Cuttlefish colours, new study

This February 2018 video says about itself:

Cuttlefish Look Like Squid—and Like Crabs, and Like Algae, and Like Rocks | National Geographic

A new study examines the muscles, nerves, and chemicals that enable cuttlefish—animals related to squid—to change their skin texture, mimicking another animal or their surroundings.


Pre-Cambrian worm discoveries in Mongolia

Reconstruction of the late Ediacaran (ca. 550 million years ago) sea floor with burrows of a worm-like animal.This was the first discovery of such deeply penetrating burrows. Credit: © Nagoya University

From Nagoya University in Japan:

Digging up the Precambrian: Fossil burrows show early origins of animal behavior

March 12, 2018

Researchers led by Nagoya University discover penetrative trace fossils from the late Ediacaran of western Mongolia, revealing earlier onset of the “agronomic revolution”.

In the history of life on Earth, a dramatic and revolutionary change in the nature of the sea floor occurred in the early Cambrian (541–485 million years ago): the “agronomic revolution.” This phenomenon was coupled with the diversification of marine animals that could burrow into seafloor sediments. Previously, the sea floor was covered by hard microbial mats, and animals were limited to standing on, resting on, or moving horizontally along those mats. In the agronomic revolution, part of the so-called Cambrian Explosion of animal diversity and complexity, vertical burrowers began to churn up the underlying sediments, which softened and oxygenated the subsurface, created new ecological niches, and thus radically transformed the marine ecosystem into one more like that observed today.

This event has long been considered to have occurred in the early Cambrian Period. However, new evidence obtained from western Mongolia shows that the agronomic revolution began in the late Ediacaran, the final period of the Precambrian, at least locally.

A team of researchers, primarily based in Japan, surveyed Bayan Gol Valley, western Mongolia, and found late Ediacaran trace fossils in marine carbonate rocks. They identified U-shaped, penetrative trace fossils, called Arenicolites, from 11 beds located more than 130 meters below the lowermost occurrence of Treptichnus pedum, widely recognized as the marker of the Ediacaran–Cambrian boundary. The researchers confirmed the late Ediacaran age of the rocks, estimated to be between 555 and 541 million years old, based on the stable carbon isotope record.

“It is impossible to identify the kind of animal that produced the Arenicolites traces,” lead author Tatsuo Oji says. “However, they were certainly bilaterian animals based on the complexity of the traces, and were probably worm-like in nature. These fossils are the earliest evidence for animals making semi-permanent domiciles in sediment. The evolution of macrophagous predation was probably the selective pressure for these trace makers to build such semi-permanent infaunal structures, as they would have provided safety from many predators.”

These Arenicolites also reached unusually large sizes, greater than one centimeter in diameter. The discovery of these large-sized, penetrative trace fossils contradicts the conclusions of previous studies that small-sized penetrative traces emerged only in the earliest Cambrian.

“These trace fossils indicate that the agronomic revolution actually began in the latest Ediacaran in at least one setting,” co-author Stephen Dornbos explains. “Thus, this revolution did not proceed in a uniform pattern across all depositional environments during the Cambrian radiation, but rather in a patchwork of varying bioturbation levels across marine seafloors that lasted well into the early Paleozoic.”

Jumping spider in Japan

This video says about itself:

Jumping spider (Menemerus brachygnathus (Thorell)) filmed in Toshima-ku, Tokyo, Japan on 11 June 2017. This specimen was about 1 cm in length.


Hawaiian stick spiders, new research

This video says about itself:

A long-tailed spider (Ariamnes cylindrogaster, family Theridiidae) moving along a long horizontal non-sticky line between the branches. This species is known to be a spider-hunting spider (araneophagy). I’m not sure if this one was spinning its unique simplistic web to catch other spiders. Eventually, the spider stretched itself as if mimicking a green pine needle hanging in the air. Filmed in the morning (9:23 am – 9:28 am) of early October 2015 in Japan.

From ScienceDaily:

Hawaiian stick spiders re-evolve the same three guises every time they island hop

March 8, 2018

We don’t usually expect evolution to be predictable. But Hawaiian stick spiders of the Ariamnes genus have repeatedly evolved the same distinctive forms, known as ecomorphs, on different islands, researchers report on March 8 in the journal Current Biology. Ecomorphs — which look the same and live in the same kinds of habitats, but aren’t as closely related as they appear — are surprisingly rare, and the researchers hope that these newly described ones might help us understand what’s behind this strange evolutionary pattern.

The stick spiders live in the forests of the Hawaiian archipelago, over 2,000 feet above sea level, on the islands of Kauai, Oahu, Molokai, Maui, and Hawaii. Although they’re nocturnal arthropods that can’t see well, they’re still brightly and distinctly colored. “You’ve got this dark one that lives in rocks or in bark, a shiny and reflective gold one that lives under leaves, and this one that’s a matte white, completely white, that lives on lichen“, explains Rosemary Gillespie, an evolutionary biologist at the University of California, Berkeley.

These different colorings allow the spiders to camouflage themselves against specific similarly colored surfaces in their respective habitats and avoid their major predator, birds called Hawaiian honeycreepers. But what’s remarkable is that as the spiders have moved from one island to the next during their evolutionary history, these same forms have evolved over and over again. This process produces new species that are more closely related to spiders of different forms on the same island than they are to lookalikes from other islands.

