Horseshoe crabs, really relatives of spiders, scorpions


This 3 March 2019 video from the USA says about itself:

It’s Cameraman Tim’s debut as a field correspondent! Tim travels to Cape Cod, Massachusetts to investigate the annual Horseshoe Crab invasion!

From the University of Wisconsin-Madison in the USA:

Horseshoe crabs are really relatives of spiders, scorpions

March 8, 2019

Summary: By analyzing troves of genetic data and considering a vast number of possible ways to examine it, scientists now have a high degree of confidence that horseshoe crabs do indeed belong within the arachnids.

Blue-blooded and armored with 10 spindly legs, horseshoe crabs have perhaps always seemed a bit out of place.

First thought to be closely related to crabs, lobsters and other crustaceans, in 1881 evolutionary biologist E. Ray Lankester placed them solidly in a group more similar to spiders and scorpions. Horseshoe crabs have since been thought to be ancestors of the arachnids, but molecular sequence data have always been sparse enough to cast doubt.

University of Wisconsin-Madison evolutionary biologists Jesús Ballesteros and Prashant Sharma hope, then, that their recent study published in the journal Systematic Biology helps firmly plant ancient horseshoe crabs within the arachnid family tree.

By analyzing troves of genetic data and considering a vast number of possible ways to examine it, the scientists now have a high degree of confidence that horseshoe crabs do indeed belong within the arachnids.

“By showing that horseshoe crabs are part of the arachnid radiation, instead of a lineage closely related to but independent of arachnids, all previous hypotheses on the evolution of arachnids need to be revised,” says Ballesteros, a postdoctoral researcher in Sharma’s lab. “It’s a major shift in our understanding of arthropod evolution.”

Arthropods are often considered the most successful animals on the planet since they occupy land, water and sky and include more than a million species. This grouping includes insects, crustaceans and arachnids.

Horseshoe crabs have been challenging to classify within the arthropods because analysis of the animals’ genome has repeatedly shown them to be related to arachnids like spiders, scorpions, mites, ticks and lesser-known creatures such as vinegaroons. Yet, “scientists assumed it was an error, that there was a problem with the data,” says Ballesteros.

Moreover, horseshoe crabs possess a mix of physical characteristics observed among a variety of arthropods. They are hard-shelled like crabs but are the only marine animals known to breathe with book gills, which resemble the book lungs spiders and scorpions use to survive on land.

Only four species of horseshoe crabs are alive today, but the group first appeared in the fossil record about 450 million years ago, together with mysterious, extinct lineages like sea scorpions. These living fossils have survived major mass extinction events and today their blood is used by the biomedical industry to test for bacterial contamination.

Age is just one of the problems inherent in tracing their evolution, say Ballesteros and Sharma, since searching back through time to find a common ancestor is not easy to accomplish. And evidence from the fossil record and genetics indicates evolution happened quickly among these groups of animals, convoluting their relationships to one another.

“One of the most challenging aspects of building the tree of life is differentiating old radiations, these ancient bursts of speciation,” says Sharma, a professor of integrative biology. “It is difficult to resolve without large amounts of genetic data.”

Even then, genetic comparisons become tricky when looking at the histories of genes that can either unite or separate species. Some genetic changes can be misleading, suggesting relationships where none exist or dismissing connections that do. This is owed to phenomena such as incomplete lineage sorting or lateral gene transfer, by which assortments of genes aren’t cleanly made across the evolution of species.

Ballesteros tested the complicated relationships between the trickiest genes by comparing the complete genomes of three out of the four living horseshoe crab species against the genome sequences of 50 other arthropod species, including water fleas, centipedes and harvestmen.

Using a complex set of matrices, taking care not to introduce biases in his analysis, he painstakingly teased the data apart. Still, no matter which way Ballesteros conducted his analysis, he found horseshoe crabs nested within the arachnid family tree.

He says his approach serves as a cautionary tale to other evolutionary biologists who may be inclined to cherry-pick the data that seem most reliable, or to toss out data that don’t seem to fit. Researchers could, for example, “force” their data to place horseshoe crabs among crustaceans, says Sharma, but it wouldn’t be accurate. The research team tried this and found hundreds of genes supporting incorrect trees.

Ballesteros encourages others to subject their evolutionary data to this kind of rigorous methodology, because “evolution is complicated.”

Why horseshoe crabs are water dwellers while other arachnids colonized land remains an open question. These animals belong to a group called Chelicerata, which also includes sea spiders. Sea spiders are marine arthropods like horseshoe crabs, but they are not arachnids.

