PHYLUM CHORDATAPHYLUM CHORDATA Characteristcs of Chordates:Characteristcs of Chordates:

all chordates have 4 characteristics in common at some point in their all chordates have 4 characteristics in common at some point in their life cycle:life cycle:

1)1) dorsal, hollow nerve tubedorsal, hollow nerve tube: in most adult chordates, the posterior part : in most adult chordates, the posterior part develops into a spinal cord and the anterior part develops into a braindevelops into a spinal cord and the anterior part develops into a brain

2)2) notochordnotochord: firm flexible tube just below the nerve tube(backbone in : firm flexible tube just below the nerve tube(backbone in vertebrates), where muscles can attachvertebrates), where muscles can attach

3)3) gill slitsgill slits: paired openings along the pharynx which functions in filter : paired openings along the pharynx which functions in filter feedingfeeding

4)4) post-anal tailpost-anal tail: at some point during development, a tail reaches : at some point during development, a tail reaches beyond the anusbeyond the anus

There are actually 3 subphylums of chordates, 2 of There are actually 3 subphylums of chordates, 2 of which are invertebrates)which are invertebrates)

The Phylum Chordata The Phylum Chordata Includes: Includes:

1.1. Subphylum Cephalochordata (=lancelets)Subphylum Cephalochordata (=lancelets)

2.2. Subphylum Urochordata (= tunicates)Subphylum Urochordata (= tunicates)

3.3. Subphylum vertebrata:Subphylum vertebrata:• Class Agnatha - jawless fish Class Agnatha - jawless fish • Class AmphibiaClass Amphibia• Class Aves – birdsClass Aves – birds• Class Chondrichthyes - cartilaginous fishClass Chondrichthyes - cartilaginous fish• Class Osteichthyes - bony fishClass Osteichthyes - bony fish• Class ReptiliaClass Reptilia• Class Mammalia Class Mammalia

Characteristics of All Characteristics of All VertebratesVertebrates

1. have a backbone, which surrounds spinal 1. have a backbone, which surrounds spinal cord, is made up of bony segments called cord, is made up of bony segments called vertebraevertebrae

2. an endoskeleton which has two main parts:2. an endoskeleton which has two main parts:i. i. Axial SkeletonAxial Skeleton: made up of the vertebral : made up of the vertebral

column, skull & rib cagecolumn, skull & rib cage- supports body and protects spinal - supports body and protects spinal

column, brain & other internal organscolumn, brain & other internal organs

ii) ii) Appendicular SkeletonAppendicular Skeleton: made of the : made of the appendage bones and wide flattened girdles to appendage bones and wide flattened girdles to which they are attachedwhich they are attached

- is attached to axial skeleton- is attached to axial skeleton

- ex. arms, legs- ex. arms, legs

3. Well developed brain & sensory 3. Well developed brain & sensory organsorgans

4. A closed circulatory system4. A closed circulatory system

5. Multi-chambered heart 5. Multi-chambered heart

6. Bilateral symmetry6. Bilateral symmetry

7. Coelomates7. Coelomates

8. Efficient respiratory systems8. Efficient respiratory systems

9. Only phylum to have bones9. Only phylum to have bones

FISHESFISHES Inhabit nearly every type Inhabit nearly every type

of aquatic environment on of aquatic environment on EarthEarth

Can be grouped into 4 Can be grouped into 4 classes:classes:

Super Class Agnatha: Super Class Agnatha: 1. Class Myxini: hagfish1. Class Myxini: hagfish 2. Class Cephalaspidomorphi: 2. Class Cephalaspidomorphi:

lampreyslampreys 3. Class Chondrichthyes: 3. Class Chondrichthyes:

cartilaginous fish (ex. Sharks cartilaginous fish (ex. Sharks & rays)& rays)

4. Class Osteichythes: bony 4. Class Osteichythes: bony fish (ex. Swordfish, tuna, fish (ex. Swordfish, tuna, trout…)trout…)

Characteristics of All Characteristics of All FishFish 1. breathe using gills1. breathe using gills

• as a fish takes water in through its mouth, water passes over the as a fish takes water in through its mouth, water passes over the gills & then out through slits at the side of the fishgills & then out through slits at the side of the fish

2. have 2 chambered hearts2. have 2 chambered hearts• One chamber receives oxygen-poor blood from the body tissuesOne chamber receives oxygen-poor blood from the body tissues• The other chamber pumps blood directly to the capillaries of the The other chamber pumps blood directly to the capillaries of the

gills, where oxygen is picked up & carbon dioxide releasedgills, where oxygen is picked up & carbon dioxide released 3. reproduce sexually 3. reproduce sexually

• Fertilization & development is external in MOST fishesFertilization & development is external in MOST fishes• Eggs & sperm can be released directly into the water, or Eggs & sperm can be released directly into the water, or

deposited in more protected areasdeposited in more protected areas 4. highly developed sensory systems4. highly developed sensory systems

• Have eyes that allow them to see objects & contrasts between Have eyes that allow them to see objects & contrasts between light & dark in the water, but the amount of vision varies among light & dark in the water, but the amount of vision varies among

fishesfishes

SUPER CLASS AGNATHASUPER CLASS AGNATHA jawless fishjawless fish lampreys & hagfishlampreys & hagfish have smooth, scaleless skin & long cylindrical have smooth, scaleless skin & long cylindrical

bodybody Lampreys: Lampreys:

most are parasites that hitch rides on their hosts, most are parasites that hitch rides on their hosts, often killing its host as it sucks out its victim’s body often killing its host as it sucks out its victim’s body fluidsfluids

Hagfish:Hagfish: bottom dwellers that spend most of their time hiding bottom dwellers that spend most of their time hiding

in mud & sandin mud & sand scavenger that eats fish that are already dead or scavenger that eats fish that are already dead or

dyingdying