Stefan F. Wirth

I am a #biologist, #acarologist (my research area), entomologist and #evolutionary biologist. Also nature #photographer and nature and #macro #filmmaker. I am interested in all aspects of biology, and I also have a great weakness for astronomy and perform pictorial arts. Here you can see a mite of the genus #Balaustium (Erythraeidae), but my research is on mites of the #Histiostomatidae (Astigmata). Both Acariformes. I only have this one Twitter profile. © Stefan F. Wirth 2023

Regarding an #extinct, newly described #species of toothed #whale from the late #Miocene in present-day Peru, which is distinguished by unique #cranialfeatures. Bilateral symmetry is the most significant #evolutionaryinnovation (#apomorphy) of the #Bilateria. It facilitated a substantial radiation of species within both the Protostomia and Deuterostomia. Such #radiation is invariably accompanied by the formation of #ecologicalniches, leading to the evolution of #specific #adaptations to particular environmental conditions. #Asymmetries have #evolved across a wide variety of organismal groups, enabling them to adopt unconventional lifestyles. Examples include flatfish (#Pleuronectiformes) and, the focus here, whales. In connection with their fully #aquatic existence and the necessity for social #communication and orientation within this environment, sound-producing organs have evolved in the forehead region of whales. In toothed whales, these are associated with cranial asymmetries, which are particularly pronounced in #spermwhales (#Physeteroidea). Their skulls exhibit a leftward shift of the right #facialbones, including the #premaxilla and #nasalbone, along with the development of a cavity in the supracranial region that houses the whale’s #foreheadorgans. A. Benites-Palomino et al. (2026) described a new, extinct species of dwarf sperm whale from the Upper Miocene #PiscoFormation in #Peru. In #Scaphokogia #huachafo, the cranial asymmetry is exceptionally well-developed. The authors do not interpret this as an evolutionary intermediate stage on the stem lineage leading to modern sperm whales, but rather as a very distinct unique specialization, one that points to a #benthic (bottom-dwelling) #lifestyle characterized by increased ventral #neckflexibility. This represents the most extreme morphological cranial adaptation known among cetaceans, and, researchers suspect, possibly even among all mammals. © #StefanFWirth, November 2026, Berlin Please support my science communication—it is much needed: ko-fi.com/sfwirth Reference: A. Benites-Palomino et al. (2026): doi.org/10.1038/s42003-026-1… #Figure: Original figure from the paper cited above: #Holotype #skull of Scaphokogia huachafo: MUSM 972 in dorsal (a–c), right lateral (d–f), and ventral (g–i) views, shown as the specimen (a, d, g), schematic drawings (b, e, h), and segmented 3D surface reconstructions (c, f, i). Dotted red lines indicate the main cranial axis. Creative Commons Attribution 4.0 International License, creativecommons.org/licenses…

Why do #monkeys #ride on #pigs or cuddle with #dogs? In a 2026 study, researchers explored the #evolutionary #origins of the inclination toward keeping #pets in #humans. When animals interact with other species without an immediate survival advantage for either, it does not yet constitute "#petkeeping", but it may represent a phenomenon that touches upon the foundations that led humans to #domesticate #animals. To label such interactions as "pet-keeping" simply because one species derives pleasure or comfort from close physical contact with an unrelated species would be an act of #anthropomorphism; domestication is a far more complex process. Nevertheless, allowing a dog to groom you or using a pig as a mount requires more than just a reduced fear of other species. There must be a mutual #willingness or at least a willingness on one side and a #tolerance on the other side, both species involved must be prepared to invest their precious time in activities unrelated to reproduction, rearing offspring, or securing food. Both sides must perceive at least some kind of benefit in the interaction; joy, variety, a sense of security, or even cross-species #empathy can serve as #drivingforces. Yet, that alone is not enough. How, after all, can one animal convey to another that coming together might be pleasant, and therefore at least some kind of advantageous, for both parties? Through #communication, of course, specifically, #interspecies communication. This implies that only animals capable of understanding one another can socialize in this way, for instance, because they live under comparable social conditions and employ similar modes of communication. C. C. Grueter et al. (2026) investigated the evolutionary origins of human pet-keeping through a multimodal methodological approach. They employed systematic literature reviews, #expertconsultations in the field of #primatology, and digital and #socialmedia mining to gather data, or, in some cases, to transform raw information into data suitable for scientific analysis. Furthermore, a quantitative and phylogenetic analysis was conducted, in which the identified traits were mapped onto an existing #phylogenetictree. Through this, the researchers were able to reconstruct that the behavior of interacting with other species, in the manner described above, is by no means randomly distributed; rather, it is #deeplyrooted in the phylogenetic tree of primates. The #cognitive abilities and requirements for high social intelligence, the capacity for empathy, #curiosity, and a pronounced need for physical contact and social bonding, even across species boundaries, were already present in the ancestors of humans. © #StefanFWirth, November 2026, Berlin please support my science communication efforts: ko-fi.com/sfwirth reference: C. C. Grueter et al. (2026): doi.org/10.1007/s10329-026-0… #figure: original legend and figure by the authors mentioned above: Examples of affiliative interspecific interactions involving non-human primates. a Adult female white-faced capuchin (Cebus imitator) monkey grooming an adult female black-handed spider monkey (Ateles geoffroyi) in Santa Rosa, Costa Rica; photo by Nicholas Chapoy. b Capped langur (Trachypithecus pileatus) grooming a Phayre's leaf monkey (Trachypithecus phayrei) in Satchari National Park, Bangladesh; photo by Sabit Hasan. And further examples more, see original open access paper. By researchers above, 2026, CC BY 4.0, creativecommons.org/licenses…

