Bertia cambojiensis

In a new study from the <a href="https://www.uc.edu/">University of Cincinnati</a>, researchers have discovered that a type of brightly colored jumping spider is <a href="https://www.earth.com/news/dinosaurs-may-have-had-pops-of-color-like-modern-ducks/">color</a> blind. The study was focused on Saitis barbipes, a common jumping spider found in Europe and North Africa. 



The males of this species have a furry red crown and legs. They are known for performing elaborate courtship dances.



“We assumed they were using color for communication. But we didn’t know if their visual system even allowed them to see those colors,” said study co-first author David Outomuro.



Using microspectrophotometry to examine jumping spiders collected in Slovenia, the team found no evidence of a red photoreceptor. The experts also looked for colored filters that might shift green sensitivity to red, but found that there were none.



The researchers ultimately determined that, most likely, bright red colors appear no different than black markings to these jumping spiders.



"To quantify and visualize whether females may nevertheless be capable of discriminating red from black color patches, we take multispectral images of males and calculate photoreceptor excitations and color contrasts between color patches," explained the study authors&nbsp;&nbsp;



"Red patches would be, at best, barely discriminable from black, and not discriminable from a low-luminance green."



“It’s a bit of a head-scratcher, what’s going on here,” said study co-author Professor Nathan Morehouse. “We haven’t solved the mystery of what the red is doing.”&nbsp;



Even though animals use color in all sorts of ways, including camouflage, it’s not always apparent what bright colors might signify, according to Professor Morehouse. “We spent a lot of time talking about it as a group. What else could it be? I feel there’s an interesting story behind the mystery."



Study senior author Cynthia Tedore, a research associate at the University of Hamburg, said the results of the research were surprising.



“Males have bold red and black coloration on their forward-facing body surfaces which they display during their courtship dances; whereas, females lack red coloration altogether. This initially suggested to us that the red color must play some role in mate attraction," said Tedore.



“Instead, we found that red and black are perceived equivalently, or nearly so, by these spiders and that if red is perceived as different from black, it is perceived as a dark ‘spider green’ rather than red."



The researchers believe that the spider’s red and black colors may possibly improve defensive camouflage.



“For predators with red vision, at natural viewing distances, the spider's red and black color patches should blur together to become an intermediate orangish-brownish color, which would help the spider blend in with its leaf litter habitat better than all-black coloration would,” said Tedore.



The experts noted that there are many colorful jumping spiders that see red perfectly well. There are also many dull-colored spiders that have great color vision.



The study is published in the journal <a href="https://www.springer.com/journal/114">The Science of Nature</a>.



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By <a href="http://csexton@earth.com">Chrissy Sexton</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

Scientists find a colorful jumping spider that is color blind

In a new study from the University of Cincinnati, researchers...

A new study from <a href="https://www.anu.edu.au/">Australian National University</a> (ANU) creates a stark choice: step up conservation efforts or lose the regent honeyeater, a beautiful <a href="https://www.earth.com/news/songbirds-and-humans-use-similar-speech-patterns/">songbird</a>, within 20 years. The new study reveals that even the current intensive conservation efforts aren’t enough.



“The regent honeyeater population has been decimated by the loss of over 90 per cent of their preferred woodland habitats,” said study lead author Professor Rob Heinsohn.



"Less than 80 years ago, it was one of the most commonly encountered species, ranging from Adelaide to Rockhampton. Now it is on track to follow the dodo into extinction.”



There are currently less than 300 regent honeyeaters left, making it one of Australia’s rarest birds. Habitat destruction forces the remaining honeyeaters to compete with larger birds for less habitat.



