North Sea slugs discovery


Flabellina verrucosa snail, photo by Daniel Hershman

During recent marine biologists‘ research in the Dutch part of the North Sea near Dogger Bank, two sea slug species, new for the Netherlands were discovered, Dutch Vroege Vogels radio reported today.

They are Flabellina verrucosa and Tenellia viridis.

This Dutch NOS TV report names a third sea slug species new for the Netherlands: Diaphorodoris luteocincta.

New Zealand giant insect escapes from pigs


This video says about itself:

Tusked Weta Vs Foraging Pig – Wild New Zealand – BBC Earth

22 June 2017

The Tusked Weta is New Zealand’s equivalent of a mouse and a worthy snack for a foraging pig. This weta however is an escape artist and when necessary can take quite extreme action to evade capture.

Ants and dead dragonfly


This 20 June 2017 video is about a dragonfly killed by a cat. After its death, the dragonfly attracted many ants.

Eight-year-old Gianni from the Netherlands made this video.

Spineless creature in Washington, DC swamp studied


Stygobromus hayi, photo by Michelle Brown

From the University of Illinois at Urbana-Champaign in the USA:

Spineless creature studied in DC swamp

Its name is Stygobromus hayi, the Hay’s Spring amphipod. It is spineless. It lacks vision. It is an opportunistic feeder, consuming whatever resources are available — perhaps including the remains of its own kind.

That is where its similarities to some of Washington, D.C.’s more notorious megafauna end. And while this tiny creature has been the subject of scientific inquiry in recent years, researchers report on a way to survey it without threatening its existence, as other studies had done.

The Hay’s Spring amphipod lives in swampy areas called seepage springs where groundwater sometimes spills out onto the surface of Rock Creek Park, in Washington, D.C., its only known home in the world. Because it is so rare, and perhaps also because of its prestigious ZIP code and proximity to the National Zoo, this tiny crustacean is on the U.S. endangered species list.

“Yes, it’s small, it’s white, it’s eyeless, it lives underground,” said Matthew Niemiller, an ecologist with the Illinois Natural History Survey who led a recent study to search for the creature in its Rock Creek Park home. “It’s not a cute, cuddly or charismatic species. But we’re still learning more and more about groundwater ecosystems. And there is evidence that these crustaceans are important indicators of groundwater quality, and may play important roles in water purification and nutrient cycling over time.”

The Hay’s Spring amphipod‘s subterranean habitat makes it particularly difficult to study, Niemiller said.

“To find out where species are located and how many there are, we have to disturb the site,” he said.

This normally involves sifting through waterlogged leaves in muddy seepage areas, where underground springs leak out to the surface.

“And because these critters are small — no more than a centimeter long — and a couple of other species look very similar to S. hayi, we would have to sacrifice any individuals we find and take them back to the lab to identify them,” he said. “Since this is an endangered species, that’s something we don’t want to do.”

Niemiller and his colleagues decided to try a different approach, called eDNA. They sampled water in seepage springs where S. hayi and other Stygobromus species had previously been sighted and in others where they had not. The team filtered the water on site, returning to the lab to check their filters for the animal’s DNA.

“This environmental DNA approach has successfully detected larger aquatic animals like salamanders, but no studies had previously used this technique to hunt for invertebrates in groundwater,” Niemiller said.

All creatures shed their DNA into the environment, but the researchers didn’t know if their target animal would slough off enough genetic material to be detectable in their samples. Water quality also was an issue: The seepage springs are muddy and loaded with acidic plant tannins, which can inhibit polymerase chain reaction, the key method for amplifying and detecting DNA in environmental samples.

The researchers overcame the latter problem, however, using chemicals known to remove potential PCR inhibitors.

Their analysis detected S. hayi DNA in samples from three sites where the creature had been seen before, and in a fourth new seepage spring nearby. The researchers also found the DNA of a closely related species, Stygobromus t. potomacus, in four of 10 springs sampled.

“We now know that eDNA is going to be a really worthwhile tool — at least for aquatic species in difficult-to-access habitats,” Niemiller said. “You could go to a spring outflow, take a water sample, and see what you might detect there with a limited outlay of labor, time and money.”

The method has its limitations, however. Environmental DNA sampling can tell researchers whether something is present or absent, but not how many of the targeted organisms are present.

“We also don’t know how long DNA persists in these systems and whether we’re detecting animals that are still alive,” Niemiller said.

The new study demonstrates, however, that this is a viable method to supplement other, more detailed studies of aquatic organisms, he said.

“As funding becomes tighter, we need to think about more efficient ways to monitor and protect these species,” he said.

Jewel scarab beetles look like gold, why?