Global #humanpopulation #growth has negative consequences for the #environment, and, by extension, for #biodiversity, because humans are no longer subject to the environment but instead compete with it. But what happens when human population density #decreases? The result may come as a surprise: this, too, can have an #adverseimpact on the environment and its biodiversity. While #global #populationdensity is increasing, it is not distributed evenly. In many places, the opposite is occurring, a decline in population density, particularly in #ruralregions. This often happens because people #migrate to #largecities, where earning an income is easier, or because natural areas have been placed under protection, rendering them unavailable for #agriculturaluse. But what are the environmental and biodiversity-related impacts of rewilding formerly agricultural land? The outcome can vary depending on local conditions. Biodiversity may increase, but it can also decline, specifically in areas where #speciesdiversity has #evolved over long periods alongside human presence and has thus become dependent on #humanshaped #landscapes. Agricultural land can serve as a habitat for species that rely precisely on such conditions. Similarly, in forests traditionally managed for timber, one may find species that depend on open, sparsely wooded areas. This is also particularly true for urban landscapes, such as parks, vacant lots, or cemeteries, all of which are environments constantly maintained by humans. If #ecologicaldiversity is actively and artificially sustained, urban biodiversity remains high; however, if a park is left to go wild without any management, biodiversity tends to decrease. As an example, consider Berlin and its green spaces: they are often rich in species, even though this densely populated metropolis contains very few natural areas that are not frequently overrun by crowds of people (my photos attached). In her news feature for the journal Nature, E. Marris (2026) explores the topic: "When humans disappear, biodiversity takes a surprising turn." Among other things, the author refers to a study by #Japanese researchers K. Uchida et al. (2025), who examined thousands of species across more than 150 forested, agricultural, and urban areas in Japan. The researchers observed a decline in species in locations affected by a drop in human population density. These findings #contradict the widely held thesis that fewer humans always equate to greater biodiversity. © #StefanFWirth, November 2026, Berlin Please support my science communication efforts—your help is needed: ko-fi.com/sfwirth References: E. Marris (2026): nature.com/articles/d41586-0… K. Uchida et al. (2025): ideas.repec.org/a/nat/natsus… #Photos: © Stefan F. Wirth; people in the #Berlin district of Friedrichshain after the "Carnival of Cultures" parade, May 2026

