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.
Specimen with yellow flowers in Argentina. Photo by iNaturalist user Fede y Vani.
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.
Specimen in Taiwan with one of the most typical flower colors, between yellow and red. Notice how the outer, older flowers are redder, and the inner ones are not even open yet. Photo by iNaturalist user 葉子.
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.
In Australia the common lantana has become an enemy almost as worse as capitalism. Photo by Adam Morris.
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.
– – –
References:
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
Seafood is often a highly regarded food all around the world and include all sorts of marine organisms that humans found out that are edible. In Southeast Asia, one of these delicacies is a sea cucumber, Thelenota ananas, known as pineapple sea cucumber, tripang or prickly redfish.
A nice pineapple sea cucumber in the Maldivas. Photo by Albert Kang.*
The pineapple sea cucumber is an echinoderm, a group which also includes seastars, brittle stars, sea urchins, sand dollars and sea lilies. It is found in tropical and subtropical waters of the Indo-Pacific, occurring from the Red Sea southward along the east coast of Africa and eastward to Polynesia, being common in coral reefs, although in low densities.
Reaching up to 70 cm in length and 6 kg in weight, the pineapple sea cucumber is a relatively large sea cucumber. It has a reddish-orange and black color, usually brighter on the underside, and has many soft star-like projections (“teats”) all over the body.
A detail showing the star-shaped “teats”. Photo by Nick Hobgood.**
Like most sea cucumbers, the pineapple sea cucumber is a herbivore. As a larva it probably feeds on phytoplankton and, as an adult, on larger algae, including calcaerous green algae of the genus Halimeda. It grows slowly and has a long lifespan. In more subtropical areas, it reproduces in summer, from January to March, but in more tropical waters it is likely that it reproduces all year round. It can also involuntarily reproduce asexually if accidentally cut in half, with the anterior and posterior halves forming a new organism in a few weeks.
In the Northern Mariana Islands, with a human arm for comparison. Photo by John Starmer.*
As I said above, the pineapple sea cucumber is edible and is, in fact, a very healthy and promising food. As all sea cucumbers, it contains a fucoidan, a type of polysaccharide also found in brown algae and that has antioxidant and antiinflammatory properties. It is also rich in saponins, like other sea cucumbers and echinoderms, and these revealed to be good agents to reduce cholesterol levels and also have anticancer properties. More than that, the pineapple sea cucumber contains another compound, a glycosaminoglycan known as fucosylated chondroitin sulfate (FuCS-1), which revealed to have the ability to block HIV from entering cells and has, therefore, the potential to be explored for the development of new anti-HIV drugs, especially against some resistant variants.
A very red specimen in Malaysia. Photo by Tsu Soo Tan.*
Unfortunately, due to its slow development, the reproductive rate of the pineapple sea cucumber is unable to compensate its extraction from the ocean for human consumption. As a result, the natural populations have drastically decreased in the past decades, with a 60% reduction in New Caledonia and being almost extinct in some areas. As a result, it is listed as endangered in the IUCN’s red list. If we don’t start to respect this species by applying severe policies for harvesting it, we will end up losing a very precious fellow of our planet.
Conand C (1993) Reproductive biology of the holothurians from the major communities of the New Caledonian Lagoon. Marine Biology 116:439–450. https://doi.org/10.1007/BF00350061
Han Q, Li K, Dong X, Luo Y, Zhu B (2018) Function of Thelenota ananas saponin desulfated holothurin A in modulating cholesterol metabolism. Scientific Reports 8:9506. https://doi.org/10.1038/s41598-018-27932-x
Huang N, Wu M-Y, Zheng C-B, Zhu L, Zhao J-H, Zheng Y-T (2013) The depolymerized fucosylated chondroitin sulfate from sea cucumber potently inhibits HIV replication via interfering with virus entry. Carbohydrate Research 380:64–69. https://doi.org/10.1016/j.carres.2013.07.010
Reichenbach (1995) Potential for asexual propagation of several commercially important species of tropical sea cucumber (Echinodermata). Journal of the World Aquaculture Society 26(3):272–278. https://doi.org/10.1111/j.1749-7345.1995.tb00255.x
Yu L, Xue C, Chang Y, Xu X, Ge L, Liu G, Wang Y (2014) Structure elucidation of fucoidan composed of a novel tetrafucose repeating unit from sea cucumber Thelenota ananas. Food Chemistry 146:113–119. https://doi.org/10.1016/j.foodchem.2013.09.033
Mayflies make up the order Ephemeroptera, one of the oldest ones among insects. Closely related to dragonflies and damselflies (order Odonata), mayflies have an aquatic nymph and a terrestrial imago (i.e., adult). One considerably well-known species is Heptagenia sulphurea, commonly known as the yellow mayfly or yellow may dun.
