Fish’n’co – ‘Happy as a clam’ (feat. Ruditapes philippinarum)

The clam is a common name for several globally distributed species of marine and freshwater bivalve molluscs and they typically spend much of their lives burrowed in the sandy or muddy substrate of the seafloor or riverbeds. A clam’s shell consists of two valves (calcareous shell), which are connected by a hinge joint and a ligament that can be external or internal. The ligament provides tension to bring the valves apart, while adductor muscles can contract to close the valves. Clams have kidneys, a heart, a mouth, a stomach, and a nervous system, but no eyes, ears or noses. Like all filter feeders, clams are an important part of the ecosystem, feeding on phytoplankton and helping to maintain the water quality in their surrounding environment. One method by which they help maintain water quality is through the removal of excess nitrogen by incorporating it into their tissue and shells as they grow. They also act as a food source for many animals and are a staple part of the diet of many birds, seals, sea otters and octopus’ species. An interesting fact about the clam is that some polar species are thought to be among the longest-lived non-colonial animals in the world (Wanamaker et al. 2008)

Clams have two main goals in life; to eat and to reproduce. They reproduce sexually one to two times per year and the female clam can release millions of eggs in a single spawning (Davis and Chanley, 1956). Perhaps this simple approach to life would lead many to think that this is where the phrase as ‘happy as a clam’ originates from. Instead, this phrase is thought to have originated in north-east USA in the 19th century where shellfish was a prominent component of the human diet. It is believed the phrase was used to highlight the happiest time of a clam’s day – during high tide, the time of the day when the molluscs were safe from predators!

Ruditapes philippinarum, more commonly referred to also as the Japanese carpet clam or manila clam was initially cultured from wild Asian populations. Due to its commercial value, it has since been introduced to many parts of the world. In European waters, spat supply is based both upon hatchery products as well as harvested wild seed. The availability of wild seed is a result of the invasiveness pattern of this species in areas where it was formerly cultured using hatchery-produced spat ( R. philippinarum is found in coastal sediments ranging from the inter-tidal zone to the shallow sub-littoral zone, typically reported as being present in the lower shore (Zhuang et al., 1981). Some advantages of culturing this species of clam include its high commercial value, simple spawning condition, toleration of environmental stress, short life stages and fast growth (Moosapanah 1996). R. philippinarum has become a recent candidate for polyculture (, a method shown to help reduce some of the environmental impacts of aquaculture (Martinez-Porchas and Martinez-Cordova 2012).


Wanamaker, A.D., Heinemeier, J., Scourse, J.D., Richardson, C.A., Butler, P.G., Eiríksson, J. and Knudsen, K.L., 2008. Very long-lived mollusks confirm 17th century AD tephra-based radiocarbon reservoir ages for North Icelandic shelf waters. Radiocarbon, 50(3), pp.399-412.

Zhuang Q Q, 1964. Studies of Chinese species of Veneridae (Class Lamellibranchia). Studia Marina Sinica. 43-106.

Moosapanah, Gholam Reza, 1996.. Oregon State University. ProQuest Dissertations Publishing. 9634066.

Martinez-Porchas, M., & Martinez-Cordova, L. R. 2012. World aquaculture: environmental impacts and troubleshooting alternatives. TheScientificWorldJournal, 389623.

Photo: Malcom Storey/