Crayfish: All You Need to Know for a Fascinating Deep Dive

Crayfish are fascinating aquatic invertebrates that can be found in various freshwater habitats, such as lakes, streams, and rivers. They play a crucial role in their ecosystems, serving as a food source for a wide range of animal species, including bass and catfish. In addition to their ecological importance, crayfish are also commonly used in cuisine, particularly in Cajun dishes.

There are over 600 species of crayfish worldwide, with a diverse range of physical characteristics. Some common traits across species include elongated and segmented bodies, strong pincers, and distinct walking legs. Their body lengths can vary, with certain species like the Big Sandy crayfish measuring between 3.0 to 4.0 inches.

In this article, we will explore various aspects of crayfish, such as their biology, behavior, distribution, and significance in human culture. We will also delve into the diverse species of crayfish and discuss their unique features and adaptations. So, get ready to embark on a captivating journey into the world of these remarkable aquatic creatures.

Crayfish Basics

Crayfish Species

Crayfish, also known as crawfish or freshwater crustaceans, are related to lobsters and crabs. There are many different species of crayfish; some noteworthy examples include:

  • Dwarf Crayfish (Cambarellus patzcuarensis)
  • Blue Crayfish (Procambarus alleni)
  • Cherax destructor
  • Cherax quadricarinatus

Some crayfish, like the Signal crayfish, are native to specific regions, while others have been introduced.

Examples of crayfish features:

  • Exoskeleton
  • Two large pincers
  • Multiple legs
  • Unique color patterns

Characteristics of crayfish include:

  • Primarily nocturnal
  • Omnivorous, feeding on algae and small aquatic animals
  • Play a vital role in the aquatic ecosystem

Crayfish commonly mate in spring or fall, and females carry fertilized eggs under their tails before they hatch into tiny crayfish.

Freshwater vs Saltwater Crayfish

Most crayfish are freshwater species, living in lakes, rivers, and streams. However, a few species can be found in saltwater environments.

Here’s a comparison table of freshwater and saltwater crayfish:

Freshwater Crayfish Saltwater Crayfish
Habitat Lakes, rivers, and streams Saltwater environments, estuaries
Size Varying sizes, typically smaller than saltwater species Generally larger
Examples Dwarf crayfish, blue crayfish, electric blue crayfish Tropical spiny lobster

An essential difference is the diversity of species found in freshwater habitats compared to those in saltwater environments. Moreover, freshwater crayfish are popular as pets and in the aquarium trade due to their unique appearance and behavior.

Crayfish Life Cycle

Molting and Growth

Crayfish grow through a process called molting, where they shed their old exoskeleton and produce a new, larger one. This process allows crayfish to continuously grow throughout their lives. Some factors influencing their growth include:

  • Habitat: Crayfish thrive in various environments, such as streams, ponds, and lakes, with substrates like gravel, rocks, or mud that allow them to hide and find food.
  • Nutrition: They are omnivorous, consuming plants, snails, fishes, and even other crayfish.

Molting can be risky for crayfish as they are vulnerable to predators and injuries during this time. After molting, it takes time for the new exoskeleton to harden, during which crayfish seek safe hiding spots.

Breeding and Reproduction

Crayfish mating usually occurs in the late summer or early autumn. Males can be more aggressive during this time, seeking out females for mating. After mating, the female crayfish will lay fertilized eggs, which she attaches to her swimmerets for incubation. Here are some critical points about crayfish reproduction:

  • Eggs: Females carry eggs under their tails for several weeks until they hatch.
  • Crayfish care: The female takes care of the eggs by fanning them with her swimmerets to oxygenate and clean them.
  • Habitat: Depending on the species, crayfish may burrow into the substrate to lay and incubate their eggs.
  • Lifespan: Crayfish have an average lifespan of 2-3 years, although some species may live longer.

https://mdc.mo.gov/wildlife/wildlife-facts/aquatic-invertebrate-facts/crayfish-facts

When setting up an aquarium for crayfish, it is crucial to consider their natural habitat and water parameters. For the substrate, use materials like sand, gravel, or stones to provide hiding spaces. Provide adequate filtration and maintain water quality, ensuring proper water parameters such as temperature, pH, and hardness. Include live plants, which can act as food sources and hiding spots. Since crayfish can be aggressive towards other aquatic creatures, it is advisable to take this into account when setting up a community aquarium.

Crayfish in Aquariums

Creating a Suitable Habitat

To set up a crayfish habitat, consider:

  • Aquarium size: Opt for a minimum of 20 gallons.
  • Equipment: Install a filter, heater, and air pump.
  • Substrate: Use muted-colored gravel or sand.
  • Hideouts: Crayfish need hiding spots, like PVC pipes or clay pots.
  • Plants: Incorporate live plants, but note that crayfish may uproot them.
  • Water balance: Maintain a pH of 7.0-8.0 and temperature of 65-75°F.

Choosing Tank Mates

Crayfish can coexist with these tank mates:

  • Orb Snail, Ramshorn Snail, Trumpet Snail, Mystery Snail, and Pond Snail.
  • Guppies, though crayfish may prey on them occasionally.

Avoid aggressive fish or those with long fins, as crayfish can attack and damage them.

Tank Mate Works with Crayfish Note
Snails Yes Provide a natural environment
Guppies Yes Crayfish may prey on them
Aggressive fish No Can damage each other

Aquarium Maintenance

Keep your crayfish’s environment healthy by:

  • Water level: Always keep it consistent.
  • Water clean: Perform 25% water changes weekly.
  • Use water conditioner: Remove harmful contaminants.
  • Monitor water balance: Test pH, ammonia, nitrite, and nitrate regularly.
  • Harvest: Remove uneaten food and waste to maintain a balanced ecosystem.

