Chordates and Vertebrates

Chordate Characteristics

• notochord

• pharyngeal (gill) slits

• endostyle

• hollow nerve cord

• post anal tail

• bilateral symmetry

• closed circulatory system

notochord

mesoderm

• supports the body (elastic)

• facilitates movement and muscle contractions

pharyngeal slits

• digestive tract chamber

• support gill structures

• facilitate feeding mechanism

endostyle

• iodine-binding

• ciliated to collect food particles

ontogeny

developmental history of an organism (from fertilization)

gastrulation

forms gut and germ layers

neurulation

forms neural tube

organogenesis

forms organs

tissue

group of cells preform a function

organ

group of tissues that preform a function

types of body tissue

• epithelium

• connective

• muscle

• nervous

epithelium tissue

• squamous

• cuboidal

• columnar

• transitional

squamous

flat, irregular

• skin

cuboidal

cube

• glands, digestive, endocrine

columnar

tall, specialized

• digestive system

Transitional

varies between squamous and cuboidal

• urinary bladder

glands

specialized epithelium

• exocrine: product secreted into duct

• endocrine: product secreted into blood

connective tissue

• bone

• cartilage

vertebral column

gradual replacement of notochord → centrum/ vertebral body

cranium “craniates”

• brain encasement

• development of sensory organs

• larger neural tube

agnathans

no jaw

1. hagfish: craniate

2. Lamprey: craniate and vertebrate

chondrichthyes

gnathostome with a cartilaginous skeleton

1. elasmobranch: sharks

2. holocephalans: chimaera

teleostomi - actinopterygii

ray finned fishes with muscle controlling fins

• swim bladder

• bony operculum

• endoskeleton ossification

• bony scales

• otoliths (bony ossicles)

teleostomi - sarcopterygians

• fleshy finned

• give rise to tetrapods (lungfish)

• bony strutcure supports appendages

  • rhipidistians = closest

aminotes

amniotic sac

mammalian evolution

• hair

• mammary gland

mammal phylogeny

1. monotremes (platypus)

2. methetheria (live birth)

3. eutheria (placenta)

mesoderm

• notochord

• dermis

• hypodermis

• muscle

• bone

• connective tissue

ectoderm

• epidermis

• nervous system

endoderm

• gut lining

• organs