“What the study concludes is that the conquest of the land by arachnids is more complex than a single tradition event,” says Ballesteros.

It’s possible the common ancestor of arachnids evolved in water and only groups like spiders and scorpions made it to land. Or, a common ancestor may have evolved on land and then horseshoe crabs recolonized the sea.

“The big question we are after is the history of terrestrialization,” says Sharma.

For Ballesteros, who is now studying the evolution of blindness in spiders living deep within caves in Israel, his motivations get to the heart of human nature itself.

“I get to look with childish curiosity and ask: ‘How did all this diversity come to be?'” he says. “It’s incredible what exists, and I never thought I would have the privilege to be able to do this.”

The study was funded by the M. Guyer postdoctoral fellowship and supported by National Science Foundation grant IOS-1552610.

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New tarantula species discovery in Angola


This 9 February 2019 video says about itself:

Let’s call it “The Mega Horned Baboon Tarantula” – what do you think?
Ceratogyrus attonitifer is a new species described by the arachnologist Ian Engelbrecht. This baboon tarantula is native to the country of Angola and has an astonishing horn – something we’ve never seen before, covering almost the entire opisthosoma of the baboon tarantula spider.

It’s remarkable – watch the video, enjoy its beauty and let’s hope for more pictures and videos of this new baboon tarantula species soon!

From ScienceDaily:

New tarantula species from Angola distinct with a one-of-a-kind ‘horn’ on its back

February 12, 2019

A new to science species of tarantula with a peculiar horn-like protuberance sticking out of its back was recently identified from Angola, a largely underexplored country located at the intersection of several Afrotropical ecoregions.

Collected as part of the National Geographic Okavango Wilderness Project, which aims to uncover the undersampled biodiversity in the entire Okavango catchment of Angola, Namibia and Botswana, thereby paving the way for sustainable conservation in the area, the new arachnid is described in a paper published in the open-access journal African Invertebrates by the team of Drs John Midgley and Ian Engelbrecht.

Although the new spider (Ceratogyrus attonitifer sp.n.) belongs to a group known as horned baboon spiders, the peculiar protuberance is not present in all of these species. Moreover, in the other species — where it is — the structure is completely sclerotised, whereas the Angolan specimens demonstrate a soft and characteristically longer ‘horn’. The function of the curious structure remains unknown.

The new tarantula’s extraordinary morphology has also prompted its species name: C. attonitifer, which is derived from the Latin root attonit- (“astonishment” or “fascination”), and the suffix -fer (“bearer of” or “carrier”). It refers to the astonishment of the authors upon the discovery of the remarkable species.

“No other spider in the world possesses a similar foveal protuberance,” comment the authors of the paper.

During a series of surveys between 2015 and 2016, the researchers collected several female specimens from the miombo forests of central Angola. To find them, the team would normally spend the day locating burrows, often hidden among grass tufts, but sometimes found in open sand, and excavate specimens during the night. Interestingly, whenever the researchers placed an object in the burrow, the spiders were quick and eager to attack it.

The indigenous people in the region provided additional information about the biology and lifestyle of the baboon spider. While undescribed and unknown to the experts until very recently, the arachnid has long been going by the name “chandachuly” among the local tribes. Thanks to their reports, information about the animal’s behaviour could also be noted. The tarantula tends to prey on insects and the females can be seen enlarging already existing burrows rather than digging their own. Also, the venom of the newly described species is said to not be dangerous to humans, even though there have been some fatalities caused by infected bites gone untreated due to poor medical access.

In conclusion, the researchers note that the discovery of the novel baboon spider from Angola does not only extend substantially the known distributional range of the genus, but can also serve as further evidence of the hugely unreported endemic fauna of the country:

“The general paucity of biodiversity data for Angola is clearly illustrated by this example with theraphosid spiders, highlighting the importance of collecting specimens in biodiversity frontiers.”

Apart from the described species, the survey produced specimens of two other potentially new to science species and range expansions for other genera. However, the available material is so far insufficient to formally diagnose and describe them.

Spiders dating, dangerous or delicious?


This 11 February 2019 video from the Natural History Museum in London, England says about itself:

What are the secrets of spider dating? | Natural History Museum

For some spiders, choosing the wrong mate can be deadly. Jan Beccaloni, Curator of Arachnida and Myriapoda, explains some of the tactics male spiders use to avoid becoming their mate’s next meal.

