What do clams eat?

In this brief guide, we will address the query ‘what do clams eat?’. We will also discuss if clams eat fish and how they feed. Other topics will be how clams breathe and if they are safe to be eaten.

What do clams eat?

Clams are omnivores and eat plants and animals, such as algae, zooplankton, phytoplankton and whatever organic matter they may find.

There are over 15,000 species of clams, and sometimes their diet may differ a little. We can name a few of them, like the giant clam, Asian clam, razor clam, soft shell clam, and so on. They mostly live in shallow waters, so they can be protected from waves.

Basically, clams eat suspended particles in the water. They have siphons for inhaling and exhaling water in a filtering manner, so when food passes through their gills it gets stuck in a mucus that will move to the labial palps, and then to the mouth.

Despite their small sizes, clams can process about 24 gallons of water a day. They can also use this siphon mechanism to move around.

Do clams eat fish?

Clams do not eat fish. However, they will feed on animal particles and debris, and this includes scraps of fish and also fish poop.

Not just from fish particularly, clams will eat products of decomposition from any animal that floats in the water. On the other hand, this type of food won’t help them constitute their body, i.e. their shells.

A clam’s shell is 100% made of protein, and to obtain that they need to feed from microorganisms. Microbes compose about 90% of biomass in the ocean, so saltwater clams don’t have anything to complain about.

How do clams feed?

Clams feed through filtering water with its gills, siphons and mouth. Clams are covered by a two-parted shell, under which you will find its whole system. There it is a pair of gills covered with cilia – and the cilia movements move water in and out the clam, through its siphons. 

The water is loaded with microorganisms, plankton, algae and other organic matters that will pass through the clam’s gills, which produce mucus. 

The food will then be trapped in the mucus and the cilia will transport this food to the labial palps, these flap-like structures that will finally place the trapped food into the clam’s mouth.

Clams have a complete digestive system – as all mollusks do. It has a mouth, stomach, esophagus, intestine and an anus, from which digestive waste leaves the system. This means the food is processed in a way that is quite familiar to humans.

How do clams breathe?

Clams breathe through their gills when siphons take in water. They are mollusks and therefore do aerobic respiration, hence the need to obtain oxygen somehow. 

Clams cannot breathe outside an aquatic environment because they don’t have lungs. Their respiratory system is adapted to breathe underwater, so you will find them both in saltwater and freshwater habitats.

The gills are responsible for exchanging oxygen and carbon dioxide during respiration. Cilia will create a flow of oxygenated water which will make the clam breathe.

Are clams safe to eat?

Clams are safe to eat when they are cleaned and cooked properly. Although people often like to eat clams, oyster and other seafood raw or undercooked, this practice can be dangerous for your health.

When we talk specifically about clams, there is risk in eating it raw because these animals literally feed on microorganisms (among other things). Bacteria can be stored inside the shell or in the clams digestive system, and if you eat it, you can get food poisoning.

A bacterium commonly found in clams is the Vibrio parahaemolyticus. It won’t be dead until the clam is properly cooked, and if ingested by humans it can cause gastroenteritis.

Therefore, prefer to eat clams (or oyster and mussels) after a proper cook. FDA (U.S. Food and Drug Administration) recommends:

  • Boiling them – and after shell is open, continue to boil for about 5 minutes;
  • Place them in a pot with boiling water for 9 minutes;
  • Discard clams that don’t open while cooking;

You can find other recommendations from the FDA here!


In this brief guide, we addressed the query ‘what do clams eat?’. We also discussed if clams eat fish and how they feed. Other topics of discussion were how clams breathe and if they are safe to be eaten.

We hope that this guide was useful to you. If you have any doubts, please don’t hesitate to contact us!





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