Safety in Numbers? Not So for Corals
"The last 10 thousand years have been especially beneficial for corals. Acropora species, such as table coral, elkhorn coral and staghorn coral, were favored in competition due to their rapid growth. This advantageous rapid growth may have been attained in part by neglecting investment in few defenses against predation, hurricanes, or warm seawater. Acropora species have porous skeletons, extra thin tissue, and low concentrations of carbon and nitrogen in their tissues. The abundant corals have taken an easy road to living a rich and dominating life during the present interglacial period, but the payback comes when the climate becomes less hospitable.”
University of Hawaii (2013, November 15). Safety in numbers? Not so for corals. ScienceDaily.
Silly Acropora cut corners in Evolution class.
Myths and Misconceptions About Evolution
Great stuff from the TED-Ed folks! Evolution is much more nuanced and complex than usually presented, but it’s also that much more amazing.
Imagine how many Nudibranchs I’d see.
Or mimic octopuses.
C’mon evolution, catch up!
NB. Yes, I understand the devolution argument. If you tell me the gilled organism I evolved from can name nudibranchs by latin name, I will accept that argument. However, I want the cognitive capacity to appreciate the privilege.
Conus sea snail shell evolution, another gem from Wired’s Best Scientific Figures of 2012. There’s some real artistic gems hidden in research papers.
Peek inside a Leatherback Turtle’s (Dermochelys coriacea) mouth: How to eat jelly fish when your mouth is an exquisitely evolved jellyfish deathbed.
We know turtles like to eat jellyfish, and the Leatherback likes them most of all. However, this is the biggest turtle, consuming a prey that extremely low nutritional value, therefore it has to nom on a lot of them. As it does so, it takes in saltwater as well. The jellies and the saltwater get stored in the esophagus.
What happens next you ask? Is it to do with the horrific looking backwards facing spines that don’t look comfortable in anything’s mouth?
But of course! Because that is the beauty of evolution, the refined logic of adaptation.
The muscles of the esophagus squeeze the seawater out of the mouth and the spines, which get progressively larger down the esophagus, hold the jellyfish in place. Once all the water is gone, the jellies are passed into the stomach.
This is one of the many *awesome* characteristics of the leatherback turtle - trawling for jellyfish on this earth for over 90 million year.
Trawling for fish/shrimp (by humans, not leatherbacks), is one of the reasons Leatherbacks are classified as Critically Endangered by the IUCN Red List.
Source: Evolution FB
Matt Walker writes a very interesting article in BBC Nature about the question of why animals don’t appear to have evolved defences against us - a natural predatory force, as they do other predator pressures.
Well, a normally reliable response to predation is to get bigger. Than your predator, preferably. For example: Lions, wolves and orca tend to avoid fully grown, fit buffalo, moose and whales respectively.
However, in the human world we have a saying, “the bigger, the better”, and suddenly being large was no longer a defense, but rather an attraction for the up and coming human predator.
The same went for other defensive ornaments - ivory for elephants, (meaty) claws of lobsters and crabs. Their very defenses became their downfall.
Other responses include becoming poisonous - either by producing toxins, or harnessing toxins produced by microbes. But we are nothing if not ingenious, and have learnt to cut out the bad bits.
In short “we hunt on too grand a scale, with too much ingenuity, targeting the biggest animals.”
“Our arrival and technological history has engendered an enormous change in the evolution of most species on Earth,” says Prof Vermeij, of University of California at Davies who has studied the effects of predators on evolution for more than thirty years.
"In evolutionary terms, we leave our prey with nowhere to go. They have no way to defend themselves and simply cannot respond. And that represents a cataclysmic shift for species on this planet, the implications of which, he adds, we have barely begun to understand."
It is a bit of a “no-shit-Sherlock” situation. Of course nature hasn’t got time to adapt to us. There’s 7 billion of us. What we can do is do better at giving reprieve to some areas of land and sea, to give evolution time to catch it’s breath.
Could life on Earth have begun on land and not in the sea?
A new study, published in PNAS online today argues that the first cells are more likely to have developed in slimy volcanic mud pools, akin to Darwin’s theory that life started in a “warm little pond”.
Recent decades have had Scientists favouring a marine beginning because of the continuous discoveries of life in inhospitable depths. Simple yet hardy bacteria are able to utilize the rich minerals spewing from volcanic vents for chemosynthesis, starting a non-light based food chain and supporting rich hydrothermal vent communities.
Scientists have thought that conditions surrounding these vents could resemble the birth place of cells.
However the new study looked into cellular fluid and found the it is extremely different to ancient ocean water, instead showing a similarity to condensed vapours in volcanic mud pools on land.
Such terrestrial environments boast the high ratios of potassium to sodium found in all living cells. Marine environments, meanwhile, are far too rich in sodium.
"For cells to synthesize proteins—their molecular machines—they need a lot of potassium. Sodium blocks these activities," said study co-author Armen Mulkidjanian, a biophysicist at the University of Osnabrück in Germany.
Cells today rely on complex proteins to pump excess sodium out through their membranes, so the cells can function properly.
The first cells however simply had the luck of the draw. With no complex systems, only rudimentary cellular membranes, these cells simply had to work with the nutrients that were trapped inside.
As a result, the first cells were highly permeable and completely at the mercy of their environments. The ratio of potassium to sodium therefore had to be greater than one to one, in favor of potassium.
But in ancient seawater—as well as in modern seawater—sodium outnumbers potassium 40 to 1.
So the biochemists teamed up with geologists to figure out where these conditions might have occurred between 4.3 and 3.8 million years ago!
The team realized that geothermal fields on land could do the job, particularly the mud pots found in places such as Yellowstone National Park.
"Mud pots are where steam is coming out of the earth and condensing, carrying with it many minerals, including potassium," Mulkidjanian said. "They look like slime coming out of the earth and would make a nice kind of hatchery for the first cells."
Scientists had long ignored mud pots as possible analogs to primordial ooze, because the modern-day versions are swimming in sulfuric acid, a deadly chemical that forms when hydrogen sulfide encounters oxygen in the atmosphere.
"People were scared away by the acidic condition, but Earth used to have very little oxygen in its atmosphere," Mulkidjanian said.
"These anoxic environments were stable over millions of years and were probably conducive to supporting the first life on Earth."
I would like to say something intelligent and meaningful, since this kind of turns everything on it’s head [well that Guinness advert would be wrong now]. So all you’re going to get is ”The Hippopotamus Song [a mud love story]” by Flanders and Swann:-
"Mud, mud, glorious mud, nothing quite like it for
coolingcreating the blood”
Adapted from National Geographic
Happy Darwin Day everybody! Pay homage to the DNA arms race and spend a magical few minutes with Carl Sagan.
Scientists at the University of Western Australia have now sequenced the DNA of a patch of Posidonia oceanica, a seagrass of the Mediterranean Sea, to determine its age. And, as it turns out, some parts are up to 200,000 years old, which easily beats that of the previously-believed record-holder, a Tasmanian plant around 43,000 years old.
How could this be possible? The seagrass, also known as Neptune Grass or Mediterranean tapeweed, grows in massive clumps and is continuously growing new branches and expanding. The seagrass reproduces asexually by cloning, and spreads far and wide so that it can survive even if one particular area becomes depleted of natural resources.
To put this age into perspective, 200,000 years ago, anatomically modern humans were just evolving in Africa, while we only reached “behavioral modernity” around 50,000 years ago.