This video says about itself:

Jewel Scarab in Costa Rica -Chrysina

4 February 2014

Here is a video of a lovely creature I came across during a rain forest exploration. I love insects and this one really took the cake. It’s body was was a like a mirror that reflected all the colors around it.

From the University of Exeter in England:

Secret of why jewel scarab beetles look like pure gold, explained by physicists

‘All that glitters is not gold,’ finds research program into way jewel beetles reflect light

June 15, 2017

The secrets of why Central American jewel scarab beetles look like they are made from pure gold, has been uncovered by physicists at the University of Exeter.

The ornate beetles, which have a brilliant metallic gold colour, are highly valued by collectors. But until now the reasons behind their golden iridescent hue, have not been fully understood.

University of Exeter physicists specialising in colour and light have done experiments exploring the origin of the scarab beetles’ striking metallic golden appearance, showing that the golden beetles have a unique ‘optical signature’. The structure of the beetle and its armour uniquely manipulates the way the light is reflected so that it looks like pure gold.

Their results are published in the Journal of the Royal Society Interface.

Professor Pete Vukusic, a physicist specialising in light and colour, led the research which involved experiments and advanced modelling. He found that the golden appearance is due to the high reflectiveness of the beetles’ exoskeleton, which also manipulates a property of the light called its polarisation: the orientation of the reflected light wave‘s oscillations.

The scientists mapped the optical signature of the beetle’s Chrysina resplendens‘ colour, and found it was unusually ‘optically-ambidextrous’, meaning that it reflects both left-handed and right-handed circularly-polarised light.

Professor Vukusic said: “The brilliant golden colour and distinctive polarised reflection from the scarab beetle Chrysina resplendens sets it completely apart from the hundreds of thousands of other beautiful and brightly coloured animals and plants across the natural world. Its exoskeleton has a bright, golden appearance that reflects both right-handed and left-handed circularly-polarised light simultaneously. This characteristic of Chrysina resplendens appears to be an exceptional and wonderfully specialised characteristic in currently known animals and plants. It will serve as a valuable platform from which bio-inspired optical technologies can spring.”

The golden jewel beetle is prized by collectors because of its resemblance to the precious metal.

Other scarab beetles, valued by ancient cultures such as the Egyptians for use as amulets which were sometimes wrapped in the bandages of mummies, are a jewel-like green and blue colours. The vast majority of brightly-coloured beetles tend to be green and do not reflect polarised light. These beetles, in comparison to the brilliant golden colour of Chrysina resplendens, lack much more specialised aspects of their exoskeleton’s finely detailed structure.

Dr. Ewan Finlayson, research fellow on the project, said: “We were drawn to the study of this jewel scarab not only by its striking metallic golden appearance, but also by its ability to control a less obvious property of the reflected light: the polarisation. We have learned that there is great subtlety and detail to be found in these optical ‘signatures’ and in the elaborate natural structures that generate them.”

The golden jewel scarab beetle Chrysina resplendens, mainly found in the Americas, has evolved an exoskeleton that contains intricate nano-structures that are responsible for its appearance.

The spacing of the repeating layers of the nano-structures is found to vary over a specific range through the exoskeleton — a key property that causes the simultaneous reflection of a range of visible colours. It is this fact that explains the very bright reflection as well as the golden hue.

The nano-structured exoskeleton is composed of natural materials including chitin and various proteins. In addition to their brilliant reflectiveness, these structures are remarkable in the way they manipulate the way polarised light is reflected.

Their nanostructures produce circularly-polarised light, where the orientation of the light’s oscillations rotate as the light travels. The two possible directions of rotation are referred to as left handed and right handed.

The experiments build on the work of an early American scientist called Michelson who, in 1911, looked at the polarised reflection from many different Chrysina beetles, and on the work of Anthony Neville (then at Bristol University) in 1971, who began looking more closely at Chrysina resplendens.

There are around 100 species of Chrysina jewel scarab, which are found exclusively in the New World, mostly in Mexico and Central America. The species Chrysina resplendens is found in Panama and Costa Rica. Chrysina scarabs typically live in mountain forests. The larvae feed on rotting logs of various tree species, while the adults feed on foliage. The larval form lasts for several months to a year, and pupation takes a month or two. After the adult emerges it lives for about a further three months, although this span probably varies between species.

One explanation for the highly-reflective appearance of the beetle exoskeleton is crypsis: the ability of the animal to blend in to its surroundings.