Please watch and like my latest #YouTube #video about the meadow #tick #Dermacentor #reticulatus and its #behaviors: youtu.be/7e2hOnkNAFA?is=pcb9… The #meadowtick originally favored regions with warmer #temperatures. However, due to #globalwarming, it has since managed to establish itself permanently in temperate #CentralEurope. There are "hotspots" in various parts of #Germany, such as #Berlin or the Saarland. It is important to remove these ticks from pets as quickly as possible, as they can, for instance, transmit canine babesiosis. In my video, I present this animal accompanied by atmospheric, almost gentle piano music, obviously not to focus primarily on its #threatening nature, but rather to highlight that it is a #remarkable #arachnid, possessing a complex range of behaviors and highly efficient #sensoryorgans. The video shows not only how the tick #moves and #navigates its environment, but also the distinct #grace, almost #elegance, with which it does so. The tick had clearly already taken a blood meal before I removed it from my dog. It then chose none other than me as its next #host, making a concerted effort to get as close as possible. As it moves, it sometimes does so on seven #legs, while one of its front legs remains extended into the air; this allows the #Hallersorgan located there to detect and pinpoint my #sweat, #bodyheat, and #respiration. Like many other arthropods, the tick also needs to #groom itself; it meticulously #cleans the area around the Haller’s organs on its #frontlegs using the adjacent legs. Once a tick has reached an #elevatedposition that offers a good vantage point for detecting a host, it frequently extends both of its front legs upward, whether it is moving or at rest, often performing "#waving" motions while #walking. © #StefanFWirth, November 2026, Berlin #Photos: #Videoframes and video cover picture as #collage, based on my #macro #footage from September, edited November 2026, #Berlin, © Stefan F. Wirth

In early November 2026, the second phase of #NASA’s three-part #CHAPEA (Crew Health and Performance Exploration Analog) mission series concluded. These missions serve as #simulations to test conditions for a potential future #crewedbase on #Mars. The tests take place within "Mars #DuneAlpha," a #habitat spanning approximately 160 square meters, located at NASA’s Lyndon B. Johnson #SpaceCenter in Houston, Texas. The participants' daily routine includes conducting #scientificexperiments, #cultivatingplants (using hydroponics), and performing #maintenancetasks. The program also features "outside" activities in an area that simulates the Martian landscape; for these, the participants must exit the base through an airlock while wearing pressurized #spacesuits. A crewed mission to Mars, including the establishment of a base there, entails a wide range of requirements. Beyond the months-long #journey, the low #gravity,to which humans would be permanently exposed, also presents obstacles to the success of such a mission. Yet, these factors were not part of the CHAPEA simulations conducted to date. Those simulations focused primarily on how a crew functions as a #team when living in long-term #isolation, left to their own devices on the surface of an alien planet. This also included #communicationdelays of up to 22 minutes, which roughly corresponds to the time it takes for a signal to travel between Mars and Earth. The results of the second Mars simulation experiment, which lasted 378 days, will be analyzed in the period following the mission. The third and final experiment in this series is already in preparation and is scheduled to begin no earlier than August 2027. © #StefanFWirth, November 2026 please support my science communication efforts ko-fi.com/sfwirth references: NASA: nasa.gov/humans-in-space/cha… The Straits Times (2026): straitstimes.com/world/crew-… #photo: The CHAPEA crews will live and work in a 1,700-square-foot, 3D-#printedhabitat located at NASA’s Johnson Space Center. The habitat includes four individual #livingquarters for the volunteer #crew. PHOTO DATE: 11-30-22 LOCATION: Bldg. 220 - CHAPEA SUBJECT: Photography of the Crew Health and Performance Exploration Analog (CHAPEA) facility PHOTOGRAPHER: BILL STAFFORD public domain, nasa.gov/multimedia/guidelin…

Interesting new findings about the #vocalcontrol in #crows. See attached link, it's about the effects from changing/#switching between different #types of #vocalizations. © #StefanFWirth, November 2026, Berlin Illustration; © Stefan F. Wirth, AI assisted artistic illustration, based on my hand-drawn sketches, manually edited, Carrion Crow and its brain, responsible for cognition and vocal control in birds.

When #newspecies, such as #Acer #wenshanense (#Sapindaceae) in this instance, are classified as "critically #endangered," or, as the authors J. S. Chen et al. (2026) term them, "Plant Species with Extremely Small Populations" (#PSESP), it clearly illustrates the #challenges #taxonomists face. #Biodiversity research, which is particularly vital in the context of #globalwarming, as it allows us to understand the nature of the environment we aim to protect and, consequently, how to protect it effectively, frequently leads to the discovery of species that are, for all practical purposes, #nearlyextinct. In such cases, one might almost say that we have arrived too late. The inherent #dynamics of our biodiversity are, even in the absence of climate-related threats, already highly volatile. As a result, it is often unavoidable that #environmentalconservation models are based primarily on more common and well-documented species and their ecological contexts. Acer wenshanense by the way is (so far) represented by only one single large #tree in its Chinese #typelocality. © #StefanFWirth, November 2026, Berlin