In 2015 the ANU researchers began an intensive research project focused on gaining greater understanding of the regent honeyeater’s decline. After years of field work, the scientists discovered that the decline in nest success was due to predation by other bird species and possums.&nbsp;



In the new research, the scientists used their hard won field data to create a population model that predicts the bird’s future population.&nbsp;



“Our models show that current conservation efforts have provided essential life support for the regent honeyeaters, but do not go far enough," said study co-author Dr. Ross Crates. “We were able to isolate the three key conservation priorities necessary to secure the birds’ future."&nbsp;



The first conservation priority the research lays out is a doubling of nest success rates in both wild and zoo bred animals, facilitated by protecting the nests from predators.&nbsp;



Next captive breeding efforts releasing birds into the Blue Mountains must increase and remain steady for twenty years in addition to nest protection.&nbsp;



Lastly, the research emphasizes that the regent honeyeater can only survive into the future if more habitat is preserved and restored.&nbsp;



“Without more habitat, reintroductions and nest protection efforts will be futile, because the flock sizes will never reach the critical mass needed for the birds to breed safely without our protection," said Professor Heinsohn.&nbsp;&nbsp;



"Our study provides both hope and a dire warning - we can save these birds, but it will take a lot of effort and resources over a long time to pull it off.”&nbsp;



The study is published in the journal <a href="https://www.journals.elsevier.com/biological-conservation">Biological Conservation</a>.



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By <a href="mailto:zachfitzner@yahoo.com">Zach Fitzner</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

How can we save the regent honeyeater from extinction?

A new study from Australian National University (ANU) creates a...

According to current scientific knowledge, the history of life on Earth was marked until now by five mass <a href="https://www.earth.com/news/volcanic-fertilization-led-to-severe-mass-extinction-event/">extinctions</a>, which were caused by natural phenomena and resulted in great global losses of biodiversity. In a new study, a group of biologists from <a href="https://manoa.hawaii.edu/">University of Hawai‘i at Mānoa</a> and the <a href="https://www.mnhn.fr/en">National Museum of Natural History</a> in Paris, France, argue that we are currently experiencing a Sixth Mass Extinction which, in contrast to the previous ones, is caused entirely by human activities.



By extrapolating from estimates obtained through the analysis of snail and slug populations, the scientists have shown that, since 1500, the Earth could have lost between 7.5 percent and 13 percent of the approximately two million of known species, thus between 150,000 to 260,000 species.



“Drastically increased rates of species extinctions and declining abundances of many animal and plant populations are well documented, yet some deny that these phenomena amount to mass extinction,” said&nbsp;study lead author Robert Cowie, a research professor of Biosciences at the University of Hawai’i.



“This denial is based on a biased view of the crisis which focuses on mammals and birds and ignores invertebrates, which of course constitute the great majority of biodiversity. Including invertebrates was key to confirming that we are indeed witnessing the onset of the Sixth Mass Extinction in Earth’s history.”



According to Professor Cowie and his colleagues, the situation is not the same everywhere on Earth. Although increasingly more marine species are threatened, the crisis affecting the seas and oceans is not so severe as that impacting the land. Moreover, on land, island species are more affected than continental ones, and a much larger number of terrestrial animals are endangered in comparison to plants.



Unfortunately, this ongoing extinction is denied by most of the people, including key political actors and policy-makers, and while conservation initiatives have been successful for certain charismatic animals, they cannot target all endangered species and reverse the overall thread of extinction.



“Despite the rhetoric about the gravity of the crisis, and although remedial solutions exist and are brought to the attention of decision-makers, it is clear that political will is lacking,” said Professor Cowie. “Denying the crisis, accepting it without reacting, or even encouraging it constitutes an abrogation of humanity’s common responsibility and paves the way for Earth to continue on its sad trajectory towards a Sixth Mass Extinction.”



The study is published in the journal <a href="https://onlinelibrary.wiley.com/doi/10.1111/brv.12816">Biological Reviews</a>.&nbsp;&nbsp;&nbsp;



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By <a href="mailto:andrei.ionescu5891@gmail.com">Andrei Ionescu</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

The Sixth Mass Extinction is currently in progress

According to current scientific knowledge, the history of life on...

