Slice the avocados lengthwise, and remove the pit. Scoop out the flesh of the avocado, leaving about 1/2 inch on the peel. In a bowl, mix 1/2 c. crab meat, 1/2 c. cooked shrimp, 2 tbsp diced cucumber, diced cherry tomatoes, 1 tbsp mayonnaise, and 1 tsp chopped parsley. (Either add diced avocado to mix or slice and serve on the side) Season with salt, and pepper. Cover, and chill until serving. Spoon the seafood mixture into the hollowed centers of the avocado halves. Sprinkle the tops with paprika.