Gulf of Mexico, we can find one of the most amazing foraminifers. Its scientific name is Homotrema rubrum and it is sometimes called the red foram.

This is once again a large foraminifer, easily visible to the naked eye, although not as large as some other species. They are a sessile, encrusting foraminifer that grows on the surface of rocks, shells and corals, and you can detect them as small, often irregular red plates measuring a few millimeters in size on the surface of hard substances. In some places, such as Bermuda, they are so abundant that the sand of the beaches acquired a pink color due to the huge number of skeletons of dead red forams washed ashore.

Some red forams growing on a coral reef in Bermuda, one of the most iconic places where this species is found in abundance. Photo by Ben Eddy.*

Like all foraminifers, the red foram is a single-celled organism and, although some sources that I consulted stated that it is a colonial species, I understood that every red “plate” is actually a single cell, although sometimes you can find several of them nearby and even a bit overlapped.

A piece of dead coral covered by numerous skeletons of dead red forams in Bonaire, with a human hand for size comparison. Photo by Ali and Brice.*

The red shell that surrounds the cell of the red foram can have one or many openings through which this lovely protist extends its reticulopodia—the long, narrow, branching and anastomosing pseudopodia—to capture prey. For some time it was thought that the main, and perhaps only, food of the red foram were small unicellular algae, but now it is known that they feed on other organisms as well, including some small crustaceans. They are true predators!

But there are other surprises about this little fellow. To help it capture its prey, it collects sponge spicules (the small needle-like structures that form the skeleton of sponges) and embeds them into its own cell, using them to improve the support of its reticulopodia. It is almost like a single-celled organism using tools to eat! (Ok, this may be a little bit of a stretch).

In this specimen from Florida, USA, you can see the collected sponge spicules appearing as several small sets of needle-like structures. Photo by Jeff Goddard.*

Like other encrusting foraminifers, the red foram likes to grow inside cracks, crevices and other spaces of coral reefs. As its shell consists of magnesium calcite, it helps reinforce the coral framework and provides carbonate for the corals to grow as well. Thus, they are very important to make the reefs more resistant to climate change since the raise in CO2 levels is making the oceans more acidic, which increases coral reef erosion.

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References:

Elliott, J. M., Logan, A., & Thomas, M. L. H. (1996). Morphotypes of the foraminiferan Homotrema rubrum (Lamarck): distribution and relative abundance on reefs in Bermuda. Bulletin of Marine Science, 58(1), 261-276. https://www.ingentaconnect.com/content/umrsmas/bullmar/1996/00000058/00000001/art00016

Phalen, W. G. (2015). Homotrema rubrum (Lamarck): distribution and biology of a potential reef bioindicator and underwater angler (Doctoral dissertation, University of Georgia). https://esploro.libs.uga.edu/esploro/outputs/graduate/Homotrema-rubrum-Lamarck-distribution-and-biology/9949333258902959

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