When wild creatures gather at watering holes, they also bring along their parasites, according to a new study from <a href="https://www.ucsb.edu/">UC Santa Barbara</a>. The experts report that cattle and elephants have the highest increased risk of exposure to the <a href="https://www.earth.com/news/if-primates-go-extinct-so-will-their-parasites/">parasites</a>.&nbsp;



"We think about watering holes as being iconic centers of these majestic animals, but they are also hotspots for the parasites that infect these animals," said study co-author Georgia Titcomb.&nbsp;



The researchers set out to investigate how watering holes may influence the distribution of the parasites across savannas in central Kenya.&nbsp;



The study revealed that parasite density is much higher around water sources compared to the surrounding landscape. The exposure risk varied among animal species, and the results suggest that cattle and elephants have by far the greatest risk. In fact, potential parasite exposure for cattle was 143 times higher, and 67 times higher for elephants.&nbsp;



Titcomb said she expected watering holes to aggregate parasites, leading to higher exposure for hosts. "But we didn't expect quite the degree of variation among different wildlife species. The animals that were most strongly affected, and that really followed our expectations, were ones that are quite water dependent: elephants and cattle."



The researchers also surveyed 17 watering holes and 17 dry locations at the Mpala Research Centre, in central Kenya, as well as three wet and dry sites at Ol Pejeta Conservancy. The team found that in the driest areas and time periods, parasite density around water sources was more than 150 times higher than that of locations without water.



"If a cattle herder wants to reduce the chances that their cattle are exposed to parasites, they may want to avoid grazing their animals within 150 meters of water," said Titcomb.&nbsp;



Next, she hopes to investigate how parasite infections in cattle might affect wildlife. "Because cattle are so numerous, their infection patterns have really strong potential to affect less numerous wildlife in the area."



The study is published in the journal <a href="https://www.nature.com/ncomms/">Nature Communications</a>.



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By <a href="http://csexton@earth.com">Chrissy Sexton</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

When animals flock to watering holes, so do their parasites

When wild creatures gather at watering holes, they also bring...

Many animal species exhibit behaviors that are linked to moon phases. A new study led by <a href="https://www.lsu.edu/">Louisiana State University</a> (LSU) and the <a href="https://www.ufl.edu/">University of Florida</a> is one of the first to investigate the connections between lunar phases and shark attacks. The findings suggest that more shark attacks occur during fuller phases of the moon.



The researchers analyzed a global shark attack record (<a href="https://www.floridamuseum.ufl.edu/shark-attacks/">The International Shark Attack File</a>) collected during over half a century (from 1960 to 2015) and discovered an unmistakable correlation between a large number of these attacks and periods with higher lunar illumination. However, it is not yet clear what the precise cause of this phenomenon is.&nbsp;



“It’s not a matter of more light at night for sharks to see. Most shark attacks occur in the daylight. However, the moon can exert other forces on Earth and its oceans in ways that are much more subtle—for example, the gravitation pull that we see affect the tides,” explained study co-author Steve Midway, an associate professor of Fisheries Ecology and Statistics at LSU.



According to Professor Midway and his colleagues, it is still too early to claim that lunar illumination is a causative factor for shark attacks. Since the relationship between moon phases and shark attacks may not be causal, scientists are not necessarily claiming that there are any immediate risk management benefits arising from these findings. Yet, the study contributes to a better understanding of shark behavior, which could help risk management in the future.



“Ultimately, moon phase and lunar illumination will not likely be a strong predictor that alone can forecast risk of shark attack. Local environmental variables are expected to continue to be more practical information for assessing risk.”&nbsp;



“However, the results here strongly support the idea that moon phase does play a role in overall risk of shark attack, and if future studies are able to consider local and regional environmental conditions along with lunar illumination, both understating shark attacks and forecasting risk may improve,” the authors concluded.



The study is published in the journal <a href="https://www.frontiersin.org/articles/10.3389/fmars.2021.745221/full">Frontiers in Marine Science</a>.



