AEBI 211- Chordates

Name characteristics of chordates

• Symmetry

• Axis

• Gut

• Coelom or no coelom

• Body segmentation

• Is there cephalization

• Cleavage

• Blastopore

• Formation of coelom

• Bilateral symmetry

• Anterior-posterior axis

• Complete gut

• Coelom “tube-within-a-tube” arrangement

• Metamerism

• Cephalization

• Radial cleavage

• Anus derived from blastopore

• Coelom formed by enterocoely

How is the coelom in most vertebrates formed?

Schizocoely (secondarily derived)

Protochordata:

a) paraphyletic

b) monophyletic

c) polyphyletic

b)

Subphyla of protochordata

• Urochordata (tunicates)

• Cephalochordata (lancelets)

The subphyla of protochordata are (invertebrates/vertebrates)

Invertebrates

Are protochordata groups part of Craniata

NO, they don’t have cranium or vertebrae

Subphylum urochordata

• Tunicates

• Sessile as adults, some free living

• Have tough nonliving tunic that surrounds animal

• Only larval form bears chordata hallmarks

• Solitary or colonial

Subphylum Cephalochordata

• Lancelets

• Originally bore the generic name Amphioxus

• Amphioxus: Greek, amphi, both ends + oxys, sharp

• Modern survivors of an ancient chordate lineage

• Slender, laterally compressed, translucent animals

• Inhabit sandy sediments of coastal waters

• 5 distinct characteristics of chordates but in simple form