The immitation crab is ready to eat but not the tuna unless it specified as "sushi grade tuna" or "shashimi grade tuna".
It may not kill you but it probably won't taste very good (and it could kill you if the right bacteria is on it). There are some other specifics (I will post a link if you want the details) but for the average consumer it just means really fresh, precautions taken so no bacteria is on it.
Even when I buy sushi-grade, I rinse it in lemon juice (quickly so it doesn't chemically cook it) to kill any bacteria. The reason being even though it is sushi-grade, the best stuff is usually reserved for restaurants so I feel more comfortable taking that precaution.