Crayfish Diet and Feeding

Types of Food

Crayfish are freshwater crustaceans with a diverse diet. They consume:

  • Plants: such as algae and aquatic vegetation
  • Small animals: including snails and fish
  • Detritus: decomposing organic matter found in their habitat1

Feeding Techniques

Crayfish have specific techniques to catch and consume their food:

  • Predation: actively hunting and catching prey using their claws
  • Scavenging: searching for dead or decaying matter
  • Grazing: feeding on algae and plants using their mouthparts2

Schedules

A crayfish’s feeding schedule can vary depending on its size, environment, and availability of food. In general, crayfish follow these feeding patterns:

  • Small crayfish: frequent feeding throughout the day and night
  • Adult crayfish: can tolerate longer intervals between meals, usually at dawn and dusk. 3

Pro: Adaptable eating habits allow crayfish to survive in different habitats
Con: Excessive feeding can lead to environmental imbalances

Comparison Table

Feature Example Benefit
Food type algae, detritus Balanced diet
Feeding predation, scavenging Less competition
Schedule dawn and dusk feeding4 Energy conservation

Footnotes

  1. MSU Extension

  2. Washington Department of Fish & Wildlife

  3. Fisheries2

  4. NPS Invasive Rusty Crayfish

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.

Letter 1 – Crayfish

 

Bug with claws and many legs
Location: Tarpon Springs, FL
April 1, 2011 12:49 am
Hello,
I live in Tarpon Springs and we just had a huge rain storm today. Well, when I left the house to go to the store, I found this huge crab like bug sitting on the driveway. It was maybe about 3 inches long, had claws and I noticed many legs when I flipped it over with my foot. Can you please identify this curious looking creature?
Signature: Joey Tooze

Crayfish

Hi Joey,
This freshwater crustacean is commonly called a Crayfish, though it has many other common names, some quite localized in their use, including Crawfish, Crawdad and Clawfish.  We are amused at the name you used to title your photographs and we think that Clawbug is probably a name that is used by some people when talking about the Crayfish.

Thank you!!!  Btw, Awesome site! 🙂

Letter 2 – Crayfish

 

Unidentified bug
Location:  Eastern Shore, Virginia. [chincoteague]
July 27, 2010 7:33 am
Hello! my grandmother found this bug i her driveway already dead and hallow? [i think] we have no idea what it is and we have a confused 6 year old! please help!
Jessica and Collin

Crayfish

Dear Jessica and Collin,
This is a Crayfish, a freshwater crustacean.  Does your grandmother live near a body of water?  Your letter is quite timely because we just posted an identification of what we believe to be a Crayfish fishing lure made of rubber.

Letter 3 – Crayfish

 

bug with a crab-like claw?
Location:  Amherst, NY near Buffalo
August 13, 2010 7:03 pm
Hi –
I encountered this interesting looking creature while walking my dog on the lawn of my condo complex in Suburban Buffalo, NY in mid-August. It’s about 3 inches long and appears to have a crab-like claw on the right side.
Never saw anything quite that big around here!
Many thanks!
Sheri

Crayfish

Hi Sheri,
This Crayfish is a freshwater crustacean but they can survive out of the water.  Crayfish are also called Clawfish, Crawfish and Crawdads.

Thank you, Daniel!  I thought it looked a bit like a small lobster or possibly a crayfish, but we’re not that close to a fresh water source (perhaps a mile or so from the nearest creek).
Really appreciate your assistance.
Best,
Sheri

Hi Again Sheri,
Crayfish are able to survive out of the water.  It is possible that this Crayfish was captured and accidentally dropped by a bird or other predator, or even left by a human.  It is also possible that the area where it was found is low lying land that floods when it rains.  Crayfish will dig into the mud and produce a type of chimney around the burrow.  When we were young, we often encountered Crayfish chimneys in fields far from a source of water.

Letter 4 – Crayfish

 

What is this?
Location: By my fence in the backyard.
February 27, 2011 10:44 am
I found this wondering in my yard. It has a stinger on the back but its down right now as I was hovering over it. It tried to strike my dogs a couple of times..
Signature: any way

Crayfish

Dear any way,
Crayfish, Crawfish, Clawfish and Crawdad are just a few of the common names attributed to this freshwater crustacean that burrows into the mud during times of drought.

Update:  June 23, 2016
Though they are not insects, Crayfish are surely edible, and because we recently directed a commenter to our Edible Insects page and because we just posted a recent Crayfish image, we decided we needed to add a tasty looking Crayfish to the tag.

Letter 5 – Crayfish

 

Subject: Crawfish Hanging Out In the Street
Location: Northeastern US (Western MA)
May 24, 2013 8:08 pm
I found this bug in the road and have no idea what it is. If anyone has any idea what type of bug it is my thirst for knowledge would be satisfied as far as bugs I have found in the road goes. It was probably about 3-5 inches in length. Thanks everyone for any help.
Signature: The Bug Discoverer

Crawfish
Crawfish

Hi Bug Discoverer,
Crawfish, Crayfish and Crawdad are all commonly used names for this small crustacean.

Letter 6 – Crayfish

 

Subject: Southwest Florida driveway find
Location: Southwest Florida
August 26, 2014 4:54 pm
Found this on a driveway that is about 100 feet from a pond…it has a friend a little freaked out. Can you help? Saw some other post about a claw on the right side only, and I think this one fits that bill too. Appreciate an accurate assessment. Thanks!
Signature: Scott

Crayfish
Crayfish

Dear Scott,
this is a positively gorgeous image of a Crayfish.  Crayfish are called Crawdads in Louisiana where they are eaten.

Authors

    by
  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. whatsthatbug.com is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

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  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

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