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By <a href="mailto:andrei.ionescu5891@gmail.com">Andrei Ionescu</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

Shark attacks linked to phases of the Moon

Many animal species exhibit behaviors that are linked to moon...

Eyes are important. They help <a href="https://www.earth.com/news/some-plants-wont-survive-the-loss-of-seed-dispersing-animals/">animals</a> find food and avoid becoming a meal themselves. Eyes also help animals scope out potential mates and watch out for rivals.&nbsp;



Looking into the eyes of a fossil can thus tell you a lot about how the creature once lived. Was the animal nocturnal or diurnal? An active hunter or shy and retiring? Unfortunately, however, eyes are rare fossils and scientists don’t often get an opportunity to look at them.&nbsp;



A research team spent years examining the eyes of a 95-million-year-old fossil crab,&nbsp;Callichimaera perplexa, found in the Colombian Andes. The crab was first described in 2019 by Harvard postdoctoral fellow Javier Luque. The fossil had preserved unusual elements of both the outer eye and internal structures.&nbsp;



In a new study led by Luque and scientists at Yale University, it is suggested that Callichomaera perplexa was a rare, active swimming predator. Much of this conclusion comes from examination of the eyes, which are quite large for those of an adult crab.&nbsp;



To make sure that they were in fact looking at an adult crab rather than an immature stage where eyes appear larger, Yale PhD candidate Kelsey Jenkins examined more than 1,000 crab specimens, both living and extinct. The research involved looking at crabs at different stages of development to finally determine that indeed, Callichomaera perplexa was an adult with exceptionally large eyes.&nbsp;&nbsp;&nbsp;



“Having such big and unprotected eyes implies that they were exposed at all times, plus eyes that big impose a huge investment of energy and resources to maintain them. Thus, this animal must have relied considerably on vision,” said Luque.



&nbsp;“If something has eyes this big, they're definitely very highly visual. This is in stark contrast to crabs with tiny, vestigial eyes where they may only be 1 to 3% of the animal's body size,” said Jenkins.



Further research showed that the crab had high visual acuity, comparable to other predators such as dragonflies and mantis shrimp. Its vision was adapted to high light environments, meaning the animal was probably most actively hunting during the day.&nbsp;



“Even though it’s the cutest, smallest crab, the big eyes of Callichimaera and its overall body form with unusually large oar-like legs indicate that it might have been a fierce, swimming predator, rather than a bottom-crawler as most crabs are,” said Luque.



Image Credit: Masato Hattori



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By <a href="mailto:zachfitzner@yahoo.com">Zach Fitzner</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

Secrets of a big-eyed crab fossil revealed

Eyes are important. They help animals find food and avoid...

In the past, when climates changed, forests became distributed more to the north or to the south of their previous locations. This is not to say that the trees, themselves, moved. Rather, the ranges of the tree species changed. For example, fossil plant and pollen records show that the ranges of tree species shifted northward at a rate of 50km per century as the climate warmed after the retreat of the North American ice cap.&nbsp;



Tree range migration is facilitated by the movement of seeds. When the climate changes, trees begin to form more seeds; these get spread around by dispersal agents and may germinate in areas that are more favorable for growth. Although wind and water may carry some seeds, the vast majority of trees depend on animals to disperse them to new areas. But now, many of these seed-dispersing animals are themselves threatened, as climate changes and habitats are lost.



In&nbsp;<a href="http://www.science.org/doi/10.1126/science.abk3510?adobe_mc=MCMID%3D84587913426847399401258317155412422308%7CMCORGID%3D242B6472541199F70A4C98A6%2540AdobeOrg%7CTS%3D1641994662">a study</a>&nbsp;featured on the cover of this week’s issue of&nbsp;<a href="https://www.science.org/">Science</a>, U.S. and Danish researchers consider how the loss of species of birds and animals will impact the ability of plants to adapt to human-induced climate change in future. While animals can often fly, walk, run or swim to more suitable areas, trees cannot escape the heat. Tree species that need to move their offspring away from warmer temperatures will only be able to do so via the activities of seed-dispersal agents, such as mammals and birds.&nbsp;



“Some plants live hundreds of years, and their only chance to move is during the short period when they're a seed moving across the landscape,” said <a href="https://www.rice.edu/">Rice University</a> ecologist&nbsp;<a href="https://www.evanfricke.com/">Evan Fricke</a>, the study's first author. “If there are no animals available to eat their fruits or carry away their nuts, animal-dispersed plants aren’t moving very far."



