A Clockwork Naturalist

ScienceDaily (Oct. 4, 2011) — A study into the muscle development of several different fish has given insights into the genetic leap that set the scene for the evolution of hind legs in terrestrial animals. This innovation gave rise to the tetrapods — four-legged creatures, and our distant ancestors — that made the first small steps on land some 400 million years ago. [full story]

(Credit: Cole et al., PLoS Biology, DOI: 10.1371/journal.pbio.1001168)

From Science Daily:

April 14, 2011 - Remote lochs along the west coast of Scotland are turning up new evidence about the origins of life on land.

A team of scientists from the University of Sheffield, the University of Oxford and Boston College, who are exploring rocks around Loch Torridon, have discovered the remarkably preserved remains of organisms that once lived on the bottom of ancient lake beds as long as a billion (1,000 million) years ago.

These fossils illuminate a key moment in the history of evolution when life made the leap from tiny, simple bacterial (prokaryote) cells towards larger, more complex (eukaryotic) cells which would make photosynthesis and sexual reproduction possible. The findings are reported in the journal Nature. [full story]

Photo credit: Oxford University/Martin Brasier

From Science Daily:

• Researchers from China, Leicester and Oxford have discovered a remarkable fossil which sheds new light on an important group of primitive sea creatures.
• The 525-million-year-old fossil belongs to a group of tentacle-bearing creatures which lived inside hard tubes. Previously only the tubes have been seen in detail but this new specimen clearly shows the soft parts of the body including tentacles for feeding.
• Details of the discovery have just been announced in the journal Current Biology.
• [full story]

What other mysteries of the deep have we tackled, this week?

Unknown Animals Nearly Invisible, Yet There

• Bryozoans (moss animals) are a group of aquatic invertebrates that are found in great variety throughout the world, with well over 100 species in Sweden alone. Yet little is known about them. Researchers at the University of Gothenburg have now studied Swedish bryozoan species using DNA techniques.
• …When Bryozoa were discovered in the 16th century, they were regarded as plants. Later on they were found to have a nervous system, muscles and an intestinal system and were classified as animals. On their own, bryozoans are barely visible to the naked eye, but like coral animals all bryozoans build colonies that reach several centimetres in size and some species build colonies of over 30cm
• [full story]

Shallow-Water Shrimp Tolerate Deep-Sea Conditions

• By studying the tolerance of marine invertebrates to a wide range of temperature and pressure, scientists are beginning to understand how shallow-water species could have colonised the ocean depths.
• “Many deep-sea species have close relatives living in shallow, relatively warm water, but how shallow-water species were initially able to cope with the huge hydrostatic pressures of the deep ocean is poorly understood,” explained Dr Sven Thatje of the University of Southampton’s School of Ocean and Earth Science (SOES) based at the National Oceanography Centre, Southampton
• To address these issues experimentally, Thatje and his collaborators turned to a model species, the variable shrimp (Palaemonetes varians). The species is native to Western Europe and lives in shallow, brackish habitats. It tolerates low oxygen conditions and wide fluctuations in temperature and salinity, and has potential for commercial aquaculture.
•  ”P. varians is closely related to deep-sea shrimp species living around hydrothermal vents — ‘black smokers’ — in the Atlantic, making it an excellent case for comparison with these deep-living shrimps,” said Andrew Oliphant, lead author and PhD student at the graduate school at the National Oceanography Centre, Southampton.
• The researchers collected variable shrimps from Lymington salt marshes (England) and from Bay of Mont Saint Michel (France) and acclimated them to life in the laboratory. They then tested the ability of adult shrimps to withstand the effects of various pressure and temperature combinations, measuring both oxygen consumption and behaviour.
• [full story]

Scroll down for bonus horrifying plant news!

Science News, web edition, story rundown:

01. Bats pickier about dinner than previously thought. 02. Leashing dogs has minimal impact on wild carnivore populations in northern California. 03. Proposed fossilized dinosaur heart actually just a clump of sand. 04. Sedentary and active worms evolutionarily distinct. 05. Want to reduce the spread of cane toads? Keep them away from water. [full stories]

B. marinus [kind of looks like my grandpa]

Also, this, from Science Daily:

Rising carbon dioxide is causing plants to have fewer pores, releasing less water to the atmosphere.

“As carbon dioxide levels have risen during the last 150 years, the density of pores that allow plants to breathe has dwindled by 34 percent, restricting the amount of water vapor the plants release to the atmosphere, report scientists from Indiana University Bloomington and Utrecht University in the Netherlands in an upcoming issue of the Proceedings of the National Academy of Sciences.”

[full story]