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

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!!!

TODAY… What are oysters? Biological requirements Oyster reproduction Simple dissection

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

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

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

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)

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

Oyster dissection....

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

Mantle Two fleshy folds of tissue Cover the internal organs Always in contact with the shell but not attached Principal role formation of shell

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

Tentacles Small sensory organs Attached to edge of mantle Used to detect environmental stimuli

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

Digestive gland Produces digestive enzymes

Other parts of the oyster Gonad Heart Intestine Visceral mass Mouth Oesophagus Stomach Anus

Now you can eat your oyster if you want to....

Any questions??? Next up: an excursion to an oyster farm