Lab 6: Vertebrate Origins & Design

Question 0

Phylum Hemichordata includes what classes and species?

Answer 0

Acorn worms - Class Enteropneusta

Pterobranches - Class Pterobranchia

Question 1

What are 5 unique characteristics of Phylum Chordata?

Answer 1

1) a notochord (spine structure)
2) a dorsal hollow nerve chord (spinal chord)
3) pharyngeal slits
4) endostyle (thyroid)
5) post-anal tail

Question 2

Phylum Chordata contains

Answer 2

Subphylum Urochordata

Subphylum Cephalochordata

Subphylum Craniata

Question 3

Phylum Urochordata

Answer 3

“Tail-chord”
Tunicates

• Have complex pharynx for filter feeding
• Notochord and nerve chord in larvae only (explains why paedomorphosis is thought to be the transitional form)

Question 4

Tunicates

Answer 4

A sea squirt!

Sessile or planktonic filter feeders
Reproduce externally
Tadpole like larva metamorphosis to mature adult

Question 5

Paedomorphosis

Answer 5

The process of sexual maturation of a larval form to a mature adult form. Believed to occur in tunicates.

Question 6

Subphylum Cephalochordata

Answer 6

(Amphioxus) lancelets

Question 7

Lancelets

Answer 7

Burrow in sandy marine substrates
Filter feeders
Free swimming larvae

Question 8

Characteristics of Hemichordates

Answer 8

1) ciliated pharyngeal slits
2) open circulatory system
3) complete gut
4) no kidney- glomerulus connected to blood vessels has an excretory function
5) separate sexes and external fertilization
6) marine only
7) larvae similar to sea star
8) most important: tubular dorsal nerve cord representing an early transition to a spinal cord.

Question 9

Parts of a lancelet to know:

Answer 9

Pharynx 
Gill slits 
Gill bars
Myotome
Right dorsal aorta
Notochord 
Dorsal ventral nerve chord

Question 10

Subphylum Craniata

Answer 10

Infra Phylum Hyperotreti

Infra Phylum Vertebrata

Question 11

Infra phylum Hyperotreti

Answer 11

Class Myxini - hagfishes

Eat decaying organisms by entering through the animals mouth

Secret tons of slime through slime glands as predator defence.

Question 12

Infra phylum Vertebrata

Answer 12

Lamprey

• bottom dwellers
• parasitic with fish

Question 13

Lamprey larvae

Answer 13

Ammocoete larvae

• superficially look like amphioxus (lancelets) but they have a pituitary gland and chambered heart plus complex brain and sensory functions

Know these parts:

• pharynx with gill pouches
• forebrain
• endostyle
• myotome
• notochord
• dorsal ventral nerve chord (spinal chord)

Question 14

Lamprey skin

Answer 14

EPIDERMIS: Has epithelial cells with no scales, no keratin.

DERMIS: Has chromatophores as pigment cells and collagenous connective tissue

HYPODERMIS: adipose tissue

Question 15

Cartilage

Answer 15

Connective tissue between bone

1) skeletal support
2) cushioning between joints
3) absorbs and stores mechanical energy during locomotion

Chondrocytes inside of a
Lacuna (olive shape) inside a
Collagen matrix

Endochondral bone develops in cartilage.

Question 16

Bone

Answer 16

Structural support

Osteocytes = bone cells
Osteons = rings around interconnected with blood vessels 

Dermal bone develops in the skin

Question 17

Skeletal muscle (striated muscle)

Answer 17

• striated
• multinucleate
• nucleus are on sides not middle
• involuntary muscle movements

Question 18

Smooth muscle

Answer 18

• one nucleus per plasma membrane
• little bubbles with cytoplasm all around
• involuntary

Question 19

Cardiac muscle

Answer 19

• Looks like random branches
• intercalated discs are long lines that break up the branches
• some striations
• nucleus in middle
• involuntary

Question 20

Lamprey have all components of vertebrate digestive system?

Answer 20

• no gizzard
• no liver
• no gallbladder