Cook pasta in boiling salted water according to directions.
While pasta is cooking place the tuna, the chiles and the capers in a large bowl. Top with the arugula (I place the arugula on top so that it has instant contact with the hot pasta.
Drain the pasta and add to the large bowl with the other ingredients, begin tossing to start wilting the arugula. Add the lemon juice, olive oil and salt and pepper to taste and toss to combine.
Notes
Canned tuna in water is fine, but if you can find it in olive oil it will have a richer flavor. Can substitute baby spinach for arugula. Olives can be substituted for capers.