In collaboration with researchers from the University of Maryland, Iowa State University and Aarhus University, the Rice team used machine learning and data from thousands of field studies to map the contributions of seed-dispersing birds and mammals worldwide. They compared maps of seed dispersal today with maps showing what dispersal would look like if there were no human-caused extinctions or species range restrictions.



The experts also used data synthesized from field studies around the world to train a machine-learning model for seed dispersal, and then used the trained model to estimate the loss of climate-tracking dispersal caused by animal declines.



Fricke explained that developing estimates of seed-dispersal losses due to animal and bird extinctions or changes in their ranges required two significant technical advances: “First, we needed a way to predict seed-dispersal interactions occurring between plants and animals at any location around the world."



For this, they used data on species interactions from over 400 field studies that detailed how many seeds are dispersed by particular species of birds and mammals, how far they are dispersed and how well those seeds germinate. Based on this data, the researchers could predict interactions between plants and seed dispersers.



“Second, we needed to model how each plant-animal interaction actually affected seed dispersal,” said Fricke. “For example, when an animal eats a fruit, it might destroy the seeds or it might disperse them a few meters away or several kilometers away.”



The results of the study showed that many seed-dispersing mammals and birds have already been lost, particularly in temperate regions across North America, Europe, South America and Australia. In addition, if currently endangered species go extinct, tropical regions in South America, Africa and Southeast Asia would be severely affected.&nbsp;&nbsp;



“We found regions where climate-tracking seed dispersal declined by 95%, even though they’d lost only a few percent of their mammal and bird species,” said Fricke.&nbsp;



The findings showed that the ability of animal-dispersed plants to keep pace with climate change has been reduced by 60% due to the loss of mammals and birds that help such plants adapt to environmental change.&nbsp;



“In addition to the wake-up call that declines in animal species have vastly limited the ability of plants to adapt to climate change, this study beautifully demonstrates the power of complex analyses applied to huge, publicly available data,” said Doug Levey, program director of the National Science Foundation’s (NSF) Directorate for Biological Sciences, which partially funded the work.



Fricke explained that the study is the first to quantify the scale of the seed-dispersal problem globally and to identify the regions most affected. He emphasized that declines in the populations of seed dispersers highlight an important intersection between the climate and biodiversity crises impacting natural environments today.



“Biodiversity of seed-dispersing animals is key for the climate resilience of plants, which includes their ability to continue storing carbon and feeding people,” he said, adding that restoration of ecosystem connections in natural habitats could counteract some declines in seed dispersal, but not all of them. People also rely, both economically and ecologically, on seed-dispersing birds and mammals to ensure the supply of important resources.&nbsp;



“Large mammals and birds are particularly important as long-distance seed dispersers and have been widely lost from natural ecosystems,” said Svenning, the study’s senior author. “The research highlights the need to restore faunas to ensure effective dispersal in the face of rapid climate change.”&nbsp;



“When we lose mammals and birds from ecosystems, we don’t just lose species. Extinction and habitat loss damage complex ecological networks," said Fricke. "This study shows animal declines can disrupt ecological networks in ways that threaten the climate resilience of entire ecosystems that people rely upon.”



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By <a href="mailto:bosman@truewan.co.za">Alison Bosman</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

Some plants won't survive the loss of seed-dispersing animals

In the past, when climates changed, forests became distributed more...

Bertia cambojiensis

Taxonomic tree: