SOME TWO BILLION YEARS AGO THE CLOSEST THING TO LIVING REEFS ON OUR PLANET were widespread masses of stromatolites, mounds of cyanobacteria and sediment held together by calcium carbonate they secreted. Before they arose to dominate the seas, the earth was a hellish place. Afterwards, it was a world on the road to the evolution of life as we know it. FOREBODING PLANET Before stromatolites, the planet was largely a worldwide ocean, with landmasses no
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Gone diving. Out of touch. Not posting too much new stuff. In the meantime, here’s a re-post that’s terrific: CONSIDER THE TRIANGLE OF DIVERSITY. It wasn’t that long ago (in geohistory terms) that tropical marine life was distributed much more uniformly worldwide than is the case today. The Earth’s landmasses were configured differently and a strong current circled the planet along the Equator, widely dispersing tropical life. So why, today, do many of us have to
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1) THE GENERAL DEFINITION OF SPECIES IS THAT THEY ARE GROUPS OF ORGANISMS that are like each other and can produce offspring with the same traits. While member of a species can sometimes produce hybrid offspring with another species, those offspring should not be able to reproduce. 2) Within each species of gene-directed traits, there are inevitably genetic variations that favor some as environments change and work against others. As succeeding generations adapt to these changing circumstances,
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WHILE THERE ARE NEARLY 70 SPECIES OF SEA SNAKES in the Pacific and Indian Ocean basins, there are exactly none in the Caribbean and tropical Atlantic. Even though sea snakes almost certainly could prosper in the warm Caribbean tropics, their absence is a factor of timing, geography and ocean currents. “WHY ARE THERE NO SEA SNAKES IN THE ATLANTIC? That was the question explored in an article in the journal Bioscience. Also, the article’s title. Unfortunately,
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MY POST IN THE ORIGINS SECTION, “The Far Side of the World: Geohistory & the Triangle of Diversity,” helps explain why we in the U.S. pay much more money and travel much longer distances to dive in the Pacific rather than the Atlantic/ Caribbean. ICE AGE EXTINCTIONS At one time ocean life was uniformly distributed worldwide along the Equator, but the movements of continents and the rise and fall of sea level ensured that many
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