Tiger sharks, voracious eaters, eat fish, seals, birds, and even old tires.
An appositive phrase is a noun phrase that describes or gives further information to another noun, and is placed right beside it. When the appositive phrase provides essential information about the noun (essential), it does not need to be framed by commas, however, when it is nonessential, it does need to be framed by commas.
In the sentence, Tiger sharks, voracious eaters, eat fish, seals, birds, and even old tires, voracious eaters is a nonessential appositive phrase as it gives further information about the noun Tiger sharks, and it can be removed from the sentence and the sentence would still make sense.
