Crayfish vs Lobster: 5 Key Differences Explained

Written by Hannah Ward
Published: November 12, 2021
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Crayfish and lobsters and often confused for one another, and it certainly doesn’t help when in some regions lobsters are called crayfish.  It’s an easy mistake to make – after all, they do look incredibly similar.  Both live in water, have hard exoskeletons and large pincers.  But the truth is they are actually two completely different species.

But just how alike are they really?  For a start, there’s a vast difference in size and they eat different things.  However, possibly the most important difference is that they live in completely different places – one lives in the sea while the other lives in rivers and lakes.  Join us to discover all of their differences and find out exactly which one lives where.

Comparing Lobster vs Crayfish

Lobsters and crayfish are both crustaceans and invertebrates who shed their tough exoskeleton many times over the course of their lives.  They’re also both decapods and have ten legs.  So, if they’ve got so many things in common then you’re probably wondering if they are even any differences between them at all.  Well, despite their similarities there are still some key differences, and some even make it easy to distinguish between the two.

Check out the chart below to learn a few of the main differences.

LobsterCrayfish
SizeUsually 8 to 20 inches long2 – 6 inches long
HabitatSaltwater – in all oceans on sandy and muddy bottomsFreshwater – lakes, rivers, streams, ponds. Usually under rocks and in crevices at the bottom
ColorUsually greenish blue or greenish brown, but can be widely variedUsually dark blue, dark green, or black
DietSmall fish, snails, clams, mollusks, other small crustaceansInsects, worms, plants
LifespanUp to 100 yearsBetween 1 and 20 years
Number of speciesAround 30 true (clawed) lobstersMore than 640

The 5 Key Differences Between Crayfish and Lobster

Animals With Exoskeletons-Crayfish
Despite their similiar appearance, crayfish and lobsters are completely different animals

Sergey Lavrentev/Shutterstock.com

Crayfish vs Lobster: Size

One of the differences between crayfish and lobsters is their size.  Crayfish are much smaller than lobsters and range between 2 and 6 inches long.  Lobsters are much larger and are typically between 8 and 20 inches long, but some can even be up to several feet in length.

Crayfish vs Lobster: Habitat

The easiest way to tell the difference between lobsters and crayfish is to look at where are living.  Crayfish live in freshwater rivers, lakes, ponds, and streams while lobsters live in saltwater in seas and oceans.  However, both are bottom dwellers and like to lurk under rocks and in crevices on the muddy bottoms.

Crayfish vs Lobster: Color

At first glance there isn’t much difference between the color of lobsters and crayfish – crayfish are dark blue, green, or black, while lobsters are greenish blue or greenish brown.  However, lobsters can sometimes be seen in a wide variety of bright colors, including albino, red, orange, or blue.

Crayfish vs Lobster: Diet

Crayfish and lobsters also have different diets, although they are both omnivores.  Lobsters eat mainly small fish, mollusks, snails, clams, some plants, and other small crustaceans.  Crayfish eat a mixture of plants, worms, insects, and dead plants and animals.

Animals With Exoskeletons-European Lobster
Lobsters are far bigger than crayfish and can live for up to 100 years

davemhuntphotography/Shutterstock.com

Crayfish vs Lobster: Lifespan

Lobsters and crayfish also have vastly different lifespans.  Depending on the species, crayfish live for between 1 and 20 years.  However, lobsters usually live for anything up to 100 years.  Incredibly, some even far exceed that and the oldest lobster ever caught was estimated to be 140 years old.  The secret to their longevity is believed to be due to telomerase – an enzyme that repairs DNA.

FAQ’s (Frequently Asked Questions)

Are lobsters and crayfish from the same family group?

No, lobsters are from the family group Nephropidae while crayfish are from four family groups – Astacidae, Cambaridae, Cambaroididae, and Parastacidae.

Are false lobsters really lobsters or not?

No, although they share a name, reef, spiny, slipper, and squat lobsters are not true lobsters.  Only clawed lobsters are classed as true lobsters.  Reef, spiny, slipper, and squat lobsters are from different family groups to true lobsters and there are a number of differences between them, although the main difference is in their claws.

Can lobsters survive in freshwater?

No, lobsters need salt to survive and maintain the salinity of their bodies.  If they are in freshwater for any prolonged period of time they will die.

Can crayfish survive in saltwater?

No, although some species of crayfish are found in brackish water, they cannot survive entirely in saltwater.

What are the predators of crayfish?

The natural predators of crayfish are large fish, otters, raccoons, mink, and some large birds.  Predators of their eggs and young are fish and other crayfish.

What are the predators of lobsters?

The natural predators of lobsters are varied as lobsters are found in so many different oceans, but some of them include large fish, eels, crabs, and seals.

Why was it once thought that lobsters can live forever?

Many people originally thought that lobsters were immortal because of a few things.  The first is the presence of telomerase which is an enzyme that can repair DNA and cells that are lost or damaged each time they shed their exoskeleton.  The second reason is because lobsters never stop growing and as adults they shed their entire exoskeleton every two to three years.  Also, even as they age, lobsters continue to reproduce and don’t become infertile.  However, lobsters do die eventually, and those at great ages die during a moult (when they are shedding their exoskeleton).  This happens because it is too exhausting for them to shed such a large shell and they get stuck part way through and die.

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About the Author

I'm an avid animal lover, and when not writing I can be found on my farm surrounded by dogs, horses, and sheep.

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