1. Phylum Chordates

2. Characteristics Characteristics similar to other phylum discussed:
Bilateral symmetry
Triploblastic
Well-developed coelom
Metameric- Segmented body
“tube within a tube” arrangement
Cephalization

3. Characteristics Deuterostome Radial clevage Anus forms first
Primitively Enterocoelous
Early chordates were known to be enterocoelous, however, due to the large yolk of modern species, most vertebrates are schizocoelus

4. Characteristics
5 distinctive characteristics that set chordates apart from all other phyla:
Notocord
Dorsal tubular nerve cord
Pharyngeal pouches or slits
Endostyle
Postanal tail

5. 1. Notocord
All members of this phylum contain a notochord (noton, back + chorda, cord)
Can be restricted to early development or may be present throughout life
Rod like, semi rigid body of cells enclosed by a fibrous sheath, which extends the length of the body just ventral to the central nervous system.
Primary purpose is to stiffen the body, providing skeletal scaffolding for the attachment of swimming muscles

6. 2. Dorsal Tubular Nerve Cord
Solid, single nerve cord is dorsal to the alimentary canal and is a tube
Hollow center
Anterior end becomes enlarged to form the brain

7. 3. Pharyngeal Pouches and Slits
Slit openings
Give rise to several structures:
Middle ear cavity
Tonsils
Parathyroid glands
Eustachian tube (equalizes pressure between ear and nasal canal, surrounding ear drum)
Gills

8. 4. Endostyle or Thyroid Gland
Endostyle- secretes mucus that traps small food particles
Work together with hormone secretion

9. 5. Postanal Tail End of the notochord (stiffened)
Used primitively for swimming
Humans have evidence of the tail but evidently it is vestigal (the coccyx, tail bone)

10. Divisions of the Phylum Chordata
Protochordata (Acraniata)- lack a well-developed head
Subphylum Urochordata
Tunicates
Subphylum Cephalochordata
Lancelets
Vertebrata (Craniata) – has a well-developed head
Tunicates

11. Divisions of the Phylum Chordata
Agnatha- vertebrates lacking jaws
Hagfishes and lampreys
Gnathostomata- Vertebrates having jaws
All other vertebrates
Two forms
Pisces- jawed vertebrates with appendages
Tetrapoda- jawed vertebrates with appendages in the form of limbs
Amniota- vertebrates whose embryos develop within a fluid-filled sac
Reptiles, birds, mammals
Anamniota- vertebrates lacking this adaptation
Fishes and amphibians

12. Phylum Chordates
EVOLUTION

13. Subphylums There are 3 subphylum belonging to the phylum Chordata
Remember we have already discussed two:
Protochordata (lack a well-developed head)
Subphylum Urochordata (tunicates)
Subphylum Cephalochordata (lancelets)

14. Further Divisions Subphylum Vertebrata (have a well-developed head)
Super class Agnatha (lack Jaws)
Class Myxini (hagfish)
Class Petremyzontida (lampreys)
Super Class Gnathostomata (have jaws)
Pisces (Jaws with appendages)
Class Chondrichthyes (cartilaginous fishes)
Osteichthyes (boney fishes)
Class Actinopterygii (ray-finned fishes)
Class Sacropterygii (lobe-finned fishes)
Tetrapoda (Jaws with appendages as limbs)
Class Amphibia
Class Reptilia
Class Aves
Class Mammalia

15. New Evolutionary Tree Must include when the following traits emerged:
Protochordata
Vertebrata
Agnatha
Gnathostomata
Pisces
Tetrapoda
Use pg 499 in your text book as a reference
Also include the Phylum Echinodermata
Use front cover and pg 473
Save room for Subclasses, Orders and Suborders