Lobster Cannibalism: 6 Eye-Opening Reasons Why It Happens

Lobsters are beautiful creatures. They use different mouth parts to catch, tear, and grind their food. Although the lobster mouth is small, their stomach has three teeth that help break down the food.

For a long time, Marine scientists have considered lobsters to only eat dead particles, but now we know more. They eat about 2% of their body weight daily and have a varied diet. 

What’s interesting, though, is the idea of “lobster cannibalism.”

As a marine biologist, I’ve researched this at the Whitney Laboratory for Biosciences in Florida. Then, presented a full article about Lobster cannibalism, but let me start with a quick explanation.

Lobsters are cannibals, which means they sometimes eat younger lobsters. This doesn’t usually happen, but things like climate change, warmer water, having too many lobsters, overfishing, not enough food, or the fact that other lobsters are nutritious can make them do it. In tanks or aquariums, lobsters might eat each other if they don’t get the right food.

However, that’s not the full story.

Below, I’ll explain more about lobster cannibalism and whether other crustaceans do this too. We’ll also look at what lobsters eat. Keep reading!”

What is Lobster Cannibalism?

Lobsters naturally eat crabs, clams, mussels, starfish, and other small crustaceans.  However, they can sometimes become cannibalistic, eating other lobsters to satisfy their hunger. This behavior is known as lobster cannibalism.

Defining Lobster Cannibalism & Explaining When and Why it Occurs.

When lobsters bite or eat other lobsters to satisfy their hunger, it is called lobster cannibalism. 

However, be aware that this is not their natural behavior. Certain factors compel them to engage in cannibalism (which I will discuss later). 

Let me share my own experience of how lobster cannibalism occurs in captivity.

 At the Pritzker Marine Biology Research Center, located at New College of Florida, my research focused on how baby lobsters eat each other during their developmental stages.  I used an aquarium, placed a waterproof video camera inside, tethered one lobster, and let others swim freely.

 At night, a larger lobster pushed the smaller one into a corner until a leg came off, then devoured the smaller lobster within seconds (I did not feed them intentionally for my research purpose ) don’t do it unnecessarily on your own.

So, if still wonder what are lobster cannibals, what do lobsters eat in the wild, I share the experiment on lobster cannibalism, conducted by Noah Oppenheim a University graduate of Maine University.

In the summer off the coast of Maine, the ocean holds a deadly secret.

Lobsters, carpeting the sea floor here and there, are hungry.

At the same temperature in 2012, off the coast of Maine, a marine biologist from the University of Maine, Noah Oppenheim, researched lobster cannibalism.

He tied a juvenile lobster to an infrared camera. He dropped it into the murky water, 20 feet (6 meters) deep, to observe which predators (he expected cod, herring, or groundfish commonly found there) would come and feast on the lobster.

Initially, when scientists placed cameras in 1992, they found that the primary predators of lobsters were fish. They also knew that lobsters in captivity ate each other, but would they show the same behavior in the wild?

Noah Oppenheim observed the situation. What occurred over the hours provided proof of lobster cannibalism.

A large lobster arrived, grabbed the juvenile within seconds, tore off its claws, and devoured it.

According to Noah, “It’s very gruesome, but this process is occurring out in the wild every night.”

Why Do Lobsters Eat Each Other?

Lobsters eat each other due to climate change, overfishing, limited food sources, and the nutritional value found in other lobsters. All of these factors are triggers to the eerie phenomenon of lobster cannibalism.

1. Warming Waters

When water temperatures rise, lobster offspring increase and grow more rapidly and become more fecund. Lobster cannibalism is a result of higher densities along the Maine coast.

Oppenheim believes that rising temperatures are the cause. Over the past few decades, the average temperature of coastal waters has been 50.7 degrees Fahrenheit and is still increasing. The previous average was 47.6 degrees.

Lobsters are well-known for their territorial fights, with the winner gaining the best shelters and preferential mating rights. Therefore, it’s common to see lobsters missing claws, as they attack each other when placed together in confined spaces. If we talk from an aggressive point of view, Norwegian lobster is a very bad cannibal.

I have seen Scottish & Canadian lobster but they are not extreme level cannibals.

For your information, sometimes at grocery stores, you may see a pile of dead lobsters with their eyes retracted into their heads. This is often due to them killing each other in the tank.

Additionally, high temperatures can cause disease, making the habitat unsuitable for lobsters.

In 1998, in Long Island, Southern New England, all lobsters disappeared. The reasons were likely either high temperatures or disease, which drove them away.

2. Overfishing

Overfishing is another reason why lobsters eat each other. Overfishing has reduced the population of lobster predators, like cod, which has led to an increase in lobster offspring. As a result, lobsters encounter each other more frequently.