Native from Europe, the yellow mayfly lives most of its life as a nymph. It prefers running and clean waters, where it lives under stones and feeds on decaying plant matter and associated bacterial biofilms. The nymph has a flattenned body of a dark color with several yellowish marks. The legs are short and white and have a series of alternating yellow and black sinuous transversal stripes. Like in all mayfly nymphs, the abdomen has visible gills on both sides and three longe cerci (tails) at the tip. During its final stage as a nymph, the yellow mayfly is about 1 cm long.
Most mayflies are very sensitive to pollution and the yellow mayfly is one of the most sensitive of all, at least in Europe. Whenever the water of a streams starts to get polluted, the yellow mayfly is the first mayfly species to disappear. Thus, its presence indicates water of very good quality.
Different from all other insects, mayflies have an intermediate stage between the nymph and the imago stages, the so-called subimago. This stage is already terrestrial like the imago and already has wings, although they are often less developed, making them poor fliers. This subimago stage is commonly known as dun and, in the yellow mayfly, it has a typical yellow color, hence the common name yellow may dun. Females have black and poorly developed eyes, while in males the eyes are larger and vary from dark gray to whitish. Nymphs molt into subimagos beginning in May, when the peak occurs, but may appear as late as July.
Male imago of the yellow mayfly in Russia. Photo by Vladimir Bryukhov.*
When the subimago molts into the adult, usually after only a few days, the body becomes light brown and the eyes whitish in both sexes, but the eyes are still smaller in females than in males. Adults have the sole purpose of reproducing and so they do. After mating, the male dies in a few hours, and so does the female after laying her eggs in a stream.
The yellow mayfly is often used as a fishing bait. Once a common species across Europe, its populations have decreased considerably in the last century due to the increase of water pollution. Some recent efforts to despolute streams may, fortunately, help this and other mayfly species to find again more room to thrive.
Parasites are special types of organisms that live on or inside other lifeforms, slowly feeding on them but usually not killing them, just reducing their fitness to some degree. This is a much more discrete way to survive than killing or biting entire parts off, as predators (both carnivores and herbivores) do. However, different from these creatures, parasites are often regarded as unpleasant and disgusting. Yet parasitism is the most common way to get food in nature.
When I introduced the rhinoceros tick in a recent Friday Fellow, I mentioned the dilemma caused by it. Since the rhinoceros tick is a parasite of rhinoceroses, and rhinoceroses are threatened with extinction, a common practice to improve the reproductive fitness of rhinos is removing their ticks, but this may end up leading the rhinoceros tick to extinction.
This actually happened already with other parasites, such as the louse Coleocephalum californici, which was an exclusive parasite of the California condor Gymnogyps californianus. In order to save the condor, a common practice among veterinarians working with conservationists was to delouse the birds and, as a result, this louse is now extinct. The harm that the louse caused to the condor was so little, though, that its extinction was not at all necessary, being nothing more than a case of negligence and lack of empathy for a small and non-charismatic species.
The louse Rallicola (Aptericola)pilgrimi has also vanished forever during the conservation campaigns to save its host, the little spotted kiwi, Apteryx owenii, in another failed work.
The efforts to save the little spotted kiwi, Apteryx owenii, from extinction led to the extinction of its louse. Photo by Judi Lapsley Miller.*
The now extinct Rallicola (Aptericola) pilgrimi. Credits to the Museum of New Zealand.***
Another group of parasites that is facing extinction are fleas. The species Xenopsyllanesiotes was endemic to the Christmas Island together with its host, the Christmas Island rat, Rattus macleari. The introduction of the black rat, Rattus rattus, in the island led to a quick decline in the population of the Christmas Island rat, which went extinct at the beginning of the 20th century and, of course, the flea went extinct with it. The flea Acanthopsylla saphes has likely become extinct as well. It was a parasite of the eastern quoll, Dasyurus viverrinus, in mainland Australia. The eastern quoll today is only found in Tasmania, as the mainland Australia’s population went extinct in the mid-20th century. However, the flea was never found in the Tasmanian populations, so it is likely that it died away in mainland Australia together with the local population of its host.
