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http://www.youtube.com/watch?v=lBgh_YmY4lU amazing habitat (polyps coral) http://www.youtube.com/watch?v=cbN161yBBGA coral reefs in danger as people fish for rare species http://www.youtube.com/watch?v=AA42hW4nHbg&feature=related coral reef close up – very diverse CORALS most simple group for terminology on our specification! http://www.youtube.com/watch?v= wsaZ8-I7akg corals spawning http://www.bbc.co.uk/nature/life/A nthozoa#p00n6tnv spawning! CNIDARIA/CORALS You could learn lots about them! But we only have to learn septa and colonial/solitary Phylum: Cnidaria: (formerly called Coelenterata) Class: Anthozoa: (corals) Hydrozoa: (hydroids) Scyphozoa: (jellyfish) Sub-Classes: Zoantharia: Rugosa (extinct) Tabulata (extinct) Scleractina (reef building, still exist part of the Zoantharia). The polyps are solitary or colonial. The soft parts are divided into 6, 8 or more. Often have a bilateral symmetry. Marine. http://www.bbc.co.uk/nature/li fe/Anthozoa#p00ms41r corals and plants relationship “Bag of guts” MORPHOLOGY: Corals are usually sack shaped (widest at the top) which contained the MOUTH narrowing at the base where it was attached. The body structure is simple with a hard calcite outer layer and an inner body cavity. http://www.bbc.co.uk/nature/life /Anthozoa#p00dhm3h SOFT PARTS: The body cavity is divided into small segments by RADIAL MESENTERIES (partitions) which give it stability and strength and provide more efficient feeding. Outer Layer = ECTODERM Inner Layer = ENDODERM The inner body cavity = COELENTERON (ENTERON) WE DON’T SEE ANY OF THIS IN FOSSIL FORM! Mesenteries increase surface area and help digestion of food. The MOUTH is usually towards the centre and has a number of functions: 1. Takes in food. 2. Allows discharge of waste. 3. Discharge of larvae. The mouth is surrounded by retractable tentacles, which have stinging organs on them. Some corals show a bilateral symmetry but more commonly show radial symmetry solitary Coralite is conical in shape. The skeleton grew upwards from a narrow base. Plenty of space to grow = ROUNDED shape The whole structure can be straight or curved (horn shaped). CALICE appears like a depression and in this can be seen a central region called the AXIAL REGION. The ends of the SEPTA can also be seen sometimes. A COLUMELLA may be present in the centre (rod like) Colonial/Compound Corals Lots of them a colony Often short of space for growth Polygon shaped Competition for food etc http://www.bbc.co.uk /programmes/p00msn 8q coral turf wars! Colonial/Compound Corals In colonial corals there are often a large number of septa. TABULAE: These represent former levels of the calice floor, secreted by the polyp to seal off the lower area of the corallum. They are best seen if longitudinal sections are cut. Colonial/Compound Corals They are made up of varying numbers of individuals each called a corallite. They are subdivided based on the relationship between the corallites: FASCICULATE: The individuals are not closely touching. Fasciculate corals can be further sub divided: DENDROID: They branch irregularly. PHACELOID: If the corallites are parallel to each other. Colonial/Compound Corals MASSIVE: All the corallites are in contact. These are also further sub divided: CERIOID: Polygonal corallites in cross section and they have a clear dividing wall. ASTRAEOID: The walls are absent. Mode of life and palaeoenvironment (Index Fossil) Sessile apart from when in larval stage. Benthonic and fixed. lived in warm (22 - 29ºC ideally 25ºC) tropical. Shallow seas ideally <25 m continental shelf. They like clear water with little sediment. Well oxygenated, high energy. Typically found in carbonate rocks especially in the Carboniferous. Scleractinian corals Middle Triassic to Recent. Most important in the Jurassic. Not very important in the Cretaceous (but can be found in the Chalk) In the present they form important reef building animals in the tropics and sub tropics around ocean islands and east coasts of large landmasses. http://www.bbc.co.uk/news/world-europe-16026961 insurance policy for the future http://www.bbc.co.uk/programmes/p 00msl9l colourful at night!