Thursday, 13 November 2008

The Native European Oster - Ostrea edulis

Ostrea edulis, as we know it, as the native oyster, is a bivalve mollusc that is farmed on an international basis due to it being a highly prized delicacy, ranging from western Europe including the tip of Norway, all the way down to Morocco including, the Mediterranean basin and they are also observed and researched in North America. (FAO Fisheries and Aquaculture, 2008) Japan and Australasia. Within the United Kingdom they are found throughout the coastline but are found in abundance in the Thames, The Solent and Loch Foyle and in our very own River Fal Estuary (Arkive 2008). As like many species it has acquired several names for itself, that often come about from its structure. In this case the flat oyster. It is compromised of two shells which are both different in shape. One being concave the other appears more flat, thus the name. Its two halves (valves) are held together by a muscle called the adductor muscle which contracts to close the shell firmly tight, then relaxes to open. The shell itself is generally pear shaped, but verges on circular and has a scaly hard surface, with off white or creamy brown colour. Which many sources all agree with, on the other hand I found another source has mentioned they tend be greyish in colour. (Fish and fish, 1989). The inner is however of pearly textures consisting of white to blue which is of all opinion .They attach themselves to their habitat by a cement type fixture, where they sit and filter water through their gills sifting out micro algae. They can be very selective, as research has proved that when they were given different species of algae the labial palps can differentiate between these species. Therefore making O. edulis a very special type of suspension feeder. (little and Kicthing 1996).Some of the information I have just relayed has come from a number of sources. Mainly the FAO website which is very detailed and covers many features, statistics, practise and historical background. A must when researching any type of marine life. Another very broad source of information is the Marlin website, which entails taxonomy, longevity, general biology, sensitivity and basic information. Both of which agree widely on many aspects but take a different approach with the layout and presentation of the context. The books I’ve used here are unique in their own way, as they don't hold as much information but are still informative, with only a few differences that I could find.