Library

Station #1: Comparative Embryology

By Lindsey Turner
Last updated almost 4 years ago
6 Questions
Embryology is a branch of comparative anatomy which studies the development of vertebrate animals (animals with backbones) before birth or hatching. Embryos are offspring in the process of development, before all vital structures have developed. Like adults, embryos show similarities which can support common ancestry. For example, all vertebrate embryos have gill slits and tails, as shown in pictures below. The “gill slits” are not gills, however. They connect the throat to the outside early in development but eventually close in many species; only in fish and larval amphibians do they contribute to the development of gills. In mammals, the tissue between the first gill slits forms part of the lower jaw and the bones of the inner ear. The embryonic tail does not develop into a tail in all species; in humans, it is reduced during development to the coccyx, or tailbone. Similar structures during development support common ancestry.
1.

What is an embryo?

2.

What is a vertebrate?

3.

Is it easier to distinguish which embryo represents each animal in the earliest stage of development or in the latest stage of development? Explain.

4.

Look at the earliest stage of embryo development at the top of the first picture. List three characteristics that all of these vertebrate embryos share in common (Hint: they’re labeled in the picture!)

5.

Look at the latest stage of embryo development at the bottom of the first picture. Determine which embryo is a fish, turtle, salamander, chicken, and rabbit.

6.

Big Question: How is the comparison of embryos used to determine the relationship between species?