Shell-swinging snails knock out predators

Date:November 16, 2016

Source:Hokkaido University


Researchers in Japan and Russia have found some snail species that counterattack predators by swinging their shells, suggesting the importance of predator-prey interactions in animal evolution.

Until now, snails were thought to protectively withdraw into their shells when attacked. However, an international research team has found a pair of snail species that use their shells like a club to hit predators and knock them over.

Evolutionary scientists have been questioning how predator-prey interactions affect the evolution of the prey. However, they are yet to resolve whether this interaction induces the diversification of the prey species and its morphological features and behaviours, and if so, why?

Researchers from Japan's Hokkaido University and Tohoku University collaborated with colleagues at the Russian Academy of Sciences to closely study snail species from the genus Karaftohelix in both countries. They observed each species' defensive behaviours against their predator, the carabid beetle, and conducted shell measurements and species comparisons. The team used DNA sequencing to analyse how closely related the species were to each other.

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Turtle shells didn’t evolve for protection, study claims

JULY 17, 2016

by Chuck Bednar

While modern-day turtles rely upon their shells as protection from predators, that wasn’t the primary reasons that the reptiles’ bone-based outer casing originally evolved, researchers from the Denver Museum of Nature and Science have revealed in a newly-published study.

Rather, the broad ribbed proto shell found on the earliest partially shelled fossil turtles was an adaptation designed to help the creature burrow underground, not protect itself from becoming lunch for an aggressive carnivore, an international team lead by Denver Museum paleontologist Dr. Tyler Lyson reported in Friday’s edition of the journal Current Biology.

“Why the turtle shell evolved is a very Dr. Seuss-like question and the answer seems pretty obvious – it was for protection,” Dr. Lyson explained in a statement. “But just like the bird feather did not initially evolve for flight, the earliest beginnings of the turtle shell was not for protection but rather for digging underground to escape the harsh South African environment where these early proto turtles lived.”

These digging adaptations helped facilitate the movement of turtles into aquatic environments early on in the creature’s evolutionary history, and probably played an key role in helping stem turtles survive the Permian/Triassic extinction event, the authors wrote in their study.

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Beetle bumps inspire bigger and faster water droplets

By Matt McGrath

Environment correspondent

25 February 2016

Scientists have drawn inspiration from the bumpy shells of Namib beetles to improve the collection and transport of water droplets.

Researchers were able to make drops grow six times faster than normal by copying the insects' shell geometry.

Combined with other plant techniques, the team created drops that grew larger as temperatures increased.

The authors say the development could significantly improve water harvesting and electricity generation.

A little drop of water may seem insignificant but the physical processes involved in both the formation and movement of the liquid are essential to operation of thermal power plants, desalination and air conditioning systems.

Condensation is also critical to the more fundamental function of gathering water for human use in dry climates, a growing, global issue.

Researchers have made previous attempts to mimic the remarkable abilities of the Namib beetle, which uses its bumpy shell to draw all the water it needs from periodic, foggy winds in the desert.

The assumption until now has been that the surface chemistry of the beetle's back has been the key - but this new study says that it's actually the physical arrangement and location of the bumps that's critical.

The researchers also aped cactus spines by building their bumpy surface to guide the transport of the harvested drops. The slippery coating of pitcher plants inspired the team to coat the bumps with a smooth lubricant to reduce friction as the drops moved.

According to the study, drops grew six times more quickly on this surface and it was able to collect and transport a much larger volume of water in a short time compared to other materials.

"We experimentally found that the geometry of bumps alone could facilitate condensation," said Kyoo-Chul Park, a postdoctoral researcher and the first author of the paper.

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Atomic bomb radiation in sea turtles’ shells helps scientists figure out their age

by Brett Smith

The atomic bomb may be mankind’s worst-ever invention, but the instrument of destruction does have a tiny consolation for biologists: The bomb’s radiation offers is a trustworthy way to approximate the age, rate of growth, and reproductive maturity of wild sea turtles, according to a new study.

Published in the journal Proceedings of Royal Society B, the study said dating via atomic bomb radiation is more accurate than conventional techniques and may offer new details declines and insufficient recoveries of some endangered sea turtles communities.

“The most basic questions of sea turtle life history are also the most elusive,” study author Kyle Van Houtan, a marine life at Duke University, said in a press release.

In the study, scientists reviewed hard tissue samples from the shells of 36 hawksbill sea turtles archived since the 1950s. The turtles either passed away naturally or were poached for their shells. The scientists worked with various agencies, law enforcement, and museum archives to get the specimens.

The researchers estimated each turtle’s age by comparing the bomb-testing radiocarbon accrued in its shell to background amounts of bomb-testing radiocarbon lodged in Hawaii’s corals. Amounts of carbon-14 greater rapidly in the biosphere from the mid-1950s to around 1970 due to Cold War-era nuclear tests, but have fallen at predictable rates since then, allowing researchers to ascertain the age of an organism by using its carbon-14 content.

