-
Separate heads from shrimp. Put heads, carrots, coarsely chopped onion, parsley stems and 2 tablespoons oil in a 3-quart heavy saucepan, and cook, without adding any liquid, covered, over medium-low heat, stirring occasionally 15 minutes.
-
Meanwhile, shell shrimp, reserving shells, then halve shrimp lengthwise and devein.
-
Add shrimp shells, water, and 3/4 cup wine to pan (shrimp heads will turn liquid red), and bring to a simmer, skimming surface as necessary. Simmer stock gently, partially covered, 1 1/2 hours.
-
Strain stock through a medium-mesh sieve set over a bowl, pressing on and discarding solids.
-
Heat remaining 3 tablespoons oil in a 12-inch wide deep heavy skillet over medium-high heat until it shimmers. Add the mussels and remaining 3/4 cup wine, then cover and cook, shaking pan occasionally, until most of mussels are open, 2 to 3 minutes. Transfer mussels as opened with a slotted spoon to a colander set over a dish to collect juices and continue to cook until remaining mussels are open. (Discard any mussels unopened after 6 minutes.)
-
Add juices from dish to juices in skillet along with 1 cup shrimp stock an d salt to taste (remember that pasta will be well salted).
-
Meanwhile, cook linguine in a pasta pot of well-salted boiling water (it should taste almost like the sea) until barely al dente, about 8 minutes. Drain in a colander.
-
Add cherry tomatoes, calamari, chile (if using) and 2 tablespoons parsley to skillet and simmer over medium heat until tomatoes are softened, about 3 minutes.
-
Stir in linguine and simmer, uncovered, until linguine is al dente and has absorbed all the liquid, about 3 minutes, adding some more shrimp broth if pasta absorbs all of liquid before it is al dente.
-
Stir in mussels and shrimp and cook, stirring gently, until shrimp turn pink, about 1 minute.
-
Sprinkle with remaining 2 tablespoons parsley and serve immediately.
-
Pass olive oil to drizzle over individual plates of pasta.