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Published byCameron Black Modified over 8 years ago
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PROGRAM OVERVIEW Class visit 1: Introduction and biology of oysters Excursion 1: Tour of local estuary and oyster processing facility Class visit 2: Oyster production Excursion 2: The business of oyster farming Class Visit 3: Improving operations Excursion 3: Harvesting and marketing
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PROGRAM OVERVIEW You will see all steps in the oyster growing process Local oyster farmers are sharing their time and knowledge with you! You SHOULD all taste an oyster!!!
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TODAY… What are oysters? Biological requirements Oyster reproduction Simple dissection
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WHAT ARE OYSTERS? Bivalve molluscs True oysters belong to the family Ostreidae which includes a number of edible oysters Highly calcified shell surrounds a soft body Found in marine and brackish water
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Biological requirements Filter – feeders Can filter up to 5L of water an hour Feed on phytoplankton (microscopic plants) that they filter from the water column using their gills
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Sydney Rock Oysters Sydney Rock Oyster Saccostrea glomerata is an oyster species endemic to Australia and NZ Sydney rock oysters are capable of tolerating a wide range of salinities (halotolerant) Usually found in the intertidal zone to 3 metres below the low water mark
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Pacific Oysters The Pacific Oyster Crassostrea gigas are an introduced species Average length is 8 to 15cm Maximum size 30cm (some exceptional specimens reach 40cm)
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Oyster reproduction Broadcast spawners - eggs and sperm are released into open water where fertilisation occurs The eggs develop into free swimming planktonic larvae The larvae swim in estuarine and coastal waters for up to 3 weeks The larvae then cement themselves onto a clean substrate and metamorphoses into adult form
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Oyster dissection....
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Oyster external anatomy Umbo – pointed end of the oyster, is the oldest part Valves – the two shells of the oyster, made up of 98% calcium carbonate Hinge – area formed by the joined valves AnteriorPosterior
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Mantle Two fleshy folds of tissue Cover the internal organs Always in contact with the shell but not attached Principal role formation of shell
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Gills Largest organ in oyster Each gill consists of 2 folds of tissue Primary role is respiration Also creates water currents, collects food particles and transports them to the start of the digestive system
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Tentacles Small sensory organs Attached to edge of mantle Used to detect environmental stimuli
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Adductor muscle Muscle responsible for opening and closing the valves The weight of this muscle accounts for 20-40% of the soft tissue weight of an oyster
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Digestive gland Produces digestive enzymes
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Other parts of the oyster Gonad Heart Intestine Visceral mass Mouth Oesophagus Stomach Anus
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Now you can eat your oyster if you want to....
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Any questions??? Next up: an excursion to an oyster farm
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