And it happens fast — at least in evolutionary time. A dark spider that hops from an old island to a new one can diversify into new species of dark, gold, and white spiders before gold and white spiders from the old island have time to reach the new one. “They arrive on an island, and boom! You get independent evolution to the same set of forms”, Gillespie says.

It’s also important that these forms are the same each time. “They don’t evolve to be orange or striped. There isn’t any additional diversification”, she says. This, she believes, suggests that the Ariamnes spiders have some sort of preprogrammed switch in their DNA that can be quickly turned on to allow them to evolve rapidly into these successful forms. But how that process might work is still unclear.

It hasn’t really been studied, because ecomorphs aren’t common. “Most radiations just don’t do this”, she says. Typical adaptive radiation, like with Darwin’s finches, usually produces a wide diversity of forms. And convergent evolution, where two different species independently evolve the same strategy for fulfilling a certain niche, doesn’t usually happen repeatedly. There are just a few good examples of this kind of fixed pattern of repeated evolution: the Ariamnes spiders, the Hawaiian branch of the Tetragnatha genus of long-jawed spiders, and the Anolis lizards of the Caribbean.

“Now we’re thinking about why it’s only in these kinds of organisms that you get this sort of rapid and repeated evolution,” Gillespie says. While it’s a question she’s still working on, the three lineages do all live in remote locations, have few predators, and rely on their coloring to camouflage them in a very particular habitat. They are also all free living in the vegetation: neither of the two spider groups builds a web, which means that they, like the lizards, are free to move about and find the kind of habitat they require for camouflage. She hopes that examining what these groups have in common will “provide insight into what elements of evolution are predictable, and under which circumstances we expect evolution to be predictable and under which we do not.”

She also hopes that this research will help the world to understand how much Hawaii’s vulnerable forests still have to offer. “Often, I hear people saying, ‘Oh, Hawaii’s so well studied. What else is there to look at?’ But there are all these unknown radiations that are just sitting there, all these weird and wonderful organisms. We need everyone to understand what’s there and how extraordinary it is. And then we need to see what we can do to protect and conserve what still waits to be described.”


Starfish mass death on English beach

This video from England says about itself:

4 March 2018

Tens of thousands of starfish were washed up on Ramsgate beach in Kent after ‘The Beast From The East’, Storm Emma passed by. The sudden drop in temperature is thought to have killed the sea creatures.

What a pity so many of these beautiful animals died. One should hope that now these starfish will at least help to feed gulls, sanderlings and other birds.


‘Termites, cockroaches more closely related than thought’

This 2015 video is called Termites Are Probably Evolutionary Descendants Of Cockroaches.

By Susan Milius, 7:00am, March 1, 2018:

It’s official: Termites are just cockroaches with a fancy social life

Reordering demotes one infamous insect group to being a mere branch of an equally infamous one

Termites are the new cockroach.

Literally. The Entomological Society of America is updating its master list of insect names to reflect decades of genetic and other evidence that termites belong in the cockroach order, called Blattodea.

As of February 15, “it’s official that termites no longer have their own order”, says Mike Merchant of Texas A&M University in College Station, chair of the organization’s common names committee. Now all termites on the list are being recategorized.

The demotion brings to mind Pluto getting kicked off the roster of planets, says termite biologist Paul Eggleton of the Natural History Museum in London. He does not, however, expect a galactic outpouring of heartbreak and protest over the termite downgrade. Among specialists, discussions of termites as a form of roaches go back at least to 1934, when researchers reported that several groups of microbes that digest wood in termite guts live in some wood-eating cockroaches too.

Once biologists figured out how to use DNA to work out genealogical relationships, evidence began to grow that termites had evolved as a branch on the many-limbed family tree of cockroaches. In 2007, Eggleton and two museum colleagues used genetic evidence from an unusually broad sampling of species to publish a new tree of these insects (SN: 5/19/07, p. 318). Titled “Death of an order”, the study placed termites on the tree near a Cryptocercus cockroach.

Cryptocercus roaches live in almost termitelike style in the Appalachian Mountains, not too far from chemical ecologist and cockroach fan Coby Schal at North Carolina State University in Raleigh. Monogamous pairs of Cryptocercus roaches eat tunnels in wood and raise young there. The offspring feed on anal secretions from their parents, which provide both nutrition and starter doses of the wood-digesting gut microbes that will eventually let the youngsters eat their way into homes of their own.

Termites are “nothing but social cockroaches”, Schal says. Various roaches have some form of social life, but termites go to extremes. They’re eusocial, with just a few individuals in colonies doing all of the reproducing. In extreme examples, Macrotermes colonies in Australia can grow to 3 million individuals with only one queen and one king.

After several years of debate, the common names committee of the American entomologists’ organization voted it was time to switch to the new view of termites. At a February meeting of the society board, there was no objection.  The common names of individual termite species, of course, will remain as something-something “termite.”

Considering whether to demote a whole order of insects is an uncommon problem, says Whitney Cranshaw of Colorado State University in Fort Collins, a longtime member of the society’s naming committee. “Probably some of us, including myself, didn’t want to make the change because we liked it the way it was”, he says. Termites and cockroaches as separate orders were easy to memorize for the undergraduates he teaches.  Yet, he voted yes. “It’s what’s right.”


Caterpillar defense against beetles

This video says about itself:

Watch this caterpillar fling its beetle attacker through the air

23 February 2018

Hornworm moth larvae have several tricks to defend themselves against predators. Learn more here. And here.