The Manx shearwater flea Ceratophyllus (Emmareus) fionnus. Photo by Olha Schedrina, Natural History Museum.*
But things have been changing lately and fortunately the view on parasites is improving. A recent assessment was made on the population of another flea, the Manx shearwater flea, Ceratophyllus (Emmareus) fionnus. This flea is host-specific, being found only on the Manx shearwater Puffinus puffinus. Although the Manx shearwater is not at all a threatened species and has many colonies along the North Atlantic coast, the flea is endemic to the Isle of Rùm, a small island off the west coast of Scotland. Due to the small population of its host in this island, the flea has ben evaluated as vulnerable. If the Manx shearwater population in the Island were stable, things would be fine but, as you may have guessed already, things are not fine. Just like it happened in Christmas Island, the black rat was also introduced in the Isle of Rúm and has become a predator of the Manx shearwater, attacking its nests.
The Manx shearwater, Puffinus puffinus, is the sole host of the Manx shearwater flea. Photo by Martin Reith.**
Some ideas have been suggested to protect the flea from extinction. One of them is to eradicate the black rat from the Isle or at least manage its population near the Manx shearwater colonies. Another proposal is to translocate some fleas to another island to create additional populations in other Manx shearwater colonies.
But why bother protecting parasites? Well, there are plenty of reasons. First, they comprise a huge part of the planet’s biodiversity and their loss would have a strong impact on any ecosystem. Second, they are an essential part of their host’s evolutionary history and are, therefore, promoters of diversity by natural selection. Removing the parasites from a host would eventually decrease its genetic variability and let it more vulnerable to other new parasites. Due to their coevolution with the host, parasites are also a valuable source of knowledge about the host’s ecology and evolutionary history, helping us know their population dynamics. We can even find ways to deal with our own parasites by studying the parasites of other species, and parasites are certainly something that humans managed to collect in large numbers while spreading across the globe.
Parasites may be annoying but they are necessary. They may seem to weaken their host at first but, in the long run, what doesn’t kill you makes you stronger.
Kwak ML (2018) Australia’s vanishing fleas (Insecta: Siphonaptera): a case study in methods for the assessment and conservation of threatened flea species. Journal of Insect Conservation 22(3–4): 545–550. doi: 10.1007/s10841-018-0083-7
Kwak ML, Heath ACG, Palma RL (2019) Saving the Manx Shearwater Flea Ceratophyllus (Emmareus) fionnus (Insecta: Siphonaptera): The Road to Developing a Recovery Plan for a Threatened Ectoparasite. Acta Parasitologica. doi: 10.2478/s11686-019-00119-8
Rózsa L, Vas Z (2015) Co-extinct and critically co-endangered species of parasitic lice, and conservation-induced extinction: should lice be reintroduced to their hosts? Oryx 49(1): 107–110. doi: 10.1017/S0030605313000628
Parasites exist everywhere and, although most of us see them as hateful creatures, more than half of all known lifeforms live as a parasite at least in part of their life. And there are likely many more yet unknown parasites around there. Today I’m going to talk about one of them, which is found in large portions of Africa.
Its name is Dermacentor rhinocerinus, known as the rhinoceros tick. As its name suggests, it is a tick, therefore a parasitic mite, and its adult stage lives on the skin of the white rhinoceros (Ceratotherium simum) and the critically endangered black rhinoceros (Diceros bicornis).
A male rhinoceros tick attached to the skin of a rhinoceros in South Africa. Credits to iNaturalist user bgwright.**
Male and female rhinoceros ticks are considerably different. In males, the body has a black background with many large orange spots. In females, on the other hand, the abdomen is mainly black with only two round orange spots and the plate on the thorax is orange with two small dark spots. Males and females mate on the surface of rhinoceroses. After mating, the female starts to increase in size while the eggs develop inside her and then drops to the ground, laying the eggs there.
A female rhinoceros tick patiently waiting for a rhinoceros to come close. Photo by Martin Weigand.**
The larvae, as soon as they hatch, start to look for another host, usually a small mammal such as rodents and elephant shrews. They feed on this smaller host until they reach the adult stage, when they drop to the ground and climb on the surrounding vegetation, waiting for a rhinoceros to pass by and then attaching to them.
