1 pound shrimp (24 to 30 per lb.), peeled and deveined
Salt and pepper
How to Make It
Trim off and discard tough stems and base of fennel head. Rinse fennel, core, and chop.
In a 6- to 8-quart pan over medium-high heat, stir fennel, oil, onion, garlic, and 2 tablespoons parsley until onion is limp, 8 to 10 minutes.
Add diced tomatoes (including juice), white wine, tomato paste, basil, oregano, and chile flakes. Bring to a boil over high heat. Cover and simmer on low heat until flavors are well blended, about 15 minutes.
Add clams and crab. Cover and bring to a boil over high heat, then reduce heat and simmer, covered, for 5 minutes. Stir in shrimp, cover and simmer, until clams pop open, shrimp turn pink, and crab is hot, 6 to 9 minutes longer; remove seafood as it finishes cooking. Discard clams that do not open. Add salt and pepper to taste. Ladle broth and seafood into wide bowls. Sprinkle with remaining parsley.