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Coral Reefs

Coral Reefs. Location of Reefs. Found between 30°north and 30°south Reason: coral reefs do not thrive in areas where the surface temperature is below 70°F Two areas of coral reefs Continental Oceanic Indian Pacific. Types of Reef. Barrier Offshore, and separated by a lagoon Atol

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Coral Reefs

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  1. Coral Reefs

  2. Location of Reefs • Found between 30°north and 30°south • Reason: coral reefs do not thrive in areas where the surface temperature is below 70°F • Two areas of coral reefs • Continental • Oceanic • Indian • Pacific

  3. Types of Reef • Barrier • Offshore, and separated by a lagoon • Atol • Deep ocean, volcanic foundations • Fringing • Simplest – built upwards and outwards in shallow seas, beside islands or continents

  4. Formation of Reefs • Built of entirely marine plants and animals • Material is calcium carbonate: limestone derived from the surrounding waters by reef organisms • Reef is a veneer on which new limestone can attach • The sea level limits the upward growth of the reef • Reefs have only existed for a relatively short amount of time in geological terms

  5. Corals • Both living and dead, they form a framework • Solid and unyielding or soft but firmly attached • Form into mounds, plates, branches or crusts • Are coelenterata along with jellyfish and sea anemones • Special prey catching cells - nematocysts • Colonial – single founder individual, dividing to replicate itself over and over again • Zooxanthellae – tiny single celled photosynthesising plants amongst within coral tissues

  6. Plankton • Too small to be seen, and are transparent ZOOPLANKTON • Gelatinous • Some predators, others produce fine mesh for collecting food, some produce mucus ‘house’ PHYTOPLANKTON • Microscopic in size • Photosynthetic

  7. Algae and Seagrasses • Important biological component of coral reefs • 500 species of seaweed and 12 species of sea grasses in the Great Barrier Reef • All marine flowering plants are known as sea grasses • They have male and female parts • Able to pollinate while submerged in sea • Known as hydrophilous pollination • Non-flowering marine plants are known as algae/seaweed

  8. Sponges • Important role in complex structural processes • Chemically digest the limestone skeletons which go on to form the base of the coral reef • Efficient ‘vacuum cleaners’ • Filter out bacteria, detritis and coral mucus

  9. Marine Worms • Brightly coloured, voracious jaws, well developed eyes • Exist within dead coral skeleton • Bore by chemically dissolving coral • Range from microscopic to several cms in length

  10. Molluscs • 4 major groups • Gastropods – seasnails, slugs • Bivalves – oysters, scallops, clams • Cephalopods – octopus, squid • Chitons – molluscan equivalent of terrestrial armadillo • Soft bodied with a hard outer shell • Found in coastal ‘zones’

  11. Crustaceans • Reefs abound with brilliantly coloured crustaceans • Most live in hiding only come out at night to feed • Exoskeleton gives protection • Female lays eggs which remain attached until developed • Live in permanent symbiotic relationship with coral • Provides shelter, protection and food

  12. Bryozoans • Hidden areas of reef encrusted with moss-like bryozoans • Often most dominant life form • Grow on rigid surfaces, moving objects or are free living in the water

  13. Echinoderms • Most conspicuous creatures on the reef • E.g. sea urchins, starfish, cucumber • 6000 species • Almost all bottom dwelling • Have a sessile lifestyle, and are suspension feeders, but some are carnivorous

  14. Ascidians • Filtering water bags • E.g. seasquirts • Two important roles: • Feed in the water around the reef and keep it clean • Concentrate the plankton in the water making it available for other animals • Sessile lifestyle fixed firmly to substrate • Cilia set up water current to allow filter feeding

  15. Fishes • Diverse range • Many have evolved with the coral • As size of fish increases the number of species increases and the number of individuals decreases • Many territorial • Adapted in shape and behaviour depending on food source

  16. 4 types: • Grazers • Plankton feeders • Mollusk, crab, shrimp feeders • Predators

  17. Dangerous Animals on the Reef • Many use chemical defences • Bacterial attack can be countered by development of bacteriocides • Mechanical and chemical offensive weapons also abundant

  18. Example – Portuguese Man o’ War • Have toxin loaded cells • And needle sharp barbs at end of coiled spring

  19. Example –Sea Urchins • Have sharp spines • Can have a coating of venomous mucus

  20. Example –Sea Snakes • Have small fangs • But with deadly venom • Are more dangerous than land snakes

  21. Example –Puffer Fish • Puff up and produce strong poison • Is called tetrodoxin

  22. Example –Moray Eels • Have large, hooked, razor sharp teeth

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