California’s Killer Bees Are Spreading North

Bad news for apiphobes: “Killer” bees are on the move in the United States.

Scientists from the University of California, San Diego recently collected hundreds of bees around the Golden State to determine how far north hybrid honeybees, or Africanized bees, have spread since they first arrived in the state in 1994.

They found that Africanized bees — which possess genes from both European and African honeybees — now live as far north as California’s delta region (about 25 miles, or 40 kilometers, south of Sacramento). And in the southern part of the state, so-called “killer” bees run the show. About 65 percent of the honeybeesthat buzz around San Diego County have a mix of European and African genes, the researchers found. [No Creepy Crawlies Here: Gallery of the Cutest Bugs]

“The pattern of Africanization we documented in San Diego County and elsewhere in California appears consistent with patterns previously documented in Texas, where Africanized honey bees first appeared in the United States,” Joshua Kohn, a professor of biology at UC San Diego and co-author of the new study, said in a statement.

While Africanized bees have taken up residence throughout the American South, Southwest, Southeast and Western coastal regions, their ability to set up permanent colonies in the northern parts of the country seems to be limited by cold temperatures during the winter months, Kohn said. However, higher temperatures caused by global warming could mean that killer bees may continue to push north in the coming years, he added.

There are a few reasons why the range of Africanized bees in California and other states is important, Kohn told Live Science. For one, these bees are highly aggressive, he said. People in California, Arizona and Texas (as well as several other states) have been seriously injured or killedafter enduring thousands of stings from Africanized bees, which are quick to defend their hives. Knowing where those hives might be is a good starting point for preventing future attacks, Kohn said.

But scientists don’t just want to track the migration of Africanized bees because of their killer instincts. Kohn and Yoshiaki Kono, a graduate student in UC San Diego’s Department of Biological Sciences and lead author of the new bee study, are also curious about the spread of the Africanized bees’ more desirable qualities, such as their resistance to some of the diseases and mites that are killing off honey bees in other parts of the country, Kohn said.

The flight of the honeybee

The story of killer bees started in the 1950s. In an effort to breed honeybees better suited to South America’s tropical climate, a biologist in Brazil imported a subspecies of bee (Apis mellifera scutellata) from southern Africa to interbreed with bees from Europe. But winged insects are hard to contain, and several swarms of African bees escaped into the wild.

The runaway bees bred with local populations of European honeybees, and their hybrid descendants spread, mating with other European bees along the way. This intermingling of the African and European honeybees’ gene pools is known as Africanization because it’s the African genes that generally prevail, according to Kohn. The typical Africanized bee in California has a genome made up of 70 to 80 percent African genes and only 20 to 30 percent European genes, he added. [On the Hunt: Honeybee Scouts Find Food]

African genes, and the qualities they are associated with, are dominant because they are favored by natural selection, Kohn said. An Africanized bee’s slightly larger size and high reproduction rate give it certain advantages over non-Africanized bees, for example.

Africanized bees also appear to be more resistant to certain diseases and parasites compared to European bees, Kohn said. In fact, there are many studies that back up this claim. One study, published in 2010 in the journal Experimental and Applied Acarology, found that Africanized bees may be more resistant to the parasitic mite Varroa destructor (an insidious foe inside bee colonies) because of the bees’ grooming behaviors and the lowered fertility of the mites inside the brood, or honeycomb of the Africanized hive.

Right now, most of California’s Africanized bees are feral — the study found that only 13 percent of managed hives in San Diego County carried the African mitotype (mitochondrial DNA), as opposed to 70 percent of feral hives in the county. Most beekeepers prefer European honeybees because Africanized bees are so much more difficult to manage, Kohn said.

But, there may be a way for beekeepers to get the disease resistance they’re looking for in European bees while minimizing the risk that Africanized bees pose.

“By dissecting the genomes of Africanized honey bees to find regions responsible for advantageous traits, we may be able to combat recent declines in managed honey bee populations that are so critical for food production,” Kohn said.

Disease-resistant bees that aren’t likely to kill anyone could be a win-win for everyone.

