The red swamp crayfish, from the Mississippi delta in Louisiana, is the largest native species. White river crayfish, from northern Louisiana, and Pacific crayfish from California and Oregon, are slightly smaller but have a similar taste. Soft-shell crayfish, taken during the molt, can be eaten shell and all, but don’t eat the two hard stones (gastroliths) hidden in the head. Wild or farm-raised crayfish are available live or frozen whole, or you can buy frozen shelled crayfish tail. Soft-shell crayfish are sometimes available.