With large fish populations declining, lobster predation has also decreased. Smaller fish make it easier for lobsters to prey on them, as they are a favored food source.

3. Nutrition

When a lobster sheds its shell, it becomes a molted lobster. The new shell is soft and tender, and it needs calcium to harden it so it can protect itself from predators. To do this, they need nutrition, which they can get from their old shell by eating it.

Earlier, I mentioned that lobsters consume 2% of their body weight daily. They don’t just eat their old shells—eating other lobsters also provides them with nutritional benefits.

Let me share my experience. My aunt and uncle are skilled lobster and crab fishers from Nova Scotia. When I visit them, I often see them removing dead lobsters from the tank in the morning.

Interestingly, the live lobsters flip over the dead ones and eat their legs and antennae. Sometimes, if a lobster falls asleep, the others will eat its antennae.

We observed that the stronger lobsters push themselves into the corners to protect themselves, while the weaker ones stay in the middle, where others devour them from every angle.

To examine lobster cannibalism, Researchers studied young lobsters (Panulirus ornatus) using time-lapse photography over 30 days.

 The lobsters were kept in tanks with controlled conditions:

 18 liters of water per tank, a temperature of about 27.7°C, a pH of 8.10, and a salinity of 33.7 parts per thousand. 

Over 50 days, about 60% of the lobsters died. They observed 936 molts (when lobsters shed their old shells) and 229 deaths, meaning roughly 1 in 4 molts resulted in death. The time-lapse footage showed that 26 molts occurred, and 8 of these involved cannibalism (one lobster eating another).

This means that cannibalism happened in about 29% of molts. 

The study is the first to show that cannibalism is a common cause of death in these young lobsters, occurring in about 20-28% of the molts.

Is Lobster Cannibalism Common in the Wild or in Captivity?

Unfortunately, lobster cannibalism in captivity happens because lobstermen purposely don’t feed them at grocery stores. Why? If they feed them, the lobsters will defecate, dirtying the tank.

As a result, the lobsters often attack each other out of hunger.

Lobstermen band their claws with rubber strips, but I have seen hungry lobsters manage to open their claws and attack other lobsters, despite the rubber bands. In tanks or captivity, lobstermen don’t feed the lobsters. They only ship, hold, and sell them. If they were to feed the lobsters properly, their waste would dirty the water, putting the other lobsters at risk.

Therefore, lobster systems are kept in a frozen state to keep them inactive. During winter, their metabolic activities slow down, and lobsters can go weeks or months without eating.

What Do Lobsters Eat in the Wild?

 By nature, they are scavengers, feeding on mussels, crabs, small fish, clams, worms, and sea urchins. They are also nocturnal and avoid sunlight.

In Florida, at my research facility, I had freshwater lobsters for breeding experiments. I used to feed them fish pellets that sank to the bottom of the tank. I also fed them crabs, seals, rock gunnel, and flounder.

It’s important not to feed lobsters waste food, as this will ruin the water chemistry and lower oxygen levels. Any ammonia can be lethal. Always provide fresh food (consult with an aquarium specialist according to your area) and keep their tanks clean to ensure they thrive.

If they aren’t given a proper diet, they will inevitably resort to cannibalism in captivity.

Do Other Crustaceans Eat Each Other As Well?

Lobsters sometimes eat each other, but they’re not the only ones. If you think are crabs cannibals too? Then yes even some mammals can do this too.

Lobsters eat each other mainly to get nutrients like calcium, which helps their shells become strong. They might also eat each other because they’re fighting over food, protecting their space, or taking advantage of a weaker lobster.

Lobsters are extra vulnerable when they’re shedding their old shells. Some try to hide to avoid being eaten, but not all of them do this.

What Do Lobsters Eat In The Wild?

At the start of the article, I mentioned that the lobster diet was a mystery to us. We thought they were only scavengers. However, it’s interesting that we’ve now discovered what lobsters prefer to eat (I mentioned earlier how I fed them in my aquarium facility in Florida).

Lobsters eat what they find, as they are scavengers and consume decaying matter. However, they prefer fresh food (you should feed them according to their preferences), such as shrimp, crustaceans, worms, sea urchins, crabs, algae, mollusks, and carrion meat.

Let me precisely describe each one, which you can easily find to keep your lobsters healthy.

1. Lobsters love Crabs and other Crustaceans

Lobsters can prey on crabs and other crustaceans, including prawns, krill, barnacles, and crayfish. Clawed American lobsters have huge claws that can easily crush the hard shells of these animals.

