Your curiosity gets the better of you as you walk through the shark door. Inside you find a large pool with several fish inside but no shark. You suddenly feel an irresistible longing to jump in. You strip down and dive right in.
After swimming around for a few minutes you realize something is wrong. Your skin is tingling and looks whiter than usual. You begin to realize something horribly bad is happening when you notice that all the hair on your body has vanished. You then see your legs. They’ve taken on a bluish gray hue and the skin is unnaturally rough, like sandpaper. You have no idea what’s going on for a moment but then it hits you: you’re turning into a shark! And almost to confirm this new revelation that your legs and feet have begun to bind themselves.
They melt together into a pillar of powerful muscles. Your denticle-covered epidermis continues to flow down towards your feet as they initiate the process of forming your tail fin. You examine your transforming feet, watching as they join at the heel. They swivel diagonally with a sharp *crack*. The grow longer, wider, and stronger, becoming your strong tail fluke. The last remnants of your toes disappear while you feel your bones soften into a rubbery yet sturdy material.
Your changes showed no sign of slowing down. You’ve since given up trying to leave, since you were already basically a merperson now. That, and your arms are losing their strength and shrinking. Your hands are utterly useless globs of skin and dissolving bones at the moment. There is no way you’re getting out of this one.
Your upper torso and neck swells as gills form from where your ribcage used to be. The globby mass that were your arms soon smoothed over into your far more streamlined pectoral fins. A giant triangular dorsal fin erupted from your back. Just below where your shoulder blades used to be.
The blue skin covers your head, and your face has begun to push itself forward. Your nose flattens against your expanding snout, leaving only your nasal openings. You felt like sneezing as the insides grew more sensitive, to the point where you could detect blood in the water from miles away. Just under your snout, you feel an odd, electrical buzzing. That must be your electrosensory organs kicking in.
Your teeth are forced out of their places as your jaw widens. They grow larger, sharper, stronger, until your teeth has become serrated blades. There’s pain in your maw as more teeth start to pierce your gums, all ready to replace whatever tooth falls out.
Your eyes grow, the pupils becoming able to fluctuate from catlike slits to obsidian voids. Your eyelids are replaced with a thin membrane.
The water around you thrums with electricity, and your nose fills with the scent of nearby life.
Suddenly those fish look quite appetizing.