Sonic Radar
"Ugh." Krune felt pangs of pain whenever the muscles surrounding him twitched, increasing the pressure applied on him. Every time this happened, he struggled to breathe, feeling a bit suffocated. Not to mention the fact that the walls of the muscles were layered over one another.
Since he was the one who slipped into it, Krune felt difficulty in breathing. After all, there wasn't enough air for him to breathe. At least, in the mouth chamber, there was enough oxygen for him to survive.
It seemed that the spherical creatures also required oxygen to operate. With that, the whale-like creature had evolved accordingly to circulate some of the air it inhaled into its mouth. That was why Krune was able to survive within it peacefully.