Before I comment on your story, let me get some mechanical details out of the way. You write in a musical, almost poetic style that is appropriate for a children's book, but you need to let someone who knows what they're doing proof your manuscript. There are a few too many places that cease to fall under the "literary license" category and instead come out sounding just wrong.

Here's one that sounds like it may have just gotten mangled in a revision gone bad. The first sentence is fine, the second is not really a sentence but it still works stylistically. The last phrase is too odd to leave there.

"The fish, the coral, and even the oysters, all are bigger than me. More important than me." continued the shrimp-like little fellow his lamentations.

Here's a case of bad grammar.

His family, eaten by a whale, and he had done nothing. Couldn't do nothing!

You could say Couldn't do anything, but it's always stronger to wrap a negative in a positive statement: Could do nothing.

Bloopers like this stand out all the more sharply since there are so few of them. But even one is enough to make your readers wonder if you know what you're doing, which is a shame since, clearly, you do know what you're doing.

Now, to the story. At first glance it feels a little dark for a child audience. I mean, let's face it, the natural world is a brutal place and you prove it. Creatures die so others can live. Still, it's a lesson that must be learned, and you seem to have found a way to present it gently, without sugar-coating it overly much. In a children's literary universe that has room for "Everybody Farts," and "Everybody Poops," there certainly should be room for a tale like this.

You should look for an illustrator. The content is begging for an inspired visual touch. And children's books would seem to require it. I think you have a hot property here; polish it up, add illustrations and look for a publisher.