1. Chapter 23 Phylum Chordata
Sub-phyla: Urochordata, Cephalochordata & Vertebrata
Superclasses: Agnatha & Gnathostomata

4. Five Chordate Hallmarks
A. Notochord
B. Dorsal Tubular Nerve Cord
C. Pharyngeal Slits
D. Endostyle or Thyroid
E. Post Anal Tail

5. Five Chordate Hallmarks
Notochord
Longitudinal flexible rod extending the length of the body
It is present throughout the life of jawless vertebrates
In most adult vertebrates, it is replaced by cartilage or bone vertebrae although it may remain between or within the vertebrae

6. Lamprey

7. Five Chordate Hallmarks
Dorsal Tubular Nerve Cord
Nerve cord lies dorsal to the alimentary canal
The anterior end becomes enlarged to form the brain and the remainder becomes the spinal cord

8. Five Chordate Hallmarks
Pharyngeal Slits or Pouches
Opening that lead from the pharyngeal cavity to the outside
In tetrapods, the pharyngeal pouches give rise to a variety of structures including the Eustachian tubes, parathyroid glands, tonsils and middle ear cavity
In fish, the structures become fully functioning gills used in respiration and filter feeding in some

9. Pharyngeal Slits in Sharks & Lamprey

10. Five Chordate Hallmarks
Endostyle or Thyroid Gland
The endostyle or thyroid gland is a recent addition as a chordate characteristic
In primitive chordates, the endostyle functions to secrete mucous and aids the pharynx in filter feeding
In higher vertebrates, the thyroid secretes iodinated hormones that regulate metabolism
Typically located in the pharyngeal area of the body

11. Five Chordate Hallmarks
Post Anal Tail
Skeletal & muscular elements that extend past the anus
In most vertebrates, it remains as a waggable tail which is useful in balance, propulsion, mobility, etc
In humans and some apes, it has become reduced to a few bones at the bottom of the sacrum called the coccyx

13. Phylum Chordata Sub-PhylumUrochordata (means “tail cord”)
About 3000 species commonly called sea squirts
Adults are sessile and produce a tough outer layer called a tunic
Only sea squirt tadpole larva are motile and exhibit all the chordate hallmarks

14. Phylum Chordata Sub-Phylum Cephalochordata (means “head-cord”)
Lancets are slender, flattened, translucent animals about 5-7 cm long
About 25 species are found on sandy bottoms of coastal waters around the world
Commonly called amphioxus, it shows all the hallmark characteristics in simple form
They are considered a sister form and not an ancestor of the vertebrates

15. Lancet

16. Phylum Chordata
Sub-Phylum Vertebrata (means “back bone”) divided into two Superclasses
Superclass Agnatha (means “without jaws”)
Superclass Gnathostomata (means “jawed mouth”)

17. Phylum Chordata Subphylum Vertebrata Superclass Agnatha – 2 classes
Class Myxini (means “slime”)
There are 65 species of hagfish
They are scavengers &/or predators that feed on annelids, mollusks, crustaceans, and dead or dying fish
They have sensory tentacles called barbels used to locate food
Sense organs of touch, taste, and smell, but no eyes so they are virtually blind
Two keratinized plates rasp away flesh from its prey
Can secrete enormous amounts of slime when disturbed thus making them impossible to hold

18. Phylum Chordata
Class Myxini – 65 species of hagfish

19. Phylum Chordata Subphylum Vertebrata Superclass Agnatha – 2 classes
Class Cephalaspidomorphi (means “head shield / body”)
There are 22 species of lampreys
Their larval form are called ammocoetes and resembles amphioxus
Amphioxus

20. Phylum Chordata Superclass/Sub-phylum Agnatha – 2 classes
Class Cephalaspidomorphi (means “head shield / body”)
(con’t)
They remain in freshwater, filter-feeding stage for 3-7 years
Adults can be 15 cm to 60 cm in length
They may be parasitic or non-parasitic depending upon the individual species
They have 7 pairs of gills that are non-ventilated with water from the mouth
Sense organs for touch, taste, smell and well developed eyes
Parasitic adults attach to prey with sucker-like mouth and bore a hole in the flesh with their sharp keratinized teeth
Non-parasitic adults do not feed as adults, thus they spawn and die within a few months.

21. Phylum Chordata Superclass Gnathostomata – seven classes
Class Chondrichthyes (means “cartilage fish”)
Example Sharks

22. Phylum Chordata Superclass Gnathostomata – seven classes
Class Actinopterygii (means “modern bony fish”)
Example - Tuna

23. Phylum Chordata Superclass Gnathostomata – seven classes
Class Sarcopterygii (means “lobe-finned”)
Example Coelacanth and lungfish

24. Phylum Chordata Superclass Gnathostomata – seven classes
Class Amphibia -(means “double life”)
Example - Frogs

25. Phylum Chordata Superclass Gnathostomata – seven classes
Class Reptilia means
(“to creep”)
Example – Snakes, Turtles, Lizards

26. Phylum Chordata Superclass Gnathostomata – seven classes
Class Aves means (“to fly”)
Example - Birds

27. Phylum Chordata Superclass Gnathostomata – seven classes
Class Mammalia means “(breast animal”)
Example – humans, horses, dogs, dolphin

28. Phylum Chordata Class Vertebrata General Characteristics:
Highly specialized tripartite brain which is encases in a protective skull with 12 pairs of cranial nerves
Backbone which is encloses a nerve cord The vertebrae are grouped into five regions-33 total vertebra
Cervical (neck)-7 vertebra
Thoracic (chest) -12 vertebra
Lumbar (back)-5 vertebra
Sacral (pelvic)- 5 fused vertebra
Caudal (tail)-4 partially fused vertebra

30. Phylum Chordata Class Vertebrata General Characteristics: (con’t)
Endoskeleton composed of bone or cartilage or a combination of both
Axial skeleton includes the bones of the skull, ribs and backbone
Appendicular skeleton includes the bones of the arms and legs
Pectoral Girdle located anteriorly and attached to the forelimbs
Pelvic Girdle located posteriorly and attached to the hind limbs

31. Axial Skeleton

32. Appendicular Skeleton

33. Pectoral Girdle

35. Phylum Chordata Class Vertebrata General Characteristics: (con’t)
Paired sense organs specialized for sensing vibrations in water called a “lateral line”
Well developed and complex nervous system
CNS – Central Nervous System – made up of the brain & spinal cord
PNS – Peripheral Nervous System – made up of the nerves that connect to the organs, muscles, and epidermis

37. Phylum Chordata Class Vertebrata General Characteristics: (con’t)
4-legged = tetrapod
5-digits = pentadactyl