This spider slingshots itself at extreme speeds to catch prey. The Peruvian spider and its web go flying with 100 times the acceleration of a cheetah. By Emily Conover, 10:19am, March 6, 2019.

Spiders of Spain, new study


This 9 July 2015 video shows a jumping spider on a garden table in Gaucin, Southern Spain.

From the University of Barcelona:

Broading the biodiversity catalogue of spider populations in the Iberian Peninsula

Iberian arachnology: An area to be explored

December 18, 2018

Summary: The biodiversity catalogue of the Iberian Peninsula spiders is now adding the discovery of a dozen new species — from seven different families — that are mainly found in edaphic environments (soil), according to a new article.

The new study, covering the largest study area on this animal group in peninsular territory, is now published in the Biodiversity Data Journal. Other participants in the study are the experts from the Experimental Station of Arid Zones (EEZA-CSIC) and the University of Helsinki (Finland).

A sampling of more than 20,000 spider samples

The scientific team has studied a total of 20,539 samples of different Iberian spider species -with 8,521 adult specimens corresponding to 190 genera, 39 families and 376 species- in the oak woodlands of National Parks in Aiguestortes i Estany de Sant Maurici, Ordesa i Mont Perdut, the Peaks of Europe, Monfragüe, Cabañeros and Sierra Nevada.

These forests with temperate climate -where arboreal species and deciduous trees are abundant- represent the most appropriate natural habitat “to study the biogeographic patterns of spiders at a peninsular scale”, says Professor Miquel Àngel Arnedo. “In a broader sense, oak woodlands are a few of the forest communities that are represented in all National Parks building up our study. These are natural habitats of interest regarding conservation, and show a high level of endemism and their evolutionary history is quite well known.”

Iberian arachnology: an area to be explored

The degree of knowledge on the geographic distribution of Iberian spiders is still very little compared to other Mediterranean countries. “The lack of tradition in natural history studies in the country and the reduced amount of admirers of arachnology could explain these differences”, says Arnedo, member of the Department of Evolutionary Biology, Ecology and Environmental Sciences of the Faculty of Biology and IRBio.

The research team has found eleven new spider species -so far more than 1,300 species were known in the peninsula and the Balearic Islands- apart from other twenty species whose taxonomic identification is still pending. According to the experts, some of the new species could be especially vulnerable to the environmental factors (in most of the cases, only one or a few individuals have been discovered in one geographical place or even one parcel).

Moreover, the experts add seven new spider species to the peninsular biological inventory -and three more in Spain- with the identification in the area of species such as Dictyna pusilla, Philodromus buchari, Pseudeuophrys nebrodensis, Euryopis flavomaculata, Titanoeca schineri, Dipoena torva and Sardinion blackwalli, some of them described in the scientific bibliography since the late 19th century. “None of these species can be considered as rare -notes Arnedo- since they had been identified in other places such as France, Portugal and Central Europe.”

“There are still many spider species to be found”, adds Arnedo. “These results show there is a lack of systematic samplings in the arachnological biodiversity in Spain and are a good example of the few things we know about our own fauna.”

Reconstructing the evolutionary history of peninsular spiders

The sampling technique for spider specimens in the natural environment has followed the standardized protocol COBRA. This methodology -applied in studies of terrestrial arthropod communities worldwide- enables researchers to create an inventory of the species in a specific area and brings data to extrapolate the amount and abundance of species that can live in a geographical area.

Moreover, the methodology based on content such as DNA barcoding -that is, the use of a short and standardized DNA fragment as the identifier of a species- is the innovating technique for applied comparative genetics to speed up the identification of species and improve the resolution of the analysis of biodiversity in this animal group. “This methodology enables developing high-resolution bioinformatic tools to help automatizing the classification and identification of species, even in populations of the same species in different places,” says Arnedo.

“For instance, young individuals cannot be classified as species through morphological criteria, which in many cases they only reach the family taxon. With the DNA barcoding we can categorize them under specific species. This technique also helps to identify different vital stages in the same species -even remains such as exuvia or overlayers, excrements or environmental DNA- which would be impossible to distinguish otherwise.

Knowing the natural heritage to protect biodiversity

Loss of natural habitat, invasive species, environmental pollution and global warming are threats that put the conservation of peninsular arachnological fauna in danger. Some spider species tolerate environmental perturbations better than others -these are generalist predators and adapt to changes- but other groups are more sensitive to environmental factors. In the future, samplings will need standardized protocols and wider taxonomical data with nuclear molecular markers, the morphological studies and ecological information as well to know about the evolutionary and biogeographic history of peninsular spiders to guarantee their conservation.

