NEM 10V Lecture Notes - Lecture 35: Tunicate, Subphylum, Nematology
Nematology
Vertebrates:
Part 9 Vertebrates:
• The Chordates are a group that share four embryonic traits.
• These are traits that are present as the animal develops, but may not be present after birth.
• They have a notochord, that is a rod of stiff but flexible connective tissue, that extends
the length of the body and provides support.
• They have a dorsal, hollow nerve cord that parallels the notochord.
• They have gill slits.
• They have a muscular tail that extends beyond the anus.
• There are two types of Chordates: the Invertebrate Chordates, and the Vertebrate
Chordates.
• The invertebrate chordates include Tunicates and Lancelets (such as Amphioxus).
• Both groups live in the ocean and filter food from currents of water that pass through
their gill slits.
• Lancelets (subphylum Cephalochordata) are shaped like a fish and retain all characteristic
chordate traits as adults.
• Adult Tunicates (subphylum Urochordata) retain only the gill slits.
• Vertebrates (subphylum Vertebrata) are the third major chordate subgroup. Disks in the
vertebrate spine are vestiges of a notocord.
• All vertebrates have a distinct head with a brain.
• Their circulatory system is closed, with a single heart, there is a complete digestive tract,
and paired kidneys that filter blood.
• Vertebrate animals include the fish, amphibians, reptiles, birds and mammals.
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