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Biology LibreTexts

Chordates

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Read Chordates in the lecture notes.

Subphylum Urochordata (Tunicates)

Subphylum Cephalochordata (Lancelets)

Examine a slide of a lancelet using a dissecting microscope.

Although this animal is not a vertebrate, it has all three of the chordate characteristics. Identify the notochord, nerve chord, and pharyngeal gill slits.

Notice the segmented pattern of the muscles, also a chordate characteristic.

When feeding, water enters the mouth and moves into the pharynx, a chamber posterior to the mouth. The gill slits are openings in the wall of the pharynx and function to allow water to pass out of the pharynx while filtering particles out of the water. The particles move into the gut for digestion. After passing through the gill slits, water exits via the atriopore.

Examine a preserved lancelet and observe the segmented pattern of muscles and the atriopore located on the ventral surface posterior to the pharynx.

Subphylum Vertebrata (Vertebrates)

Read Vertebrates (Subphylum Vertebrata) in the lecture notes.

Read the section in the lecture notes that corresponds to each of the groups of vertebrates that are displayed.