“Like the other organisms, spiders are submitted to variations in their environmental and biological environment. We are all in the same boat and with the same destination, the difference is that we are the in charge of this destiny”, concludes Professor Miquel Àngel Arnedo.

Spider mothers’ milk for babies


This 29 November 2018 video says about itself:

This small jumping spider is nursing her young with milk | Science News

Female Toxeus magnus spiders, native to tropical and subtropical areas in Asia, produce nutrient-rich milk to feed their young for weeks, even after the spiderlings begin to hunt on their own. Here, a 1-week-old juvenile nurses an area of its mother’s abdomen from which the milk is available.

Read more here.

From the Chinese Academy of Sciences Headquarters:

Mammal-like milk provisioning and parental care discovered in jumping spider

November 29, 2018

Summary: Researchers report milk provisioning in Toxeus magnus (Araneae: Salticidae), a jumping spider that mimics ants. Milk provisioning in T. magnus involves a specialized organ over an extended period, similar to mammalian lactation. The study demonstrated that mammal-like milk provisioning and parental care for sexually mature offspring have also evolved in invertebrates.

Lactation is the production and secretion of milk for the young and is a mammalian attribute. However, there have been few examples of milk provisioning in non-mammals.

In a study published in the journal Science on November 30, researchers at the Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences report milk provisioning in Toxeus magnus (Araneae: Salticidae), a jumping spider that mimics ants.

In a field study, researchers observed a jumping spider species whose breeding nest is composed of either several large individuals, with two or more adults, or one adult female and several juveniles.

“It’s a puzzling observation for a species assumed to be noncolonial. It’s possible that the jumping spider might provide either prolonged maternal care or delayed dispersal. We decided to test it,” said Dr. CHEN Zhanqi, the first author of the study.

The researchers assessed how offspring developed and behaved under maternal care both in laboratory conditions and in the field. No spiderlings were observed leaving the nest for foraging until they were 20 days old.

Closer observation revealed that the mother provided a seemingly nutritive fluid, hereafter called milk, to the offspring.

Milk provisioning in T. magnus involves a specialized organ over an extended period, similar to mammalian lactation. Observations under the microscope showed droplets leaking from the mother’s epigastric furrow where the spiderlings sucked milk.

The spiderlings ingest nutritious milk droplets secreted from the mother’s epigastric furrow until the subadult stage (around 40 days). If blocked from obtaining milk, the newly emerged spiders will stop development and die within 10 days, showing that milk is indispensable for offspring survival in the early stage.

Moreover, the researchers tested why parental care and milk provisioning were continued after 20 days when the spiderlings were able to forage for themselves.

The mother continued nest maintenance throughout, carrying out spiderlings’ exuviae and repairing nest damage. When receiving both maternal care and milk, 76% of the hatched offspring survived to adulthood (around 52 days).

Milk provisioning after 20 days did not affect adult survivorship, body size, sex ratio or development time, but the mother’s presence played a key role in assuring a high adult survival rate and normal body size. Thus, milk provisioning complemented their foraging in later stages.

Although the mother apparently treated all juveniles the same, only daughters were allowed to return to the breeding nest after sexual maturity. Adult sons were attacked if they tried to return. This may reduce inbreeding depression.

The findings show that in the jumping spider species, the mother invests much more than the male invests, predicting a female-biased sex ratio to be optimal for reproductive success with a polygamous mating system.

“Our findings demonstrate that mammal-like milk provisioning and parental care for sexually mature offspring have also evolved in invertebrates,” said Dr. CHEN. “We anticipate that our findings will encourage a reevaluation of the evolution of lactation and extended parental care and their occurrences across the animal kingdom.”

Also flies, beetles produce milk. Mammals not that unique: here.

Newly discovered wasp turns spiders into zombies


This video says about itself:

30 May 2017

The Ichneumonid wasp Zatypota albicoxa (Hymenoptera, Ichneumonidae, Polysphinctini) lays a single egg on the house spider Parasteatoda tepidariorum.

The video shoes the attack of the wasp and the paralyzing sting in the underside of the spider’s prosoma. As soon as the spider is paralyzed, the wasp rubbs frequently on the spider’s opisthosoma with its ovipositor-sting, the ovipositor-sheaths being bent upward. In between the wasp makes some injections into the spiders prosoma, searching the right place for the injections at the border of the sternum between the coxae. Thereafter the front of the opisthosoma is rubbed again with the sting and the abdomen tip.

