Exciting Whale Shark Facts for Kids The whale shark is the biggest fish that can be found in the deep, blue ocean. They have huge, gaping mouths that can suck in tons of food in just one gulp. They can also live for long periods of time. Although this species of fish has been here for millions of years, very little information is still known about them. And despite their large appearance, observing them for a long time is a very difficult task.