…and other nonaquatic vertebrates exhibit gill slits even though they never breathe through gills. These slits are found in the embryos of all vertebrates because they share as common ancestors the fish in which these structures first evolved. Human embryos also exhibit by the fourth week of development a well-defined….
The idea that human fetuses have gill slits is a part of what was known as the Biogenetic Law. “The idea that the embryo of a complex animal goes through stages resembling the embryos of its ancestors is called the Biogenetic Law.”
Cephalochordates usually live partially buried in marine sand and gravel. …and other nonaquatic vertebrates exhibit gill slits even though they never breathe through gills. These slits are found in the embryos of all vertebrates because they share as common ancestors the fish in which these structures first evolved.
Human Gill Slits Wide Image