A #newlydescribed #species of the family #Thismiaceae (known as "fairy lanterns") belonging to the genus #Oxygyne has been discovered in #SoutheastAsia, effectively bridging the #geographicalgap in the genus's distribution between #Africa and #Japan. From an #evolutionary perspective, the Thismiaceae are highly #specialized plants that have completely lost their chlorophyll, and, consequently, their functional foliage. They inhabit the dimly lit #forestfloor of tropical and subtropical #primevalforests, having adapted to these unique environmental conditions through a form of #parasitic heterotrophy. They derive their nutrients from fungi present in the soil, typically #mycorrhizalfungi, such as those in the phylum #Glomeromycota, which exist in symbiotic relationships with trees. Thismiaceae generally remain inconspicuous within the forest floor; only during their flowering period does a distinct, often bizarrely shaped and vividly colored #inflorescence emerge from the ground, a phenomenon that gave rise to the term "fairy lanterns" in traditional folklore. Evolutionary biologists hypothesize that the ancestral lineage of the Thismiaceae was already symbiotically associated with fungi and inhabited dark, soil-rich environments, initially through conventional mycorrhizal associations. Over time, the plants’ existing chloroplasts were entirely lost, and the original #symbiosis #evolved into #parasitism. Researchers N. Tanaka et al. (2026) have described a new species, Oxygyne #myanmarensis, from Myanmar (Southeast Asia). The discovery of a representative of this genus in Southeast Asia provides clues regarding a former distribution range that spanned the #EurasianAfrican #continent. This helps researchers better understand the evolutionary history of the genus, as well as that of the Thismiaceae. The current fragmentation of the distribution range can be explained by historical #climatechanges (such as ice ages or the aridification of intervening regions). In terms of floral morphology, the new species suggests a closer relationship to Japanese species. © #StefanFWirth, November 2026, Berlin Reference: N. Tanaka et al. (2026): doi.org/10.11646/phytotaxa.7…

A previously unknown #cellorganelle has been #discovered in a marine #mollusk. #Aplacophora are a group of shell-less, worm-like mollusks; it has long been debated whether they constitute a #monophyletic #taxon (a #clade). But recent molecular genetic data suggest that they do indeed form a monophyletic group, which serves as the sister taxon to the #chitons (#Polyplacophora). The species #Chaetoderma #shenloong, discovered only in 2024, is the only known representative of the Aplacophora found in a #chemosynthetic #environment. The animal lives at a depth of approximately 1,385 meters at the "Haima" and "Jiaolong Ridge" #methaneseeps in the South China Sea. It is notably large compared to other #species within its taxon, which are often only a few millimeters in size; C. shenloong, by contrast, reaches a length of about 15.4 cm, making it a giant by comparison. There are other remarkable features as well. Researchers Y. Li et al. (2026) discovered a previously unknown cell #organelle in this species that serves to house symbiotic, #sulfuroxidizing #bacteria. The mollusk, which lives about 40 cm below the sediment surface in black, oxygen-free (#anoxic) mud, has lost large portions of its #digestivetract. Only the #midgutgland remained, and it has become significantly enlarged. Within its cells, the authors identified #spherical, #multilamellar #compartments containing the chemosynthetic bacteria. The researchers have named this novel type of cell organelle "#dracosphera." © #StefanFWirth, October 2026, Berlin Please support my science communication efforts: ko-fi.com/sfwirth Reference: Y. Li et al. (2026): doi.org/10.1038/s41467-026-7…

