Crayfish are crustaceans minimally mentioned in the How to Train Your Dragon Book series.
Crayfish - also called Crawfish, Crawdads, or a few other names - are small decapod crustaceans that outwardly appear similar in form to Lobsters. While Lobsters and Crayfish occur in the Infraorder Astacidea, they have different groupings within Astacidea. Crayfish belong to the Superfamily Astacoidea and Parastacoidea.
Crayfish use their many legs for walking, have a flatish muscular tail, long antennae, and two large claws to grab things with. They eat a variety of foods, including plant material and animal material, both dead and alive. They require a freshwater environment. The type of water habitat varies by species - some prefer running water, while other prefer muddy, slow moving water or swamps.
In real life, crayfish are predominantly used as food, mostly in America, Asia and Australia. They area prepared like lobster, that is, typically boiled. Crayfish can also be used a bait for some species of fish, and are occasionally kept as pets in freshwater aquariums.
In the Books, crayfish are mentioned only as a descriptor.
|“||This is the work of Hiccup Horrendous Haddock the Third or I am a freshwater crayfish - which I'm not of course.||”|
|— Thin Prefect|