Classification

Question 1

Explain the categories of chordates and what the chordata is?

Answer 1

Phylum chordata
3 subphyla = Urochordata (tunicates)
Cephalochordata (Amphioxus)
Craniata (hagfish, vertebrates)

Question 2

What are 5 synapomorphies of chordates?

Answer 2

1. Pharyngeal pouches - occur early in development and become certain things (gills in fish)
2. Endostyle (groove in pharynx) - thyroid gland in higher verts
3. Notochord - fibrous tissue (like cartilage) that acts as support on dorsal side
4. Nerve cord dorsal to notochord - anterior part can become well developed brain
5. Larva/embryo w/ post anal tail

Question 3

What are the characteristics of tunicates?

Answer 3

Sessile, filter feeders. Mobile in larval stage

Question 4

What are the characteristics of amphioxus?

Answer 4

Lives in sand, filter feeds from marine environment. Notochord is retained into adulthood

Question 5

What are some characteristics of craniates?

Answer 5

Cranium - specialized connective tissue structure to support and protect the brain
Cephalization

Question 6

What are some synaphomorphies of craniates?

Answer 6

Neural crest
Brain case
Differentiated digestive system
Muscularization of gut tube wall
Multichambered heart
Tripartite brain
Complex endocrine system
Hemoglobin

Question 7

What are gnathostomes? Who count as them?

Answer 7

Gnathostomes = jaws

Everything except agnathans

Question 8

How many species are there in each class?

Answer 8

Agnatha - 120
Chondrichthyes - 1000
Osteichthyes - 29000
Amphibia - 6500
Reptilia - 8200
Aves - 10000
Mammals - 5500

Question 9

Explain the timeline.

Answer 9

COSDCP, TJC

1st Chordates
1st Vertebrates
1st Jawed fishes
1st tetrapods
1st amniotes (reptiles)
1st dinosaurs
1st mammals
1st birds
extinction of dinosaurs