Is there any species of whale that can swallow a human whole?
The Baleen whales, as you state cannot open their mouths beyond a certain width (this is because they feed by a form of filtration). The Toothed whales, on the other hand, can open their mouth fully. The largest Toothed whale is the Sperm Whale (Physeter macrocephalus) at an average length of 11-16m with a jaw equal to around 25% of it’s length. It’s possible therefore that a human being could be swallowed whole by a Sperm whale. It’s unlikely that any of the other toothed whales (the Orca or the Beaked whales, etc.) would be large enough to swallow an adult human. Remember, of course, that it is extremely unlikely that a human WOULD get swallowed by a Sperm whale, due to the fact they are distributed around 1000m below the water, can spend long times submerged and travel long distances at great depth. There is not even that much footage of the Sperm whale – let alone the opportunity for someone to get swallowed by one!