Using Animal Control To Get Rid Of Unwanted Critters

Animal Control in Carlsbad, CA is responsible for dealing with most of the animal related disturbances for San Diego County, including all of the incorporated and unincorporated areas within. But you may be at a loss if you should contact the City of Carlsbad, who contracts with the County of San Diego for animal control services, or if you should contact the county itself. Here are a few guidelines you can follow to make sure that you are contacting the right department, as well as ensuring that you are not putting yourself in any unnecessary risk.

If you are just looking to adopt a pet, license one you have already, or any other pet matter that is unrelated to a disturbance you should contact the County of San Diego directly. They operate three shelters, including the one in Carlsbad, so you should not have to contact animal control in Carlsbad at all for any peaceful inquiries. Carlsbad animal control is mostly responsible for dealing with animal disturbances that pose an immediate threat to people or animals. So be sure to ask yourself how urgent your inquiry is, and that should help guide you to the correct organization.

A situation requiring animal control assistance would be suspected abuse to an animal in your neighborhood. If you here constant barking, or desperate shrieks from a nearby cat then you may need to call Carlsbad Animal Control. You should not do any private sleuthing to investigate the situation. First of all, an abused animal can typically display violent tendencies, so you may not want to pose yourself as an intruder.

Secondly, you do not want to risk your credibility by having your neighbor call the police on you for trying to “rescue” his pet. Carlsbad Animal Control employs highly trained individuals who have been primed to investigate such occurrences and determine if any abuse has occurred, and take the animal away from its owner if any danger is posed to it. Always trust the professionals to take care of the problems in their field.

If a dead animal is found on the road then you should contact the City of Carlsbad. Dead animals are not just smelly and unsightly, they can also spread disease. Do not attempt to remove the animal yourself, because you probably do not know for sure what killed it and if it poses any danger to you. Once again, just let the professionals who are paid to take care of this problem remove it for you.

Another major problem can be wild dogs roaming the area. A wild dog can be extremely dangerous, so Carlsbad Animal Control should be contacted. Many of these animals have been abused and are very afraid of people, so any attempt to scare the dog into leaving may backfire, prompting the dog to attack you in defense.

In addition, a wild dog has no way of receiving regular vaccinations, so there is a chance that it could be infected with rabies. Animal Control has the necessary training and tools to safely remove the dog, and wild dog removal should never be attempted without their assistance. And, though they may be a terrible nuisanceFree Articles, Animal Control in Carlsbad is not supposed to respond to a skunk in the backyard or an opossum. So make sure you have a genuine emergency before calling.

Say Aaaah Zoo’s Aardvark Gets 2 Teeth Pulled

Getting a tooth pulled is never fun, but it’s especially irksome if you’re an aardvark. Ali, an aardvark at the Cincinnati Zoo, recently learned this lesson firsthand after two infected teeth landed her in the dentist’s chair.

Aardvarks, the only extant species in the order Tubulidentata, are unusual animals — and they have unusual teeth, said Jack Easley, a Kentucky-based veterinarian who specializes in dentistry. Easley was one of several veterinarians who helped extract Ali the aardvark’s two problematic teeth last month at the Cincinnati Zoo.

Unlike most other mammals, aardvarks don’t have enamel in their teeth. (Enamel is the hard, visible part of the tooth that covers up the more sensitive tissues beneath it.) These soft teeth typically serve aardvarks well, because in their native African habitat, the animals only eat easy-to-chew insects like termitesand ants, Easley told Live Science. [Photos: World’s Cutest Baby Wild Animals]But in zoos, aardvarks don’t always eat soft insects, which may not be readily available. Instead, they eat a special, pelleted feed or some other manufactured food, said Easley, who noted that, sometimes, this diet can lead to dental disease. Ali, who is 11 years old, is also middle-age for an aardvark, which may have contributed to the decline in her dental health, he added.

Zoo staff first noticed that there was a problem with the animal’s health back in January, when Ali developed a weird-looking, swollen eye. The problem seemed to be resolved with a dose of antibiotics, but when the medication was finished, the ulcer came back, said Jenny Nollman, an associate veterinarian at the Cincinnati Zoo.

“When it didn’t clear up completely, we investigated it further,” Nollman told Live Science. “That’s when we got into the CT [cat scan] and MRI [magnetic resonance imaging] — the more advanced imaging — to try to really get a better diagnosis.”

In July, zoo staff accompanied Ali to a nearby hospital to try to pinpoint the root of the problem. The CT scan and MRI suggested that what appeared to be an eye problem was actually a tooth problem, Nollman said. That’s when zoo vets reached out to Easley, one of very few veterinarians in the United States who is board-certified in veterinary dentistry.Ali the aardvark’s two infected teeth. Unlike most mammals, aardvarks don’t have a hard layer of enamel covering the crown of their teeth.

Two of Ali’s molar teeth were so infected that the bone and tissue supporting her teeth had formed what’s known as a periodontal pocket, Easley said. This led to the formation of a fistula, or an abnormal passageway between two body parts that are not usually connected. In Ali’s case, the fistula formed between her sinus and the periorbital sac (the tissue surrounding the eyeball), causing her eyeball to look inflamed and leak out pus.

To fix this problem, Easley and another certified veterinary dentist traveled to Cincinnati to pull out Ali’s infected teeth. But there was one small problem: Unlike humans, aardvarks can’t say “ah.”

In addition to having weird teeth, aardvarks have strange mouths. The animals have long tongues and deep oral cavities, with the teeth located all the way in the back (about 12 inches, or 30 centimeters, inside their mouths). These oral openings are very small, measuring only 1.5 inches (4 cm) across, according to Easley.

To reach inside Ali’s mouth, Easley had to make a small incision in the animal’s cheek. After removing the two infected molars, the veterinarians packed the hole left by the extracted teeth with an antibiotic-coated gauze material and left Ali to heal over the next three to six weeks.

Yesterday (Sept. 1), Nollman performed a checkup, and the resilient little aardvark seemed to be doing quite well, she said, though it will take Ali a few more weeks to fully heal.

“[Ali] has not missed a beat through this whole thing,” Nollman said. “Her appetite has never decreased, and she has been very active.”

290 Million Year Old Creature Could Sprout New Limbs

If an ancient amphibian lost a limb or a tail, it could simply sprout a new one, according to researchers who found fossil evidence of limb regeneration dating back 290 million years.

The finding shows that some Carboniferous and Permian period animals had regenerative abilities a full 80 million years before salamanders, one of the few modern-day animal groups that can fully regenerate their limbs and tail, existed in the fossil record.

The fact that other tetrapods — a group comprised of four-legged vertebrates, including amphibians, reptiles, mammals and birds — had regenerative abilities suggests there are multiple ways to regrow limbs, said study lead researcher Nadia Fröbisch, a paleontologist at the Natural History Museum in Berlin. [Slithery, Slimy: Images of Legless Amphibians]

“Regenerative medicine is an active and very large research field,” Fröbisch told Live Science. Most regenerative medicine is focused on the molecular mechanisms used by modern salamanders, but “we don’t only have to look for things specific to salamanders, but also mechanisms present in all tetrapods,” she said.

Fröbisch has studied limb regeneration in salamanders for years. She’s not alone — at least 100 years ago, researchers noted that salamander limbs develop differently than those of all other tetrapods, and wondered if this helped explain their regenerative abilities.
Sclerocephalus fossil
[Pin It] The fossilized body of the Lower Permian amphibian Sclerocephalus discovered in southwestern Germany. Like today’s salamanders, the ancient Sclerocephalus could also regenerate its limbs, evidence suggests.
Credit: Hwa Ja Goetz, MfN
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When a typical tetrapod limb develops in an embryo, it grows its outer digit (the pinkie) first and inner digits in successive order. But salamanders do the opposite: They grow their inner digit (the thumb side) first and their pinkie last.

For decades, researchers thought that this odd developmental quirk evolved late in evolutionary history, Fröbisch said. However, recent examinations of fossils show that this pattern is older than previously thought, and existed before dinosaurs walked the Earth.

Fossil evidence shows that the salamander’s “backward” digit development is found in various amphibians of the Carboniferous period (359 million to 299 million years ago), and the Permian (299 million to 251 million years ago), including the Apateon, Micromelerpeton and Sclerocephalus, Fröbisch said.

In addition to the backward digit development, a 290-million-year-old Micromelerpeton from a fossil lakebed in southwestern Germany shows evidence of limb regeneration. (Limb regeneration is possible to spot with a trained eye: Sometimes when a limb regrows, it’s slightly deformed — containing fused fingers, for instance — indicating that it’s not an original limb, Fröbisch said.)

But backward formation of the digits isn’t necessary for limb regeneration, the researchers found. Microsaurs — amphibians that looked like lizards and lived about 300 million years ago — could regrow their tails, according to fossil evidence from the Czech Republic. But microsaurs developed digits the typical way — pinkie first.

“All together, the fossil data shows that [developing the thumb side first] in limb development and regeneration don’t always occur together,” Fröbisch said. “It’s not salamander-specific at all. It’s something very ancient.” [Album: Bizarre Frogs, Lizards and Salamanders]

However, the salamander is the only surviving tetrapod that has kept its regenerative abilities. (Lungfish also have these abilities, but they’re poorly studied and aren’t tetrapods, Fröbisch said). Over time, the lineage leading to amniotes (reptiles, birds and mammals, including humans) lost the ability to regrow limbs, she said.

Genetic discovery

In a separate but related new study, researchers examined salamander genetics and found two genes necessary for its formation of backward digits.

“Some time ago, we found a gene called Prod1 that is specific to salamanders and is involved in limb regeneration,” said study author Jeremy Brockes, a research professor of structural and molecular biology at University College London.

So, they knocked out Prod 1 in fertilized newt eggs with a gene-editing tool. As they observed the newts develop, they found that the protein Bmp2, critical for digit formation, was absent in these newts.

Without Prod 1 and Bmp2, the newt couldn’t form its digits on the thumb side first. This indicates that both the gene and protein are necessary for the salamander’s unique digit growth, Brockes told Live Science.

It’s interesting that the other study finds that thumb-side first-limb growth is found in some, but not all, early tetrapod fossils from the Permian era about 290 million years ago, Brockes said.

“This is before the appearance of the salamanders,” he said. “Our results suggest that these attributes, which are found together in present-day salamanders, may be linked by the involvement of common genes such as Prod 1.”

The fossil analyses and genetic findings were published online yesterday (Oct. 26) in the journals Nature and Nature Communications, respectively.

Leaf Eating Caterpillars Use Their Poop to Trick Plants

Caterpillars that munch on corn leaves have developed a clever way to get the most nutrients from their meals: They use their poop to trick the plants into lowering their defenses.

Scientists at Pennsylvania State University recently discovered that fall armyworm caterpillars (Spodoptera frugiperda) can send chemical signals to plants through their poop, or frass.

“It turns out that the caterpillar frass tricks the plant into sensing that it is being attacked by fungal pathogens,” study co-author Dawn Luthe, a professor of plant stress biology at Pennsylvania State University, said in a statement. [In Photos: Animals That Mimic Plants]

Corn plants can deal with only one kind of attack at a time, so while a corn plant is dealing with the perceived “fungal infection,” the caterpillar is left to feast on the plant’s leaves. Normally, a plant will recognize chemical signatures from insect secretions, which helps the plant know when to raise its defenses. In many cases, this includes producing a biochemical that repels herbivores, such as insects.

But chemical signals from the caterpillar’s poop act as crafty diversions, the researchers said.

“The plant perceives that it is being attacked by a pathogen and not an insect, so it turns on its defenses against pathogens, leaving the caterpillar free to continue feeding on the plant,” Swayamjit Ray, a doctoral student in plant biology at Penn State and co-author of the paper, said in a statement. “It is an ecological strategy that has been perfected over thousands of years of evolution.”Fall armyworm caterpillars (Spodoptera frugiperda) feed on corn leaves and crevasses where the leaves meet the stalks.

Caterpillars usually feed on the leaves in the confined whorls of corn plants. The critters typically defecate in the crevasses where the leaves meet the stalk, the researchers said.

Scientists studied the biochemical relationship between fall armyworm caterpillar frass and a plant’s defensive mechanisms by performing two tests. In the first test, the scientists applied frass extract to the leaves of some corn plants and compared caterpillar growth of those that fed on treated leaves with those that munched on untreated leaves.

The second test involved measuring how frass-treated corn leaves affected defensive performance on plants exposed to a fungal pathogen — in this case, spores of a fungus that causes blight in corn (Cochliobolus heterostrophus). The scientists observed that, initially, proteins in the frass activated an insect defense in the plant, but over time, as the corn plants were exposed to more of the protein, the plants’ defenses became altered and instead began to recognize the frass protein as a fungal pathogen instead of an insect waste product. This caused the plant to defend itself against what it saw as a fungal threat instead of an insect threat.

While this may not be good news for plants suffering from a caterpillar infestation, the researchers think it may be possible to isolate the specific components in caterpillar poop that heighten a plant’s defenses against pathogens. If this is the case, the scientists said, farmers could one day develop an organic and sustainable pesticide to prevent infection and disease in crops.

Meet 6 Animals That Predict World Cup Winners

an octopus named Paul correctly predicted the outcome of eight World Cup matches in a row, including the final showdown between Spain and the Netherlands.

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In 2010, after winning worldwide attention as an animal oracle, Paul passed away at the tender age of two and a half – a normal lifespan for an octopus vulgaris. But a raft of other animals have been competing to fill Paul’s, er, shoes in the 2014 World Cup season. So far, however, the would-be successors to Paul the Octopus haven’t been faring so well.

Nelly the Elephant predicted that the German team would overtake the Ghanians in the second round. The match, however, ended in a tie.

Pele the Piranha predicted that the host country of Brazil would defeat Mexico. This match, however, also ended in a tie.

Flopsy the Kangaroo, a.k.a.  the “Predictaroo,” correctly predicted that Brazil would defeat Croatia in the opening match of the World Cup but flopped badly in predicting that Australia would defeat Chile.

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Alves the Tapir also correctly predicted the outcome of the opening match between Brazil and Croatia. But he wrongly predicted that England would prevail over the Netherlands, whose team is still going strong.

Big Head the Turtle was the third animal to correctly predict the outcome of the Brazil-Croatia match. But, like Pele the Piranha, he wrongly predicted that Mexico would beat the host country of Brazil in their second match (it ended in a tie).

So, for now, much hope – at least here in the United States – rides on Nasar, a prognosticating horse who lives inside a 300-year-old farmhouse in Hold, Germany, with his owner, Stephanie Arndt, a doctor. When the online editorial office of a local newspaper enlisted the horse’s help in predicting the winner of the U.S.-Germany World Cup match on June 26, Nasar predicted that the United States would win by kicking a beach ball into a miniature soccer goal with a U.S. flag attached to it.

Could Nasar be the real deal – the never-fail Ouija of the animal kingdom? Stay tuned.

 

Also of Interest

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Birds of a Feather Photos of Hummingbirds Hawks & Jays

In the Chiricahua Mountains of Arizona, black-chinned hummingbirds have a clever strategy to keep their nests safe: They recruit unknowing hawks for home security. Hummingbird nests cluster near hawk nests, and those hawks keep away the predatory jays that snatch hummingbird eggs, researchers reported Sept. 4 in the journal Science Advances. [Read full story about how hummingbirds recruit hawks for protection]A female black-chinned hummingbird (Archilochus alexandri) perches on a twig. The daily survival rate of a hummingbird nest built nearby a hawk’s nest is 31 percent, compared with only 6 percent for hummingbird nests not near hawk roosts. (Credit: Harold F. Greeney, Yanayacu Biological Station

Male Seahorses Act Like Pregnant Mammals Study Suggests

Pregnant male seahorses tend to develop embryos similarly to the way mammals do, new research shows.

In the new study, scientists found a suite of genes that are “turned on” in the pouches of seahorses to keep the baby healthy and growing. Similar gene activity has been found in the wombs of mammals and even reptiles.

As such, the finding could shed light on the evolution of live birth, called viviparity.

Seahorse broods

Seahorses are syngnathid fishes — the only animal family in which males, not females, carry their young. In seahorse sex, the female deposits her eggs into a “brood pouch” on the male’s stomach, where he fertilizes them. The expectant dad then carries the eggs in this pouch during the 24-day gestation period until he gives birth, using abdominal contractions to expel the live young, which are then on their own to survive. [The 10 Wildest Pregnancies in the Animal Kingdom]

Previously, researchers knew little about what took place in the brood pouch of the pot-bellied seahorse (Hippocampus abdominalis) during pregnancy. To find out, an international team of researchers looked at how genes were turned on and off during the course of the expecting dads’ pregnancies. They compared this activity with that found in the brood pouches of nonpregnant males. (Just as nonpregnant women have uteruses, nonpregnant male seahorses have brood pouches.)

They specifically looked at ribonucleic acid, or RNA in the seahorses’ brood pouches  (RNA is produced when a gene is turned on and tells the cell to build the protein that the gene encodes.) Then, they looked for similar gene sequences (and their functions) in publicly available databases.

Pouches and uteruses

Pregnancy led to an uptick in the expression of genes involved in nutrient transport within the brood pouch, the scientists found. “Things like fats, and also calcium, seem to be transported from the dad [to the developing fetus],” said study author Camilla M. Whittington, a postdoctoral researcher at the University of Sydney in Australia. “We also found a whole lot of other genes for things like immune function, so it looks like the seahorse dads can actually help prevent infection in the brood pouch.”

The researchers also found changes in the expression of genes involved in tissue remodeling. These genes may be involved in structural changes to the brood pouch, which thickens and develops more blood vessels when carrying the brood (of several hundred embryos), Whittington said. The team found gene-expression changes associated with immune-system activities (both protecting the embryos from infection and preventing the father’s immune system from rejecting the tissue of his offspring as foreign), gas exchange (so that the embryo can “breathe”), and waste removal.

The brood pouch is said to have the same function as the uterus of mammals and reptiles. Consistent with that idea, the researchers found many similarities between the genes expressed in the male seahorses’ brood pouches and similar genes (called homologues) expressed in the uteruses of female mammals — rats, in particular — and the womb equivalents of reptiles and fish that have live young. Those similarities could potentiality extend to humans, Whittington said. [Infographic: For How Long Are Animals Pregnant?]

“People have looked at gene expression in the rat uterus during pregnancy, whereas we don’t have a similar data set for humans,” Whittington said. “Obviously, it’s kind of difficult to get those kinds of tissue samples, and that’s probably why people haven’t done it. So we found mammalian homologues, and we presume some of them will be human homologues, too, but we don’t have the data to be able to tell.”

Bearing live young

Research of this sort may reveal details about how viviparity evolved, Whittington said. The trait is thought to have evolved independently 150 times in vertebrates, including 23 times in fishes, the authors wrote in the study.

Once animals “stop laying eggs and start having live babies instead, animals are faced with a common set of challenges,” Whittington said. “Somehow, wastes have to be removed from the embryo, somehow oxygen has to be delivered and somehow nutrients have to be delivered.

“There are perhaps a limited number of genetic ways that this could be done, and so this is why we’re seeing the same genes being recruited into pregnancy in these animals,” Whittington added.

This process of turning on certain genes during pregnancy could be an example of convergent evolution, in which evolutionarily separated species develop similar ways of doing things by evolving under similar environmental conditions.

“These animals have evolved pregnancy millions of years apart and also in completely different structures,” Whittington added. This supports the convergent evolution idea. “Mammals use a uterus, whereas the seahorses are using, essentially, modified abdominal skin,” Whittington said.

Alternatively, viviparous animals around today could have had a common ancestor in which these genes were already turned on in the tissues that later evolved to become the uterus and the brood pouch.

“I think our research shows that we are more like other animals than you might think,” Whittington added. “I think it really illustrates that there are commonalities in pregnancies across really diverse vertebrates, and I think that’s really exciting.”

A Mass Die off of the Endangered Saiga Antelope

Bizarre Human Size Sea Scorpion Found in Ancient Meteorite Crater

About 460 million years ago, a sea scorpion about the size of an adult human swam around in the prehistoric waters that covered modern-day Iowa, likely dining on bivalves and squishy eel-like creatures, a new study finds.

The ancient sea scorpions are eurypterids, a type of arthropod that is closely related to modern arachnids and horseshoe crabs. The findings — which include at least 20 specimens — are the oldest eurypterid fossils on record by about 9 million years, said study lead researcher James Lamsdell, a postdoctoral associate of paleontology at Yale University.

The findings are also the largest known eurypterids from the Ordovician period, which began approximately 488 million years ago and ended 443.7 million years ago. The sea creatures measured up to 5.6 feet (1.7 meters) long. [See Images of the Ancient Sea Scorpion]

Researchers dubbed the newfound species Pentecopterus decorahensis, named for Greek warships (penteconter) and the Greek word for wings (pterus) because the sea scorpion was likely a top predator that sped through the water, the researchers said. The species name also honors the Iowa city of Decorah, where the fossils were uncovered.

“The best way to describe this animal is bizarre,” Lamsdell told Live Science. “For a long time, I had trouble being sure that this was one species because there are so many strange things about it.”

Paddle-shaped limbs

An analysis showed that P. decorahensis had specialized limbs that developed as it aged. Its rear limbs are shaped like paddles with joints that appear to be locked in, suggesting that the predator used them as paddles to swim or dig, the researchers said.

Its second and third pairs of limbs were likely angled forward, which suggests they helped the ancient arthropod grab prey. Moreover, the three back pairs of limbs are shorter than the front pair, indicating that P. decorahensis walked on six legs instead of eight.This appendage shows movable and fixed spines. The scale bar represents 0.4 inches (1 cm).

Interestingly, juveniles had different spines on their legs than adults did.

“It looks like the juveniles would have behaved more like horseshoe crabs, sort of walked around on the seafloor, grubbing in the mud, just eating worms or whatever they could find,” Lamsdell said.

With age, their back legs shrank and probably helped the eurypterids balance while swimming. The front legs grew, as did the sharp spines growing on them, “and they could have been used for catching larger prey,” Lamsdell said.

Like other arthropods, P. decorahensis probably molted as it aged. Researchers speculate that eurypterids molted “en masse, and accumulations of molts have been reported from a number of sheltered, marginal marine environments,” the researchers wrote in the study. Perhaps the specimens found in Iowa are molted skin, they said. [Skin Shedders: A Gallery of Creatures That Molt]

Even so, the fossils provide exquisite detail, showing scales, follicles and stiff bristles that once covered the animals. For instance, its rear limbs are covered with dense bristles. Horseshoe crabs have similar bristles that expand the surface area of its paddles as it swims, but P. decorahensis’ smaller bristles suggest they may have been sensory in nature, the researchers said.

The Iowa Geological Survey discovered the fossils during a mapping project of the Upper Iowa River. Researchers subsequently found at least 20 P. decorahensis individuals, and had to dam the river to safely remove the specimens.

Credit: Iowa Geological Survey

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Workers with the Iowa Geological Survey uncovered the fossils in the Upper Iowa River during a mapping survey.

The fossils were found at the bottom of a meteorite impact crater, a scar left from when Earth was battered about 470 million years ago, Lamsdell said. The so-called Ordovician meteor event left a “series of pockmarks” across the United States, and predated the newfound eurypterid fossils by several million years, he added.

Researchers found more than 150 fossil fragments from the site — an 88.5-foot-thick (27 m) formation in northeastern Iowa known as Winneshiek Shale. The fossils are also well preserved, and can be peeled off the rock and studied under a microscope.

“It really looks like an animal that has just shed its skin,” Lamsdell said. “I’ve never seen anything like this before.”

The new study is “exciting material,” said Roy Plotnick, a professor of paleontology at the University of Illinois at Chicago, who was not involved in the study.

“To find something as well preserved as this is pretty exciting, especially given that it’s old and yet has features of more advanced forms,” Plotnick said. “That tells us that somewhere in even older rocks should be even more ancestral forms to find.”