Crab Tomalley Safety: Is the Green Stuff in Shellfish Edible?

Crab tomalley, the green gland in shellfish, is a delicacy for some but may contain contaminants that pose health risks, so caution is advised.

Crab Meat(1)

If you’ve ever cracked open a crab and wondered, “What is the green stuff inside of crabs?” you’re not alone.

It’s also likely that you’ve wondered whether you can eat it or not. Again, you’re not alone.

That green stuff is called tomalley. Whether you should eat it or not depends on a number of factors.

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What Is the Green Stuff Inside of Crabs and Lobsters? 

Crab Meat

The tomalley, the green stuff in both crab meat and lobster meat, is a gland that functions like a combined liver and the pancreas. People also call the tomalley the “green gland,” “mustard,” “crab butter,” the green/ brown stuff,” and the “hepatopancreas.”

When you break the shellfish open, you’ll find the hepatopancreas or tomalley inside the body of the fish. In its fresh state, the tomalley’s texture resembles Jello. Once you cook it, the texture firms up. 

It’s a popular addition to soups, sauces, or mixed in with compound butter. Once cooked, the tomalley adds a strong flavor to whatever it’s cooked with, so much so that some people call it “lobster concentrate,” according to Cook’s Illustrated.

For some foodies, the extra strong flavor that comes from the tomalley is why they love it. For others, it detracts from the more delicate flavors of the crab or lobster. Those in the latter camp avoid eating it (or stick with canned crab) because of the strong flavor.

Can You Eat the Green Stuff in Lobsters or Crabs?

Whether you can or should eat the tomalley depends on who you talk to. Some foodies love the taste of the tomalley and consider it a delicacy. 

Other people won’t eat it at all, due to the possibility of it being full of contaminants. The contaminants come from the waters these shellfish live in. 

It’s good to remember this: The liver is designed to remove toxins from the body. By eating the liver (and the pancreas in this case), you eat the toxins that the animal ate. 

The look, taste, and smell of the shellfish isn’t an indicator of safety, according to the Maine Division of Environmental and Community Health (MDECH). A contaminated crab or lobster may look, smell, and taste completely fine and still cause you harm. MDECH goes as far to say that you shouldn’t eat lobster tomalley at all. 

Other fans of the tomalley are a little more generous in their opinions about whether or not you should eat it. L. Eugene Cronin, who once headed the University of Maryland’s Chesapeake Biological Laboratory, had this to say about the safety of eating crab tomalley.

“Crabs taken from open waters I wouldn’t worry about.”

However, shellfish from harbor waters can be more tricky. 

Cooking the muscle tissue in boiling water and eating it is usually okay because the muscle tissue isn’t affected by contaminants in the same way that the tomalley is. 

The New York State Department of Health offers home cooks a warning, however: Throw out the water that the shellfish is boiled in

Boiling cooks out 80% of the contaminants in the shellfish. Those contaminants end up in the leftover water. While that water might taste good as a soup base or sauce, it could be hazardous to your health.

Contaminants That Affect Shellfish Tomalley

You’ll find the largest concentrations of the polychlorinated biphenyls (PCBs) in the tomalley, as well as any metals and dioxin.

According to the Environmental Protection Agency (EPA), exposure to dioxins, which are persistent organic pollutants (POP), comes largely from just a few sources. These include dairy products and shellfish to name but a few of them.

Once they are introduced to the environment, it takes a long time for POPs to break down. These chemicals have been shown to cause numerous health issues, including developmental issues, cancer, and immune system damage. They can also wreak havoc with the hormones in your body.

Additionally, some people have greater susceptibility to these issues than others. Children under the age of 15, as well as women under 50 years old, are more likely to be affected by these chemicals than others.

They should avoid eating crabs in heavily contaminated waters in places like the New York City area. 

Fifteen-year-old boys and men (and older) and women over the age of 50 don’t have as many issues with these chemicals. Eating up to six crabs a week from areas like the Hudson River is okay.

One researcher and professor, John R. McConaugha of Old Dominion University in Norfolk, Virginia, offers a balanced view of eating crabs in potentially hazardous waters. He suggests that crabs’ mobility levels may keep them more free from contaminants. 

Additionally, while the above examples highlight the waters of New York, it’s probably most accurate to say that you should exercise caution when you are considering eating shellfish from waters that have high contamination levels.

Paralytic shellfish poisoning (PSP) represents an additional concern. PSP comes from consuming shellfish that have gotten contaminated by the red tide. Red tide conditions come from a specific kind of plankton, which produces poisons. The shellfish that are most affected by this condition are filter feeders. 

While shellfish like lobsters aren’t filter feeders, they do eat shellfish, like clams, which can be adversely affected by the red tides. In this case, you can eat these lobsters, but should avoid eating the tomalley from them. 

You consider shellfish a favorite culinary delight, then do your health a favor and stick to the muscle meat.


Is the Yellow Stuff in Crabs Poop?

The nicknames for this organ also highlight the different colors of the tomalley. Calling it poop is a misnomer. Yellow is just one of the colors of the gland.

Is There Poop in Crab Legs?

No. It’s all part of the crab’s tomalley.

Do Crabs and Lobsters Have a Tomalley?

Yes. The hepatopancreas is common to crabs, lobsters, and other crustaceans, according to the National Library of Medicine.

When Is Red Tide?

The red tides that cause some of the issues with crab and lobster tomalley occur at different times of the year. These tides also affected different coastal areas in a different way and for a different amount of time.

For example, Californians experience red tides in the early part of the year, usually in February and March, and then again, in the latter part of the summer, usually in August and September. 

Floridians, on the other hand, experience red tide in the latter part of the year, usually between the months of August and December. Those who live in Texas may also have an experience with red tides that differs from other states.

Additionally, the amount of time that red tides last can also vary. Some last only a few weeks. Others last much longer than that. Red tides can also appear and then go away, only to appear again. 

People who live in the coastal areas should heed the warnings about the red tides that are area specific. 

That is, an advisory for California or Texas may be different than one for Florida. If you live in a coastal area affected by red tides, be mindful of any advisories for your area about the red tide, and for safety’s sake, avoid eating the tomalley in shellfish.

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