Phylum Chordata
Sub-phyla: Urochordata, Cephalochordata & Vertebrata
Superclasses: Agnatha & Gnathostomata
Five Chordate Hallmarks
 A. Notochord
 B. Dorsal Tubular Nerve Cord
 C. Pharyngeal Slits
 D. Endostyle or Thyroid
 E. Post Anal Tail
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
Lamprey
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
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
Pharyngeal Slits in Sharks & Lamprey
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
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
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
Phylum Chordata
 Sub-Phylum Cephalochordata (means “head-cord”)
 Lancets are slender, flattened, translucent animals about 57 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
Lancet
Phylum Chordata
 Sub-Phylum Vertebrata (means “back bone”)
divided into two Superclasses
 Superclass Agnatha (means “without jaws”)
 Superclass Gnathostomata (means “jawed mouth”)
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
Phylum Chordata
 Class Myxini – 65 species of hagfish
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
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.
Phylum Chordata
 Superclass
Gnathostomata –
seven classes
 Class Chondrichthyes
(means “cartilage
fish”)

Example Sharks
Phylum Chordata
 Superclass Gnathostomata – seven classes
 Class Actinopterygii (means “modern bony fish”)

Example - Tuna
Phylum Chordata
 Superclass Gnathostomata – seven classes
 Class Sarcopterygii (means “lobe-finned”)

Example Coelacanth and lungfish
Phylum Chordata
 Superclass
Gnathostomata –
seven classes
 Class Amphibia -
(means “double
life”)

Example - Frogs
Phylum Chordata
 Superclass
Gnathostomata –
seven classes
 Class Reptilia
means
 (“to creep”)

Example –
Snakes, Turtles,
Lizards
Phylum Chordata
 Superclass
Gnathostomata –
seven classes
 Class Aves means
(“to fly”)

Example - Birds
Phylum Chordata
 Superclass
Gnathostomata –
seven classes
 Class Mammalia
means “(breast
animal”)

Example – humans,
horses, dogs,
dolphin
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
1.
Cervical (neck)-7 vertebra
2.
Thoracic (chest) -12 vertebra
3.
Lumbar (back)-5 vertebra
4.
Sacral (pelvic)- 5 fused vertebra
5.
Caudal (tail)-4 partially fused vertebra
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
Axial Skeleton
Appendicular Skeleton
Pectoral
Girdle
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
Phylum Chordata
 Class Vertebrata
 General
Characteristics: (con’t)
 4-legged = tetrapod
 5-digits = pentadactyl