Transcript Phylum Chordata Notes

PHYLUM CHORDATA
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Characteristcs of Chordates:
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all chordates have 4 characteristics in common at some point
in their life cycle:
dorsal, hollow nerve tube: in most adult chordates, the
posterior part develops into a spinal cord and the anterior
part develops into a brain
notochord: firm flexible tube just below the nerve
tube(backbone in vertebrates), where muscles can attach
gill slits: paired openings along the pharynx which
functions in filter feeding
post-anal tail: at some point during development, a tail
reaches beyond the anus
The Phylum Chordata Includes:
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Subphylum Cephalochordata (=lancelets)
Subphylum Urochordata (= tunicates)
Subphylum vertebrata:
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Class Agnatha - jawless fish
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Class Amphibia
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Class Aves – birds
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Class Chondrichthyes - cartilaginous fish
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Class Osteichthyes - bony fish
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Class Reptilia
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Class Mammalia
Characteristics of All Vertebrates
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1. have a backbone, which surrounds spinal cord, is made
up of bony segments called vertebrae
2. an endoskeleton which has two main parts:
i. Axial Skeleton: made up of the vertebral column,
skull & rib cage
- supports body and protects spinal column,
brain & other internal organs
ii) Appendicular Skeleton: made of the appendage
bones and wide flattened girdles to which they are
attached
- is attached to axial skeleton
- ex. arms, legs
3. Well developed brain & sensory organs
4. A closed circulatory system
5. Multi-chambered heart
6. Bilateral symmetry
7. Coelomates
8. Efficient respiratory systems
9. Only phylum to have bones
FISHES
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Inhabit nearly every type of
aquatic environment on Earth
Can be grouped into 4 classes:
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Super Class Agnatha:
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1. Class Myxini: hagfish
2. Class Cephalaspidomorphi:
lampreys
3. Class Chondrichthyes:
cartilaginous fish (ex. Sharks &
rays)
 4. Class Osteichythes: bony fish
(ex. Swordfish, tuna, trout…)
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Characteristics of All Fish
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1. breathe using gills
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as a fish takes water in through its mouth, water passes over the gills &
then out through slits at the side of the fish
2. have 2 chambered hearts
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One chamber receives oxygen-poor blood from the body tissues
The other chamber pumps blood directly to the capillaries of the
gills, where oxygen is picked up & carbon dioxide released
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3. reproduce sexually
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Fertilization & development is external in MOST fishes
Eggs & sperm can be released directly into the water, or deposited in
more protected areas
4. highly developed sensory systems
Have eyes that allow them to see objects & contrasts between
light & dark in the water, but the amount of vision varies among fishes
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SUPER CLASS AGNATHA
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jawless fish
lampreys & hagfish
have smooth, scaleless skin & long cylindrical body
Lampreys:
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most are parasites that hitch rides on their hosts, often killing
its host as it sucks out its victim’s body fluids
Hagfish:
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bottom dwellers that spend most of their time hiding in mud
& sand
scavenger that eats fish that are already dead or dying