Transcript Introduction To Chordates

Introduction To
Chordates
9. Chordata:
Urochordata and
Cephalochordata
James Hake &
Eden Berdugo
What is a chordate?
• Vertebrates are a subphylum of the
phylum Chordata (the chordates)
• Chordates are bilateral
• Belong to a clade of animals known as
Deuterostomia
James Hake & Eden Berdugo
Derived Characteristics of
Chordates
•
•
Notochord
– a longitudinal, flexible rod;
provides flexible skeletal
support
Dorsal Hollow Nerve Chord
– develops into central nervous
system (brain/spinal cord)
http://kentsimmons.uwinnipeg.ca/16cm05/16labman05/lb7pg1_files/34-02ChordateCharacters-L.gif
•Pharyngeal Slits or Clefts
–grooves that develop into slits that open to the outside of the body; used in
gas exchange and feeding
•Muscular, Post-Anal Tail
–A tail extending posterior to the anus that contains skeletal elements and
muscles; propelling force in aquatic species
James Hake & Eden Berdugo
James Hake & Eden Berdugo
Tunicates (subphylum
Urochordata)
Sea Tulips
http://en.wikipedia.org/wiki/File:Sea-tulip.jpg
Bluebell Tunicates
http://upload.wikimedia.org/wikipedia/commons/9/98/Blu
ebell_tunicates_Nick_Hobgood.jpg
Categories
• Body Cavity
– Coelemate
– Body cavity lost in adults
• Body symmetry
– Bilateral
• Nervous System
– Simple brains with ganglion clusters
• Circulatory System
– Closed circulatory system in which
blood is transported
– Blood circulation powered by heart
http://www.mun.ca/biology/scarr/142007_Urochordata.jpg
James Hake & Eden Berdugo
Categories [Continued]
• Digestive System:
– Suspension feeders; feed
by filtering sea water
through pharyngeal slits,
where food gets caught in
a mucus lining
– Two openings in body
cavity: in-current and excurrent siphon
• Excretory System
– None
• Locomotion/Musculature
– Sperm are mobile, but
adults are immobile
• Skeletal Type
– None
– Invertebrate
http://www.mun.ca/biology/scarr/142007_Urochordata.jpg
James Hake & Eden Berdugo
Categories [Continued]
• Sensory Structures
– Light/gravity sensing cells in
the larvae
• Reproduction
– Hermaphrodites (ie asexual
reproduction)
• Gas Exchange
– Absorb through pharynx
• Unique Features
– As larvae, they move around
until they find a suitable
environment to become
permanently fixed to.
http://www.mun.ca/biology/scarr/142007_Urochordata.jpg
James Hake & Eden Berdugo
Urochordata Review
Adult Tunicate
Larvae Tunicate
http://www.mun.ca/biology/scarr/142007_Urochordata.jpg
James Hake & Eden Berdugo
Cephalochordata
(Lancelets)
Branchiostoma
http://www.bethel.edu/~johgre/bio114d/LowerVerts.html
http://www.mun.ca/biology/scarr/142007_Urochordata.jpg
James Hake & Eden Berdugo
Categories
• Body Cavity
– Coelomate
• Body Symmetry
– Bilateral Symmetry
• Nervous System
– Dorsal, hollow nerve cord
– Hox genes control
development of brain
– No full-fledged brain; only
have swollen tip on the
anterior end of the nerve
cord
• Circulatory System
– Contains heart
– Closed Blood System
http://www.mun.ca/biology/scarr/Cephalochordata.html
James Hake & Eden Berdugo
Categories [Continued]
•
•
•
•
Digestive System
– Use pharyngeal slits lined with
mucous to remove tiny food
particles
Excretory System
– Composed of paired nephridia (a
tubule open to the exterior; has
ciliated or flagellated cells and
absorptive walls)
Locomotion/Musculature
– Simple swimming mechanism
– Coordinated contractions of
muscles in chevrons (<<<)
produce movement
– Muscle segments called somites
Skeletal Type
– No solid skeleton, but has flexible
notochord
– Invertebrate
http://www.mun.ca/biology/scarr/Cephalochordata.html
James Hake & Eden Berdugo
Categories [Continued]
• Sensory Structures
– Poorly developed
• Reproduction
– Separate Sexes
– Males and females have
multiple paired gonads
– External Fertilization
• Gas Exchange
– Pharynx and pharyngeal slits
aid gas exchange, which occurs
across the external body
surface
• Other Unique Features
– Lancelets’ bodies aren’t hard,
so little fossil evidence
– Adult lancelets live in the sand
with their anterior ends exposed
to remove tiny food particles
http://www.mun.ca/biology/scarr/Cephalochordata.html
James Hake & Eden Berdugo
A Review of Cephalochordata
(Lancelets)
http://www.bethel.edu/~johgre/bio114d/LowerVerts.html
James Hake & Eden Berdugo
Quiz
1.
A.
B.
C.
D.
Which is not a characteristic of all chordates?
Notochord
Radial Symmetry
Nerve Cord
Pharyngeal Slits
2. True or false: Urochordates are mobile throughout their entire
lives.
James Hake & Eden Berdugo
3. Urochordates and cephalochordates feed by:
A. Chemosynthesis
B. Photosynthesis
C. Pharyngeal Slits and Clefts
D. All of the Above
4. Regarding their notochords…
A. Urochordates keep theirs for their entire lives, and
Cephalochordates do not.
B. Cephalochordates keep theirs for their entire lives, and
Urochordates do not.
C. Both Urochordates and Cephalochordates do NOT keep
theirs for their entire lives.
D. Both Urochordates and Cephalochordates keep theirs for
their entire lives.
James Hake & Eden Berdugo
Answers
1.
2.
3.
4.
B
False
C
B
James Hake & Eden Berdugo