What is the Size of a Crawfish?

The average size of a crawfish or crayfish is 7.5 cm (3 inches) long. However there are also crawfish that are 17.5 centimeters (6.9 in) in length. The crustacean is also known as a crawdad. It is related to the lobster.


There are over 500 species, nearly half of which are found in the United States. They are also found in the Tristan da Cunha Islands, New Zealand, and several East Asian and European countries. Majority of the species are found in freshwater. However there are also some that can live in salt water.

Physical Appearance

Whatever the size of a crawfish, the appearance is similar to other crustaceans like the shrimp. The crayfish’s thorax and head are joined together. The body is segmented and comes in different colors. Some are pink, while others are green, dark brown white or yellow.

The crayfish has four pairs of legs. The legs are not just used for walking. They are also used to probe fissures for food. The crustacean also has claw bearing chelipeds. These are used to collect food. It also serves as a weapon. There are also unique food legs and swimmerets beneath its abdomen. These will regenerate if broken.

Smallest and Largest

The biggest is the Astacopsis gouldi in Tasmania at 40 cm long and weighing 8 lbs (3.5 kg). The smallest is the Cambarellus diminutus found in the southeastern US. It is 2.5 cm long. The size of a crawfish used in aquariums belongs to the dwarf class like Cambarellus patzcuarensis.


The crayfish is often found in streams and lakes. They will often hide behind rocks. These crustaceans are shy, and this will be apparent even in crayfish kept in aquariums.

Many of them get active in the evenings. They like to eat different water plants, worms, insect larvae, algae and snails. The crayfish also feeds on dead fish worms, salmon eggs and corn.

Scientific studies show that mature crayfish feed heavily up until the day breaks. The younger ones show a preference to eating during the day. As the crayfish gets old, it starts to get more active during evenings. These crustaceans move slowly, but they can swim back where they came from if there is a threat.


The crayfish has an average lifespan of two years. Mating time usually takes place in November. The laying of eggs will happen the next spring. The eggs are kept below the female’s abdomen. The eggs will become more transparent as it matures.

The predators are the grackle (a bird), alligators, desman (an otter), burbots (a cod variant), painted turtles and the chicken turtle.

The crayfish is considered as food in many countries in the world. It is regarded as a delicacy in China, the United States, Mexico, France and Scandinavia.

While the sizes of crawfish vary, they all have a stiff exterior skeleton. When the crawfish gets too big for the skeleton, it will remove the skeleton and a new one will take its place. This is called molting.

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