The scientists could approximate median growth rates and ages of sexual maturity in their specimens by contrasting their radiocarbon measurements to those of other wild and captive hawksbill populations with known growth rates.

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The topsy-turvy world of the tortoise: a smaller shell helps them to walk tall

JAMIE MERRILL

Sunday 04 January 2015

When it comes to housing, every little helps. And for a tortoise, the bigger the shell, the larger the animal, and the more able the fiercely territorial land-dwelling turtle is able to fight off rivals. Predators, droughts and even food shortages can be kept at bay. This accepted evolutionary narrative has been turned on its head, however, with the revelation that larger tortoises are less adept at righting themselves when they are flipped on to their backs.

Scientists have long known that if you upturn a tortoise, it will find its feet again, thanks to a clever combination of shell shape and leg and neck manoeuvres, but according to a new study, larger Hermann tortoises found in the Mediterranean are less capable of finding their feet than their smaller, more nimble relatives.

Self-righting is a serious business for armoured animals, including ocean-going turtles and cockroaches, because they often spend time in rocky areas and are liable to get stuck on their backs, legs flailing. However, it's an even deadlier matter for the Hermann tortoise, which is often overturned by belligerent males during fights over breeding grounds.

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Increasingly acidic oceans threaten world's mussel populations

Mussel shells could become more brittle as climate change causes acidity of world’s oceans to rise, scientists have warned

Press Association

Wednesday 24 December 2014 06.00 GMT

The world’s mussel population could be under threat as climate change causes the oceans to become more acidic, scientists have warned.

Mussel shells become more brittle when they are formed in more acidic water, Glasgow University has reported in the Royal Society journal Interface.

Carbon dioxide in the atmosphere causes the oceans to become more acidic and reduces the concentration of the minerals mussels need to generate their shells, according to scientists.

However, they also found that mussels may have an in-built biological defence mechanism which boosts shell development when water temperatures rise by 2C.

Dr Fitzer said: “What we’ve found in the lab is that increased levels of acidification in their habitats have a negative impact on mussels’ ability to create their shells.

“We worked with colleagues in our School of Engineering to examine the toughness of the shells of the mussels in the more acidic water against those in control conditions.

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How Turtles Got Their Shells: Fossil of Extinct South African Reptile Provides Clues

May 30, 2013 — Through careful study of an ancient ancestor of modern turtles, researchers now have a clearer picture of how the turtles' most unusual shell came to be. The findings, reported on May 30 in Current Biology, a Cell Press publication, help to fill a 30- to 55-million-year gap in the turtle fossil record through study of an extinct South African reptile known as Eunotosaurus.

"The turtle shell is a complex structure whose initial transformations started over 260 million years ago in the Permian period," says Tyler Lyson of Yale University and the Smithsonian. "Like other complex structures, the shell evolved over millions of years and was gradually modified into its present-day shape."

The turtle shell isn't really just one thing -- it is made up of approximately 50 bones. Turtles are the only animals that form a shell through the fusion of ribs and vertebrae. In all other animals, shells are formed from bony scales on the surface; they don't stick their bones on the outsides of their bodies.

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Hermit Crabs Socialize to Evict Their Neighbors

ScienceDaily (Oct. 26, 2012) — Social animals usually congregate for protection or mating or to capture bigger prey, but a University of California, Berkeley, biologist has found that the terrestrial hermit crab has a more self-serving social agenda: to kick another crab out of its shell and move into a larger home.

All hermit crabs appropriate abandoned snail shells for their homes, but the dozen or so species of land-based hermit crabs -- popular terrarium pets -- are the only ones that hollow out and remodel their shells, sometimes doubling the internal volume. This provides more room to grow, more room for eggs -- sometimes a thousand more eggs -- and a lighter home to lug around as they forage.

But empty snail shells are rare on land, so the best hope of moving to a new home is to kick others out of their remodeled shells, said Mark Laidre, a UC Berkeley Miller Post-Doctoral Fellow who reported this unusual behavior in this month's issue of the journal Current Biology.

Continued:  http://www.sciencedaily.com/releases/2012/10/121026125131.htm

Panic in Devon as 800 are cut by razor shells

THOUSANDS of holidaymakers were evacuated from three packed beaches yesterday after 800 people suffered freak cuts from the shells of razor fish.

Paignton, Preston and Broadsands beaches in Torbay, Devon, had to be closed and roads to the beaches were sealed off. Coastguard officials, police and even deckchair attendants were drafted in to tend the injured, with 30 people taken to Torbay Hospital. Torbay council said the incident was "classed as a total emergency operation". A fleet of 14 ambulances, including an air ambulance, were called into action.

All the injured suffered cuts to their feet after standing on the shells of dead razor fish, which were buried in the sand. Because of the hot weather there were extreme tides which had caused the sea to go out much further than usual. It meant that people were paddling in areas that were not usually accessible, the Brixham Coastguard said.

Continued:  http://www.independent.co.uk/news/panic-in-devon-as-800-are-cut-by-razor-shells-1170707.html