A salmon goes through seven distinct stages in its life cycle. In the second stage, pictured here, it's called an alevin. After hatching from its egg, the still-developing alevin retains the yolk sac, which serves as a nutrient source as the protofish continues to grow eyes, teeth, and digestive and respiratory systems. In the wild, alevins stay buried in a gravel nest in their birth stream. Photographer Amy Gulick captured this unique stage of a salmon's life at a hatchery.