Conservation efforts to preserve biodiversity are mainly focused on vertebrates, especially mammals and birds. Rhinoceroses, which are an essential host for the rhinoceros tick to survive, are often part of conservation programs and, in order to increase their reproductive success, the practice of removing parasites from their skin is common. This is, however, bad for the rhinoceros ticks. If their host is endangered, they are certainly endangered too, and removing them worsens their condition. Are parasites less important for the planet? Don’t they deserve to live just as any other lifeform? We cannot forget that nature needs more than only what we consider cute.
Which of the two species shown below is more charismatic?
Tangara chilensis (Paradise Tanager). Photo by flickr user ucumari.*
Apocrypta guineensis (a fig wasp). Photo by Wikimedia user JMK.**
You probably would pick the first one. And if I’d ask you which one deserves more attention and efforts to be preserved, you would likely choose the bird as well, or at least most people would. But what is the problem with that? That’s what I am going to show you now.
As we all know, the protection of biological diversity is an important subject in the current world. Fortunately, there is an increase in campaigns promoting the preservation of biodiversity, but unfortunately they are almost always directed to a small subset of species. You may find organizations seeking to protect sea turtles, tigers, eagles or giant pandas, but can you think of anyone wanting to protect beetles? Most preservation programs target large and charismatic creatures, such as mammals, birds and flowering plants, while smaller and not-so-cute organisms remain neglected. And this is not only true in environments that included non-biologist people, but in all fields of research. And more than only leading to a bias in the protection of ecosystems, this preference leads to thousands of understudied species that could bring biotechnological revolutions to humandkind.
In an interesting study published this week in Nature’s Scientific Reports (see reference below), Troudet et al. analyzed the taxonomic bias in biodiversity data by comparing the occurrence of data on several taxonomic groups to those groups’ diversity. The conclusions are astonishing, although not that much surprising. The most charismatic groups, such as birds, are, one could say, overstudied, with an excess of records, while other, such as insects, are highly understudied. While birds have about 200 million occurences above the ideal record, insects have about 200 million below the ideal number. And the situation does not seem to have improved very much along the years.
The bias in interest is clear. The vertical line indicates the “ideal” number of occurrences of each group. A green bar indicates an excess of occurrences, while a red bar indicates a lack of occurrences. Birds and Insects are on the opposite extremes, but certainly the insect bias is much worse. Figure extracted from Troudet et al. (2017).***
Aditionally, the study concluded that the main reason for such disparity is simply societal preference, i.e., the most studied groups are the most loved ones by people in general. The issue is really a simple matter of charisma and has little to do with scientific or viability reasons.
The only way to change this scenario is if we find a way to raise awareness and interest of the general public on the less charismatic groups. We must make them interesting to the lay audience in order to receive their support and increase the number of future biologists that will choose to work with these neglected but very important creatures.
If you are digging through the sand at the bottom of the clear tropical waters around Indonesia and the Philippines, you may end up finding a colorful little creature, the hummingbird bobtail squid, Euprymna berryi, also known as Berry’s bobtail squid.
A beautiful specimen photographed in East Timor. Photo by Nick Hobgood.*
Measuring about 3 cm if male or 5 cm if female, the humminbird bobtail squid is actually more closely related to cuttlefish than to true squids. Its body has a translucent skin marked by many black chromatophores, and to the human eye the animal seems to have a color pattern formed by a blend of black, electric blue and green or purple dots.
During the day, the hummingbid bobtail squid remains most of the time buried in the sand, coming out at night to capture small crustaceans, which it hunts using a bioluminescent organ in its gill cavity.
In some areas around its distribution, the hummingbid bobtail squid is captured and sold in small fisheries, but as the data on the distribution and population dynamics of this species are very poorly known, there is no way to say whether it is vulnerable or endangered in any way. As a result, it is listed as Data Deficient in the IUCN Red List.
Who says beetles cannot be cute? Take a look at those guys:
They are eating a piece of banana. Photo by Wikimedia user Evanherk.*
These little fellows are beetles of the species Pachnoda marginata, commonly known as sun beetle or taxi cab beetle. Native from Africa, they reach up to 30 mm as adults and 60 mm as larvae and are one of the most common beetles raised as pets.
