well of course beluga has a skull!! that's just not where it is.
see, you wouldn't necessarily pick up on this, but beluga skulls (and most cetacean skulls in general) are pretty much
so what's going on up there? well, most of the beluga's head is taken up by soft tissue and a large organ called the melon, which is basically a big ol waterballoon of semiliquid fat!
(boob. it's a head boob.)
this organ is found in every toothed whale and dolphin species on the planet and it's INCREDIBLY important, because the melon is what lets them echolocate!
the actual sound-producing organ is inside their nasal passage of all places, which sits up behind there, but the melon is what's actually used to fine-tune the soundwaves into the laser-accurate pinpoints that dolphins and toothed whales are so famous for.
tldr: without their head boob, belugas and their relatives would be literally flying blind!