Survey Season at Cypress Bend
1Cypress Bend Wildlife Refuge protects marshes and woods along the Gulf of Mexico coast. Every spring and summer, refuge staff run animal surveys. They count alligator nests along the canals, mark river cooter turtles that crawl up the banks to lay eggs, count great egrets in their nesting colony, and record green anole lizards and nine-banded armadillos along the trails. This year, eighth grader Cyrus Adeyemi joined the surveys as a summer volunteer with the refuge biologist, Dr. Wynona Bellamy.
2On rainy days, Dr. Bellamy showed Cyrus photos and models of embryos of the same five kinds of animals from a university collection. No refuge nests were opened for the study. For the first part of development, the five embryos look much alike: each has a curled body, four small limb buds and a tail. Differences show up as the bones begin to form.
3The turtle surprised Cyrus most. An adult turtle's upper shell looks like nothing on any other reptile. In the embryo, though, the shell grows from parts that every reptile has. The turtle's ribs do not curve down around the body as they do in the alligator and the lizard. Instead, they grow straight out sideways under the skin of the back, then widen and join with the backbone to form the shell. The armadillo also has a hard shell as an adult, but its embryo's ribs curve down like a lizard's. Its shell forms later, from small bony plates that grow in the skin.
4The egret embryo has its own surprises. An adult egret's wing ends in a few small finger bones that are partly joined into one stiff piece, and its short tail ends in a knob of joined bones that holds the tail feathers. In the embryo, the wing starts with three separate fingers, and the tail is long, with many separate bones. As the embryo grows, the finger bones partly join and the tail shortens, and its last bones join together.
5Dr. Bellamy reminded Cyrus that biologists compare early stages because animals that share a pattern of development often share a common ancestor, even when the adults look very different.