Download • Phylum Chordata • I. General characteristics – A. Notochord (Gr

• Phylum Chordata
• I. General characteristics
– A. Notochord (Gr. Noto =
back, L. chorda = cord)
• 1. A skeletal rod
• 2. All members have a
notochord
• 3. Primary purpose is to
support, stiffen and assist as
a skeletal axis
• 4. Is not always hard
calcified material, but can be
of cartilage
• 5. Usually dorsal to the
organism
• 6. Contains the main nerve
cord in most cases.
– B. Pharyngeal pouches and
slits
• 1. Perforated slitlike
opening
• 2. Present at some stage in
life cycle, but may develop
into another form.
• 3. In lower chordates it
becomes gills or filterfeeding apparatus.
• 4. In tetrapod vertebrates
(four footed), the pouches
develop into Eustachian
tubes, middle ear cavity,
tonsils, and parathyroid
glands.
– The slits form into
pharynx
– C. Postanal tail
• 1. Projects past the anus
during some stages but
disappears in some members.
• 2. In vertebrates without tails
the postanal tail becomes part
of the vertebrate or dorsal
nerve cord.
– D. Muscles are segmented – E. Closed circulatory system
• 1. Dorsal and ventral blood
vessels
– F. Complete and enclosed
digestive system.
– G. Endoskeleton
• 1. Either bone or cartilage
• II. Subphylums
– A. Urochordata ex. tunicates
• 1. 3000 species
• 2. Marine
• 3. Most are sessile with a
few free living.
• 4. Tunic present-calcified
covering open at one end.
• 5. Larval stage bears all
chordate characteristics
except the pharyngeal slits
are not present
• 6. Defense mechanisms-A
jet of water is discharged.
• 7. As adults they have
incurrent and excurrent
siphons for gas exchange
and food getting.
• 8. They are hermaphroditic
or monoecious.
– B. Cephalochordata:
ex. amphioxus
• 1. Slender and laterally
flattened or compressed.
• 2. About 5-7 cm in length
• 3. Live in sandy bottoms of
coastal water worldwide
• 4. 25 species with 4 found in
North America indigenously
(naturally).
• 5. Have all main
characteristics of chordates
at adulthood.
• 6. Pharyngeal slits used for
capturing food.
• 7. Dioecious
• 8. External fertilization
– C. Vertebrata:(fish to human)
• 1. Totally endoskeleton
made up of living cells that
grow with the body.
• 2. Skeleton provides area
for muscle attachment • 3. Skull and thoracic ribs
protect major organs
• 4. In agnathan and sharks
endoskeleton is made up of
cartilage
• 5. Advanced nervous
system including a Central
nervous system (CNS) and
brain
• 6. Paired limbs
– A. pelvic and pectoral
appendages.