Finally, the wasp slides the tip of its abdomen in the gap between the spider’s prosoma and opisthosoma. A small drop of liquid (glue) runs out of the abdomen tip, followed by the egg itself. The egg is not expelled by the ovipositor, but directly from the tip of the abdomen. Then the wasp retires her abdomen, goes some steps away from the spider, comes back once again and has a last look to its egg. Then she cleans her front legs and goes away.

The spider will awake within the next 40 minutes and will at first continue its normal life. Some days later, the larva will hatch from the egg. It will suck slightly on the spider’s abdomen, at first without much growing. Finally, shortly before the spider is killed by the wasp larva, it will make a special web for the pupation of the wasp larva. Then in two days the ichneumonid larva sucks all the fluid from the spider and spins its own cocoon within this web.

From the University of British Columbia in Canada:

Newly discovered wasp turns social spiders into zombies

November 27, 2018

It sounds like the plot of the world’s tiniest horror movie: deep in the Ecuadorian Amazon, a newly discovered species of wasp transforms a “social” spider into a zombie-like drone that abandons its colony to do the wasp’s bidding.

That’s the gruesome, real-life discovery by University of British Columbia researchers, who detail the first example of a manipulative relationship between a new Zatypota species wasp and a social Anelosimus eximius spider in a study published recently in Ecological Entomology.

“Wasps manipulating the behaviour of spiders has been observed before, but not at a level as complex as this,” said Philippe Fernandez-Fournier, lead author of the study and former master’s student at UBC’s department of zoology. “Not only is this wasp targeting a social species of spider but it’s making it leave its colony, which it rarely does.”

Fernandez-Fournier was in Ecuador studying different kinds of parasites that live in the nests of Anelosimus eximius spiders, one of only about 25 species of “social” spiders worldwide. They are notable for living together in large colonies, cooperating on prey capture, sharing parental duties and rarely straying from their basket-shaped nests.

When Fernandez-Fournier noticed that some of the spiders were infected with a parasitic larva and spotted them wandering a foot or two away from their colonies to spin enclosed webs of densely spun silk and bits of foliage, he was puzzled. “It was very odd because they don’t normally do that, so I started taking notes,” he said.

Intrigued, he carefully took a few of the structures, known as “cocoon webs” back to the laboratory to see what would emerge from the depths.

To his surprise, it was a wasp.

“These wasps are very elegant looking and graceful,” said Samantha Straus, co-author of the study and PhD student in UBC’s department of zoology. “But then they do the most brutal thing.”

Using data gathered in Ecuador for different projects between 2012 and 2017, the researchers began to piece together the life cycle of the wasp and its parasitic relationship to the spider.

What they found was equal parts fascinating and horrifying: after an adult female wasp lays an egg on the abdomen of a spider, the larva hatches and attaches itself to its hapless arachnid host. It then presumably feeds on the spider’s blood-like haemolymph, growing larger and slowly taking over its body. The now “zombified” spider exits the colony and spins a cocoon for the larva before patiently waiting to be killed and consumed. After feasting on the spider, the larva enters its protected cocoon, emerging fully formed nine to eleven days later.

In other similar instances of parasitism, wasps are known to target solitary species of spiders like orb weavers and manipulate them into behaviours that are within their normal repertoire.

“But this behaviour modification is so hardcore,” said Straus. “The wasp completely hijacks the spider’s behaviour and brain and makes it do something it would never do, like leave its nest and spinning a completely different structure. That’s very dangerous for these tiny spiders.”

It’s not known how the wasps do this, but scientists believe it may be caused by an injection of hormones that make the spider think it’s in a different life-stage or cause it to disperse from the colony.

“We think the wasps are targeting these social spiders because it provides a large, stable host colony and food source,” said Straus. “We also found that the larger the spider colony, the more likely it was that these wasps would target it.”

Straus, who now sports a tattoo of the wasp, will return to Ecuador to investigate whether the wasps return to the same spider colonies generation after generation and what evolutionary advantage that might present.

Meanwhile, the wasps will likely continue their starring role in the spiders’ worst nightmares.

Spider removes pine needle from web


In this 22 November 2018 video, a European garden spider removes a pine needle from its web.

The needle hinders the spider in finding out whether there is a prey in the web.

After the needle was gone, the spider repaired the web.

Ilse Cameron in the Netherlands made this video.