Dr Martin Stevens, Associate Professor of Sensory and Evolutionary Ecology at the University of Exeter and an expert in animal vision, colour change and camouflage, said: “It is not absolutely clear why these beetles are a bright golden colour, but one option is that it somehow works in camouflage under some light conditions. The shiny golden colour could also change how the beetle is seen as it moves, potentially dazzling a would-be predator. There are many species which are iridescent but jewel beetles are one of the most charismatic and brightly coloured, and their colour might be used in mating. However, it is not clear how other beetles see the gold colour and reflected light. Many small mammals would not be able to distinguish the golden colour from reds, greens, and yellows, but a predatory bird would likely be able to see these colours well.”

Ocean predatory animals are growing


This video says about itself:

17 November 2016

Researchers discovered snail species that use their shells to hit predators. Snails were thought to withdraw into their shells when attacked, but land snail species Karaftohelix gainesi and Karaftohelix selskii manifest an active defence behaviour, counterattacking predators by swinging their shells.

Credit:

Parallel evolution of passive and active defence in land snails.

Yuta Morii, Larisa Prozorova & Satoshi Chiba.

Scientific Reports.

From Science News:

Ancient attack marks show ocean predators got scarier

Holes in shells reveal predators that kill by drilling just kept getting bigger

By Susan Milius

4:12pm, June 15, 2017

In pumped-up sequels for scary beach movies, each predator is bigger than the last. Turns out that predators in real-world oceans may have upsized over time, too.

Attack holes in nearly 7,000 fossil shells suggest that drilling predators have outpaced their prey in evolving ever larger bodies and weapons, says paleontologist Adiël Klompmaker of the University of California, Berkeley. The ability to drill through a seashell lets predatory snails, octopuses, one-celled amoeba-like forams and other hungry beasts reach the soft meat despite prey armor. Millions of years later, CSI Paleontology can use these drill holes to test big evolutionary ideas about the power of predators.

“Predators got bigger — three words!” is Klompmaker’s bullet point for the work. Over the last 450 million years or so, drill holes have grown in average size from 0.35 millimeters to 3.25 millimeters, Klompmaker and an international team report June 16 in Science. Larger holes generally mean larger attackers, the researchers say, after looking at 556 modern drillers and the size of their attack holes.

Prey changed over millennia, too, but there’s no evidence for a shift in body size. The ratio of drill-hole size to prey size became 67 times greater over time, the researchers conclude.

It’s “the rise of the bullies,” says coauthor Michal Kowalewski of the University of Florida in Gainesville.

All these data on shell holes allow researchers to test a key part of what’s called the escalation hypothesis. In 1987, Geerat Vermeij proposed a top-down view of evolutionary change, where predators, competitors and other enemies growing ever more powerful drive the biggest changes in their victims. This wasn’t so much an arms race between predators trading tit for tat with their prey as a long domination of underdogs repeatedly stomped by disproportionate menace. (Unless the prey somehow flips the relationship and can do deadly harm in return.) Vermeij, now at the University of California, Davis, and others have drawn on escalating threats to explain prey evolutionary innovations in thick shells, spines and spikes, mobility, burrowing lifestyles and toxins.

One aspect of escalation scenarios has been especially hard to test: the idea that predators can become more dangerous and a stronger evolutionary force over time. Drill holes suggesting bigger, more powerful attackers allowed a rare way of exploring the idea, Klompmaker says. He now reads the deep history as showing predators escalated in size, but prey didn’t.

The energetics worked out, in large part, because early hard-shelled prey called brachiopods — a bit like clams but with one shell-half larger than the other — became scarcer over time, while clams and their fellow mollusks grew abundant. Mollusks typically have more flesh inside their shells than brachiopods, and prey overall grew denser on the ocean bottom. Killer drillers, able to dine at this buffet, could thus support bigger bodies even when prey size wasn’t rising, too.

Prey don’t make drilling easy, Klompmaker says. An hour’s work gets a typical modern predatory snail only about 0.01 to 0.02 millimeters deeper into a mollusk shell. So finally striking lunch could take days of effort with the thickest shells. And that’s with specialty equipment: A snail alternates grinding away using a hard, rasplike driller and then switching to its accessory boring organ that releases acids and enzymes, weakening the drilling spot for the next bout.

The role of such animal clashes in evolution has been notoriously difficult to study, says marine ecologist Nick Dulvy of Simon Fraser University in Burnaby, Canada. Nutrients, climate and other factors that don’t swim away into the blue are much easier to measure. Even after a robust century of ecological study, “the discoveries that otters propped up kelp forests, triggerfishes garden coral reefs, and wolves and cougars create lush diverse watersheds are comparatively recent,” Dulvy says. Until the new drill-hole study, he could think of only one earlier batch of evidence (crabs preying on mollusks) for the long rise of predators as an evolutionary force.

The story from drill holes, says Vermeij, is “very convincing.”