<p>Shafts of sunlight angle into glistening turquoise water. Four beluga whales, in near-synchronized perfection, glide by, eyeing the cluster of visitors on the other side of a huge picture window.</p><p>One of those visitors is Karisa Tang, Shedd Aquarium’s vice president of animal health. Tang’s hand goes to her chest at the approach of these most graceful creatures — even though she’s seen Acadia, Lillooet, Osiris, and Sierra countless times before.</p><p>“That’s stunning in the sunlight,” Tang says during a visit by the Sun-Times to the aquarium Thursday morning in an area — for the time being — closed to the public.</p><p>Two more Shedd scientists huddle nearby, eyes glued to computer screens as they monitor the health of the new arrivals.</p><p>So far, says Tang, the signs look good for the whales, which arrived just before dawn Tuesday from the now-shuttered Marineland, a once-popular tourist attraction in Niagara Falls, Ontario.</p><p>“We are seeing them foraging, engaging with the habitat, being curious, exploring together.