27th Aug 2013

Living Fossils

Located in Hamelin’s Pool, a shallow area of Shark Bay in Western Australia, these odd formations aren’t rocks—they’re stromatolites, and they were built over millennia by single-celled cyanobacteria (also known as blue-green algae). 4,000 to 6,000 years ago, a huge bank of seagrass began to block the tidal flow into Hamelin’s Pool, which meant that the water became twice as salty as the open ocean. Animals like snails and chitons that would usually feed on the algae couldn’t survive, so the blue-green algae began to flourish. Gathered in colonies, they trapped sediment with their sticky surface coatings. This sediment reacted with calcium carbonate in the water and formed limestone, essentially creating a living fossil—this limestone is alive, its top surface layer teeming with active cyanobacteria. The limestone builds up slowly at a rate of about 1mm per year. The stromatolites in Shark Bay are estimated to be between 3,000 and 2,000 years old, but they’re similar to life forms in Precambrian times, 3.5 billion years ago, at the dawn of complex organisms. There are over 50 kinds of cyanobacteria in Shark Bay, and one is thought to have descended from an organism that lived nearly 2 million years ago, making it a part of one of the longest biological lineages.

(Image Credit: 1, 2)

This post has 3,851 notes
  1. almostinfamous reblogged this from jtotheizzoe
  2. chuckcharlesworth reblogged this from filthy-hippie-vibes
  3. iemongel reblogged this from lostbeasts
  4. paperchicken reblogged this from neurotryptiline
  5. paintmeanything reblogged this from infinity-imagined
  6. whitehousepost reblogged this from infinity-imagined
  7. monniexx reblogged this from sciencesoup and added:
    These were beautiful, I went and saw them yesterday 😌😌
  8. c-ology reblogged this from culturehunt
  9. archaeo555 reblogged this from sciencesoup
  10. thatmakesalmostnosense reblogged this from thatonewannabechef and added:
    They’ll mutate and attack ships!!
  11. brave--as--a--noun reblogged this from afro-dominicano
  12. drooljewel reblogged this from sci-universe
  13. bendoughertycincinnati reblogged this from infinity-imagined
  14. radioactivephoenix reblogged this from meaningfulpatterns
  15. margealton reblogged this from cabinet-de-curiosites
  16. adventuresadrenaline reblogged this from jtotheizzoe
  17. papermark reblogged this from infinity-imagined
  18. btw-idk reblogged this from kegelgod
  19. theterribleseamonster reblogged this from essentialnaturalism
  20. youknowmeasred reblogged this from jtotheizzoe
  21. duckadoo reblogged this from sciencesoup
  22. stormgeddeon reblogged this from afro-dominicano
  23. nickshaw610 reblogged this from lostinthecoldestwinter
  24. katterrena reblogged this from cabinet-de-curiosites
  25. princessmeanypants reblogged this from cabinet-de-curiosites
  26. ozilot reblogged this from cabinet-de-curiosites
  27. cabinet-de-curiosites reblogged this from lostinhistory
  28. bartlmiller reblogged this from sci-universe
  29. littlemisswaffles reblogged this from oneofdaoddones
  30. skraitouttacompton reblogged this from quasiflexuralthrusting
  31. dashboardpears reblogged this from lostinhistory
  32. theidofdav reblogged this from lostinhistory
  33. annabel-lee29 reblogged this from lostinhistory
  34. kitteh-with-a-candlestick reblogged this from lostinhistory