Crawfish/Crawdad; Potāto/Potäto

Introducing, Bubba Gump, the crawfish.

I found this little guy while I was collecting bugs for my entomology lab collection this past spring. When I found him, he was about the size of one of his claws now, and he was mostly transparent. Now, he’s obviously a lot bigger. (I think he’s molted about 5 or 6 times now…the latest molt was a few days ago.)

Bubba waiting for something to fall in the water.

Bubba waiting for something to fall in the water.

Here’s a little video of him catching a (not-so-smart) minnow for dinner the other day. (I checked back later and there was zero evidence of any fish being there.)

 

Fun facts:

  • Crawfish are also called crayfish, crawdads, and even mud bugs.
  • They are in the group, “Astacidea”, which is made of decapod (“ten-footed”) crustaceans. (“deca”-ten, “poda”-foot)
  • If you keep crawfish in a tank with other fish, it will catch, kill, and eat them. There are exceptions for more aggressive fish, but I haven’t personally tested them, so don’t take my word on that. It will also eat most plants you put in there, but mine really hasn’t eaten the marimo moss balls I got; he just tears them up looking for food particles lodged in them.
  • Some crawfish have been found to carry the chytrid fungus that is killing frogs and other amphibians. You can read about it here. (I actually did a research project on this in high school.)
  • Crawfish eat their exuvia (shed exoskeleton), as it still contains nutrients. (Waste not, want not!)
  • Crawfish are in the group, Ecdysozoa, which includes all animals that shed their exoskeleton.
bubba molt

Here, you can see Bubba with his exuvia (to his right). Plural of exuvia is exuviae.

The process of molting is called “ecdysis”, and has several stages:

  1. Apolysis: the separation of the cuticle (outermost layer made of epicuticle and procuticle) from epidermis. (just underneath the procuticle)
  2. Secretion of inactive molting fluid by the epidermis. (Inactive, because it would digest epidermis if active)
  3. Cuticulin layer is formed to protect epidermis from molting fluid.
  4. Activation of molting fluid by ecdysteroids.
  5. Digestion & Absorption of old endocuticle. (inner-most layer of procuticle)
  6. Epidermis secretes a new procuticle.
  7. Ecdysis: the old exocuticle (part of procuticle) and epicuticle (part of epicuticle). If the animal cannot fully emerge from its old cuticle, it will die.
  8. Expansion of the new integument. (skin)
  9. Tanning/Sclerotization (hardening) of the new exocuticle. This step is triggered by neuropeptides and can take anywhere from hours to days to complete, and the animal is very vulnerable at this time.

{I don’t have a video of Bubba molting yet, but if/when I get one, you’ll get to see the process!}

arthropod integument

Arthropod integument. Clarification: Cuticle contains endo-, exo-, and epicuticle.
Not labeled: Procuticle, which contains the exocuticle and endocuticle.

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