In a large bowl, stir together the shredded zucchini, crab (if using), eggs, bread crumbs, onion, & Old Bay seasoning. Form into patties – at least as big as a golf ball & no bigger than a baseball. I usually go the baseball route. Dredge the crab cakes in the flour, & arrange in a skillet of hot oil, on medium-high heat. Fry patties in hot oil on each side until nicely browned. Remove to a paper towel lined plate, & sprinkle with salt and pepper while still hot.