The largest thing a blue whale could potentially take into its mouth would be something about the size of a small car, but it wouldn't be able to swallow it.
Here's why:
* Baleen: Their baleen plates act like a giant sieve, trapping small organisms while letting the water flow out. They cannot swallow large objects.
* Throat: Their throats are surprisingly narrow, only about the size of a grapefruit. This is designed for filtering small creatures, not large objects.
So, while a blue whale might accidentally take a large object into its mouth, it wouldn't be able to swallow it and would likely spit it out.