1. PHYLUM
CHORDATA

2. PHYLUM CHORDATA Characteristcs of Chordates:
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
There are actually 3 subphylums of chordates, 2 of which are invertebrates)

3. The Phylum Chordata Includes:
Subphylum Cephalochordata (=lancelets)
Subphylum Urochordata (= tunicates)
Subphylum vertebrata:
Class Agnatha - jawless fish
Class Amphibia
Class Aves – birds
Class Chondrichthyes - cartilaginous fish
Class Osteichthyes - bony fish
Class Reptilia
Class Mammalia

4. Characteristics of All Vertebrates
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

5. 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

6. FISHES Inhabit nearly every type of aquatic environment on Earth
Can be grouped into 4 classes:
Super Class Agnatha:
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…)

7. Characteristics of All Fish
1. breathe using gills
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
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
3. reproduce sexually
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

8. SUPER CLASS AGNATHA jawless fish lampreys & hagfish
have smooth, scaleless skin & long cylindrical body
Lampreys:
most are parasites that hitch rides on their hosts, often killing its host as it sucks out its victim’s body fluids
Hagfish:
bottom dwellers that spend most of their time hiding in mud & sand
scavenger that eats fish that are already dead or dying