A recent #research study has shown that #spiders experience different #sleepphases, including an #REM (rapid eye movement) phase, the same type observed in humans. #Sleep is a phenomenon found across a wide range of animal organisms. It serves to provide the #nervoussystem with a period of rest. During sleep, an animal’s metabolism and energy expenditure are reduced, allowing it to conserve energy reserves; upon waking, the animal can then draw on these preserved resources for activities such as foraging, reproduction, and daily survival. However, sleep is not entirely devoid of energy consumption. Movements of the limbs, eyes, and facial muscles can occur, not uniformly throughout the entire sleep period, but rather within specific, distinct sleep phases. One particularly notable sleep phase is #REMsleep, often referred to as "dream sleep." In humans, this phase is characterized by intense #dreaming; these dreams are typically coherent, emotionally charged, and frequently accompanied by motor activity. Upon waking, humans are often able to recall dreams that occurred during this stage. Specific motor activities during REM sleep include movements of the eyes and the body's musculature. While various sleep phases, including the REM phase, have been documented in nearly all #mammalian #species, the nature of sleep in other groups, such as arthropods, remains an open question. Do they sleep at all? Existing research on this subject is still quite scarce. Researchers N. Geiger et al. (2026) investigated the sleep behavior of the Australian #jumpingspider #Portia #fimbriata (Salticidae). The results demonstrated that the spider does indeed sleep and exhibits at least two distinct sleep phases, one of which is functionally analogous to the REM (rapid eye movement) phase observed in mammals. During this stage, the spider displayed noticeable #eyemovements and body muscular activity (see attached figure). While it was not possible to measure brain waves, the researchers analyzed high-resolution #videofootage and conducted experiments to confirm that the spider was truly sleeping, rather than merely resting in an immobile state. To this end, a sound was produced to rouse the spider from its sleep; the longer the reaction time, the higher the probability that the animal had been asleep. In a broader context, sleep has evolved independently multiple times across various animal groups with vastly different body plans. Nevertheless, the authors used their findings regarding a sleeping spider as a basis to explore whether there might be fundamental aspects of sleep and dreaming that originated in early Bilateria and have been preserved, in some form, across all subsequent animal lineages. © #StefanFWirth, October 2026, Berlin Please support my science communication efforts: ko-fi.com/sfwirth Reference: N. Geiger et al. (2026): doi.org/10.1073/pnas.2618030… Figure: N. Geiger et al. (2026), licensed under creativecommons.org/licenses…

On October 28, 2026, the #MontereyBayAquarium #ResearchInstitute (#MBARI) published spectacular 4K #videofootage of the deep-sea fish #Macropinna #microstoma (#Opisthoproctidae) off the coast of #California, using their new #researchvessel, the R/V David Packard, and the remotely operated vehicle (#ROV) Doc Ricketts Measuring approximately 11 cm in length, this #species, which has a remarkably small mouth, is a predator that feeds on zooplankton and parts of #jellyfish. Seemingly in the context of consuming jellyfish, the fish has evolved striking and unusual #adaptations around its #eyes, likely to protect them from the jellyfish's #stingingcells. Its eyes are situated beneath a transparent, fluid-filled #dome that #covers a large portion of each side of its head. This fluid-filled space serves as an additional layer of #protection for the eyes. The species is distributed across the #NorthPacific, ranging from the Bering Strait and Japan as far south as Baja California, Mexico. It inhabits the mesopelagic zone, at depths between 16 and 1,015 meters. The research findings from this recent mission have yet to be fully analyzed. In an earlier paper published in the journal Current Biology, authors S. Johnson and S. H. D. Haddock (2022) provide a more detailed introduction of this species and its genus. © #StefanFWirth, October 2026, Berlin Please support my science communication efforts: ko-fi.com/sfwirth Further reading: S. Johnson & S. H. D. Haddock Haddock (2022): doi.org/10.1016/j.cub.2022.0… Phys.org on X (2026): teapawt.net/physorg_com/status/211… Photo: #Illustration of #barreleye (Macropinna microstoma), cropped and upscaled from Fig 6 of Poulsen et al. (2016). Licensed under creativecommons.org/licenses…

The #fish #Oligosarcus #bolivianus (#Characidae), sometimes referred to as the "#BolivianToothy", is endemic to the border region between #Argentina and #Bolivia, specifically within the upper Río Bermejo drainage and the #Paraguay River basin. Reaching a length of approximately 15 cm, the species exhibits specialized evolutionary adaptations in its oral morphology and dentition for #preying on other fish. In terms of #hunting strategy, it functions primarily as an #ambushpredator. According to the #IUCN Red List, the species is classified as "Least Concern." © #StefanFWirth, October 2026, Berlin Further reading on the phylogeny of the family Characidae (Teleostei: Characiformes): J. M. Mirande (2010): doi.org/10.1590/S1679-622520…