Downtown Campus Biology > Biology 182 > Lesson 10 Activities > Step 3
In Class Activity - Animals of the Biology Learning Center |
Time: This activity will take 20 - 40 min. to complete.
Kit # 271, living animals in Biology Learning Center
Introduction
The phylum Chordata is diverse - it includes all vertebrates, from fishes to humans. The phylum also includes several other animals that don't have vertebrae, such as tunicates and lancelets.
All animals in the phylum Chordata have the following characteristics:
- a nerve cord
- a notochord
- pharyngeal slits
- a postanal tail
 Fig. 48.2 from text |
In vertebrates, the nerve cord develops into the brain and spinal cord before birth. The notochord is a flexible rod right below the nerve cord. In most vertebrates, the notochord becomes the vertebral column that surrounds the spinal cord. The pharyngeal pouches develop into gills, and disappear before birth in animals without gills. The postanal tail develops into a tail, or disappears before birth, as in the case of humans. |
In lesson 1, we examined the similarities between vertebrate embryos, indicating that these fishes, reptiles, birds, and humans all share a common ancestor.
 Fig. 21.16 from text |
The Tunicate Tale Tunicates (sea squirts) may not look like belong in the same phylum as vertebrates like horses and humans, but they do.
In tunicates, the larvae have a nerve cord, notochord, pharyngeal slits and a postanal tail. The adult loses these structures and becomes a stationary filter feeder. |
Get kit #271. Here you'll see some preserved samples of tunicates and lancelets, as well as some vertebrates.
Be able to answer the following question:
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Why is a tunicate classified in the phylum Chordata?