Lecture 2--Chordates and Vertebrates

What are the five characteristics shared by all chordates?

1. Notochord

2. Pharyngeal/gill slits

3. Endostyle

4. Dorsal hollow nerve tail

5. Post-anal tail

What are the two additional characteristics shared by all vertebrates?

Bilateral symmetry and closed circulatory system

What is the function of the notochord?

Provides support to body and facilitates movement/muscle contractions

What embryonic layer does the notochord originate from?

Mesoderm

What is the function of the pharyngeal slits?

Support gill structures and facilitate feeding mechanism

Where are the pharyngeal slits located in chordates?

Posterior to mouth

Which organ is the endostyle located in?

Pharynx

What is the function of the endostyle?

Moves food particles to GIT with cilia (lower vertebrates), becomes thyroid (higher vertebrates)

What is ontogeny?

Developmental history of an organism from fertilization

What is the process where a zygote rapidly divides?

Cleavage

What are the stages of zygote development?

Zygote → morula → blastula

What is gastrulation of the blastula?

Formation of gut, germ layers

What is neurulation of the blastula?

Formation of the neural tube

What are the three germ cell layers?

Ectoderm, mesoderm, endoderm

What does the ectoderm develop into?

Exoskeleton, skin, appendages, nervous system

What does the mesoderm develop into?

Organs, bone and cartilage, muscles, vasculature

What does the endoderm develop into?

Inner lining of organs, GI tract, respiratory tract, bladder, urethra, liver

What are the four types of tissue in the body?

Epithelium, connective tissue, muscle, nervous

What are the four types of epithelium?

Squamous, cuboidal, columnar, transitional

What is transitional epithelium?

Between squamous and cuboidal

What type of epithelium is this?

Squamous

What type of epithelium is this?

Cuboidal

What type of epithelium is this?

Columnar

What type of epithelium is this?

Transitional

What do exocrine glands secrete into?

Ducts

What do exocrine glands secrete into?

Blood

What are the two types of connective tissue?

Bone and cartilage

What is phylogeny?

Course of evolutionary change within related groups/organisms

Vertebrates have all chordate characteristics plus:

Vertebral column (replaces notochord), cranium

What are agnathans?

Jawless vertebrates

What is a craniate?

Chordate with a head containing a brain, eyes, and sensory organs

What do agnathans have to draw in food/water?

Muscular pharyngeal pump

What is a gnathostome?

Chordate with a jaw

What is the benefit of gnathostomes having a jaw?

Removes prey size limitations

What is the type of gnathostome that has bony armor?

Placoderms

What is a placode?

Embryonic structure that gives rise to other structures

What are the two types of gnathostomes?

Chondrichthyes and teleostomi

What is the type of gnathostome that has a cartilaginous skeleton?

Chondrichthyes

What are the two modern groups of chondrichthyes?

Elasmobranch (sharks, rays) and holocephalans (chimaera)

What type of teleostomi contains ray-finned fishes?

Actinoptergii

What is a special feature of actinopterygii?

Otoliths

What type of teleostomi contains fleshy-finned fish and gives rise to tetrapods?

Sarcopterygians

What are amniotes?

All terrestrial vertebrates except Amphibia → embryos enveloped in extra-embyronic membranes

What are the two characteristics shared by all mammals?

Hair, mammary gland

What order of mammals contains egg-laying animals?

Monotremes

What order of mammals contains marsupials (early birth)?

Metatheria

What order of mammals contains placentals?

Eutheria