Clams are bivalve mollusks with two equal halves of a shell linked by a ligament as their shelter and a soft body. The two halves of the shell is held together by a front and back adductor muscles. The curved growth lines that are parallel to the outer edges represent the successive additions of new shell material. This material is inorganic minerals extracted out of the ocean, primarily calcium carbonate, the same substance that limestone, marble, and eggshells are made of. Close relatives to clams are mussels and oysters. There are over 12,000 known species of clams. If a clam is not harvested or scavenged they can live to 33 to 36 years on average. They survive mainly on plankton. Plankton are a group of organisms that live in large bodies of water that cannot swim against a current. A clam inhales water through its siphon (tube-like structure) from its surroundings, for oxygen, and for food. Their gills filter the water and sweep food to the mouth. To protect themselves clams burrow down in the mud or sand using their foot. They can burrow more than 11 inches deep. Clams actually live in the sand upside down. The mouth of the clam is next to the foot at the bottom whereas the anus is at the top with the siphons. Clams do not have noses, ears, or eyes, they therefore cannot smell, hear, or see. Clams live a fairly simple and straightforward lives. They have 2 goals in life: to eat, and to reproduce, hence the phrase “happy as a clam”.
蛤仔就是蜆啦，不同地方的人有不同的叫法，但都是美味絕頂的美食。已知的蜆類大約有12000種，住在淡水的蜆大約有500種，這個組織的龐大真的有點驚人，還未算到蜆的表親青口和蠔等等，它們就是人材濟濟，行路用腳仔。蜆在沙上走路時腳和嘴巴都在下方，反而頭頂是用作解決的屁屁，還有兩條水管來吸水又噴水，論外型結構有點像宇宙大王，身為蜆，生存之道非常簡單，有得吃有得生兒育女已心滿意足，因此外國人有一句說話：「happy as a clam」，其實世事又何需過份執著呢施主。