BIOE 214 Biology of Vertebrates: Chordates and Phylum Chordata Quiz

Characteristics of Chordates

• A defining characteristic of chordates is the presence of a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail at some stage in their lives.

Phylum and Subphylum

• The phylum that includes vertebrates is Chordata.
• The subphylum that includes tunicates and sea-squirts is Urochordata.

Embryonic Development

• The notochord is the first part of the endoskeleton to appear during embryonic development in chordates.

Vertebrate Characteristics

• In most vertebrates, the vertebrae act as an axis for muscle attachment.

Invertebrate Characteristics

• In most invertebrate phyla, the nerve cord is located ventrally.

Pharyngeal Slits

• The function of pharyngeal slits in lower vertebrates is to allow for the passage of water, which helps in filter feeding.
• The endostyle secretes mucus to trap small food particles coming in from the mouth.
• In most vertebrates, the endostyle develops into the thyroid gland.

Urochordata Characteristics

• The function of the post-anal tail in larvae during their free-swimming stages is to aid in movement.

Ascidians

• The common name for the Urochordata class Ascidiacea is sea-squirts or tunicates.
• The most diverse and common class within the subphylum Urochordata is Ascidiacea.
• Ascidians forcefully discharge waste and water from the excurrent siphon when irritated.
• Most ascidians are attached to rocks or other surfaces as adults.

Thaliacians (Salps)

• Thalacians, also known as salps, have a barrel-shaped body.

Urochordata Species

• The common characteristics of most Urochordata species as adults include being sessile, filter feeders, and having a sac-like body.