Happy as a clam is a colloquial expression – a simile to describe a happy person. If a person is said to be ‘as happy as a clam at high water’ it means that they are content and satisfied. 

What is the origin of this expression? The website The Phrase Finder believes that it may have originated in America in 1833 in the book The Harpe’s Head – A Legend of Kentucky – “It never occurred to him to be discontented … He was as happy as a clam.” General Robert E Lee used the phrase too in the 1830s.

Clams are said to be ‘happiest’ when the tide is high because they are then hidden from view, and hidden from their predators, such as gulls. When the tide is low, birds can see the clams in the sand – and will eat them.

It is also thought that clams, when closed, look like they are smiling. 

The Clam is a marine (saltwater) bivalve mollusc with a thick shell called a mantle. Its shell is actually two equal-sized calcareous valves connected with a flexible adductor muscle. The shell can open and close. Bi-valve means two valves (or two shells). The Clam has a mouth, a heart, kidneys, a stomach, and a nervous system. 

It lives in the outer edges of coral reefs close to shore. It is sessile – it does not move. It attaches itself to rocks or dead coral. 

Location of photographs: Aquarium de Paris-Cinéaqua, France

Photographer: Martina Nicolls

Martina Nicolls: SIMILAR BUT DIFFERENT IN THE ANIMAL KINGDOM