2. Sea Urchins 

Lobsters love to eat sea urchins. Even though sea urchins have spines for protection, lobsters can easily flip them over to reach and eat the soft parts.

3. Fish

Lobsters can easily catch small fish when they swim by. When the timing is right, they use their claws to grab the fish skillfully.

4. Shrimps

Lobsters love to eat shrimps, which live at the bottom of the ocean and are especially common in the Caribbean. When lobsters are hungry, they eat shrimps eagerly.

5. Worms

Lobsters eat marine worms like flatworms, roundworms, horseshoe worms, and arrowworms. When these worms pass by, lobsters can easily grab and eat them.

6. Algae

Algae, full of nutrients, grow nearby, and lobsters eat both algae and small plants. Algae grow well on the sea beds, making it easy for lobsters to eat them.

6. Mollusks

Mollusks are a favorite food for lobsters. Different mollusks like slugs, snails, mussels, oysters, and octopuses are often slow, so lobsters use their strong claws to easily grab and eat them.

7. Carrion Meat

Don’t feed your lobsters dirty food, as I mentioned before. However, sometimes lobsters eat carrion meat (dead, decaying meat that floats in the ocean). Lobsters use their appendages to catch this food when it drifts by or is on the ocean floor.

How Cannibalism & Climate Change Affect Lobsters?

Lobsters, especially Homarus americanus, are having problems because of cannibalism and climate change. 

 Cannibalism & Its Effects

Lobsters sometimes eat each other (discussed above ) when there are too many of them or if they’re stressed.

 This can spread diseases among lobsters and make them sicker. It also causes more competition for food, which can make things worse.

Economic Issues

Robin Alden says there are so many lobsters right now that prices are very low. This makes it hard for fishermen to make money.

Climate Change Effects

 Lobsters are moving to cooler waters because the ocean is getting warmer. This means they are leaving their usual fishing spots.  The ocean is getting too warm for lobsters, which can make them sick and reduce their numbers.

What We Can Do?

 We need rules to limit how many lobsters are caught to help their numbers stay healthy. We should protect the places where lobsters live.  Fishermen and the lobster industry need to find new ways to work as lobster populations change.

Are Lobsters Immortal?

As a marine biologist, I’ve studied many types of lobsters at Whitney Lab in Florida.

One time, we had a lobster that was about 9 years old. We fed it meat every day because that’s what it liked. It got bigger over time, but we didn’t weigh it to avoid stressing it.

We could measure its carapace length to see how much it had grown. I worried that getting bigger might make it harder for the lobster to molt.

Lobsters have a special enzyme called “telomerase” that helps their cells divide and contributes to their long life. But they are not immortal. Lobsters can die from exhaustion. Their large size can make molting hard, which can eventually lead to their death.

Do Lobsters Feel Pain? The Ethical Debate

Whether lobsters feel pain is an important question when we talk about how to treat them, especially when they eat each other.

Personally, I  consider boiling lobsters alive is cruel and causes them a lot of pain. 

David Foster Wallace, in his essay “Consider the Lobster,” believes cooking them this way is wrong and that we should care about their suffering. 

But other scientists say lobsters might not feel pain like humans do, so they think it’s more like how we treat insects.

I love eating deep-fried soft-shell crabs and lobsters steamed with garlic butter. I also like cocktail shrimp, though I don’t have them as often.

This question also makes us think about how we treat all living things. Some people believe that no matter if lobsters feel pain or not, we should still treat them kindly and show respect.

Also Read:

1. Can Starfish Swim? 5 Must-Know Amazing Facts (Biologically Explained)
2. Life Cycle Of A Sand Dollar: 4 Fascinating Stages (Expert Ultimate Guide)
3. Decomposers Of The Ocean? 06 Important Types Scientifically Explained
4. Money Cowrie: The Amazing Journey And 5 Reasons It’s More Than Just Currency

FAQS

Conclusion

Lobster cannibalism isn’t typical, but warmer waters, overfishing, and limited food can trigger it. This affects both the environment and the economy, making it important to protect lobsters and their habitats.

References:

1. Bleakley, Bronwyn, ‘Cannibalism in Crustaceans’, in Martin Thiel, and Gary A. Wellborn (eds), Life Histories: Volume 5 (New York, 2018; online edn, Oxford Academic, 23 Sept. 2021),
2. Why Do Lobsters Eat Each Other?: And Other Odd Crustacean Adaptations Paperback – 30 July 2018
3. Growth and Mortality of Captive Caribbean Spiny Lobsters (Panulirus argus) in Florida, USA
4. Tropical rock lobster (Panulirus ornatus) uses chemoreception via the antennular lateral flagellum to identify conspecific ecdysis