An adult with the wings exposed, about to fly. Photo by Wikimedia user Drägüs.*
The sun beetle has nine subspecies, each with a particular color pattern. The most well known subspecies is Pachnoda marginata peregrina and is the one shown in the photos above.
Since the sun beetle is easy to keep in the lab, it has been eventually used in scientific studies, especially some related to the neurology of the olphactory receptors.
– – –
References:
Larsson, M. C., Stensmyr, M.. C., Bice, S. B., & Hansson, B. S. (2003). Attractiveness of Fruit and Flower Odorants Detected by Olfactory Receptor Neurons in the Fruit Chafer Pachnoda marginata Journal of Chemical Ecology, 29 (5), 1253-1268 DOI: 10.1023/A:1023893926038
Stensmyr, Marcus C., Larsson, Mattias C., Bice, Shannon, & Hansson, Bill S. (2001). Detection of fruit- and flower-emitted volatiles by olfactory receptor neurons in the polyphagous fruit chafer Pachnoda marginata (Coleoptera: Cetoniinae) Journal of Comparative Physiology A, 187 (7), 509-519
Wikipedia. Pachnoda marginata. Availabe at: < https://en.wikipedia.org/wiki/Pachnoda_marginata >. Access on September 8, 2016.
While looking for flatfish you may eventually find one with some grotesque growth on the body, like the one in the picture below:
A xenoma caused by Glugea stephani on a flatfish Limanda limanda. Photo by Hans Hillewaert.*
This sort of tumor is called xenoma and, in flatfish, is caused by a microscopical and parasitic fungus named Glugea stephani, or the flounder glugea.
The flounder glugea is part of a group of fungi called Microsporidia that until recently were classified as protists. They are unicellular and parasite other organisms, especially crustaceans and fish.
Once inside a flatfish, the flounder glugea enters an intestinal cell and starts to develop. They induce the host cell to increase in size and may give rise to the xenomas, which are the most extreme stage in the development of the disease. The proliferating and active stage of the glugea are free in the cytoplasm of the host cell, but they may change into a spore-like form called sporoblast that remains inside a vacuole.
Image of electron microscopy of an intestinal cell of winter flounder (Pseudopleuronectes americanus) infected by flounder glugea (Glugea stephani). The S indicates sporoblasts inside the vacuole (SV) and the P the proliferating organisms inside the host cytoplasm (H). Image extracted from Takvorian & Cali (1983).
Fortunately most infections are mild and do not compromise the fish health, at least not very much…
– – –
References:
Takvorian, P. M.; Cali, A. (1983). Appendages associated with Glugea stephani, a microscporidian found in flounder. Journal of Protozoology, 30(2): 251-256.
Wikipedia. Xenoma. Available at: < https://en.wikipedia.org/wiki/Xenoma >. Access on September 17, 2016.
If you are walking through a forest in Europe you may find the bark of some trees covered by a thin rosy or orange crust. Commonly known as rosy crust, its scientific name is Peniophora incarnata.
Rosy crust growing on a dead branch. Photo by Jerzy Opioła.*
As with most fungi, the rosy crust is saprobic, i.e., it feeds on dead material, in this case dead wood, so that it is more commonly found attached to dead branches. It affects a variety of plant species, especially flowering plants, but may eventually grow on pine trees.
Sometimes considered a pest because of its ability to rotten wood, the rosy crust has also some interesting benefits. It has shown to have antimicrobial activity, being a potential source for the production of antibiotics, and is also able to degrade some carcinogenic products used to treat wood, such as polycyclic aromatic hydrocarbons.
Lee, H., Yun, S., Jang, S., Kim, G., & Kim, J. (2015). Bioremediation of Polycyclic Aromatic Hydrocarbons in Creosote-Contaminated Soil by Peniophora incarnata KUC8836 Bioremediation Journal, 19 (1), 1-8 DOI: 10.1080/10889868.2014.939136
Suay, I., Arenal, F,, Asensio, F. J., Basilio, A., Cabello, M. A., Díez, M. T., García, J. B., González del Val, A., Gorrochategui, J., Hernández, P., Peláez, F., & Vicente, M. F. (2000). Screening of basidiomycetes for antimicrobial activities Antonie van Leeuwenhoek, 78 (2), 129-140 DOI: 10.1023/A:1026552024021
Earthling Nature 