Lecture 15

Question 1

3 major sub-phyla

Answer 1

• Urochordata -> invertebrates (most ancestral)
• Cephalochordata -> more biologically advanced than Urochordata
• Vertebrata -> vertebral column evolves from primitive notochord (composed of vertebral discs)

Question 2

Chordate characteristics?

Answer 2

• most are coelomate, bilateral animals
• presence of a notochord (supports the body; structure)
• nerve cord (runs parallel to notochord)
• gill slits penetrate wall of pharynx
• tail extends past the anus

Question 3

Sub-phylum: Urochordata

Answer 3

• displays all chordate characteristics
• larvae are bilateral swimmers; adults display reversals (no notochord, sessile, etc.)
• most are only a few centimeters long
• filter feeders -> siphon, gill slits, out another siphon

Question 4

Example of a Urochordata?

Answer 4

Sea squirts (tunicates)

Question 5

Sub-phylum: Cephalochordata

Answer 5

• Closest relative to vertebrata
• 3 to 7 cm long
• Body displays chordate features through whole life
• Segmented muscles like vertebrates (called sarcomeres)
• Filter feeders
• Eye spot (used for detecting physical surroundings)

Question 6

Common name for Cephalochordata?

Answer 6

Lancelets

Question 7

What is the purpose of sarcomeres?

Answer 7

Allows for more flexibility

Question 8

Sub-phylum: Vertebrata

Answer 8

• Pharynx completely shifts to gas exchange
• Chambered heart (2 to 3 to 4)
• Tripartite brain (forebrain, midbrain, hindbrain)
• Advanced sensory structures

Question 9

Accessory digestive organs in Vertebrata?

Answer 9

liver (detoxifies body) and pancreas (regulates levels of sugar in body)

Question 10

The primary role of the ____ is to produce hormones.

Answer 10

Endocrine system

Question 11

What are the two classes of Vertebrata?

Answer 11

Myxini (Hagfish; most ancestral) and Petromyzontida (Lamprey; true vertebral column/ first true fish)

Question 12

Characteristics in Myxini?

Answer 12

• No vertebral column
• First group with cranium
• Presence of cartilage (protects brain)
• Sensory tentacles (to find food and tactile organ)
• Low metabolic rates
• Mucus glands produce immense amount of slime

Question 13

Characteristics of Petromyzontida?

Answer 13

• Presence of cranium and vertebrate/ vertebral column
• Teeth made of keratin
• Jawless
• Parasitic
• Small cerebellum (balance and equilibrium)
• 2 pairs of semi-circular canals; decent sight

Question 14

What is the name for the larvae of Lampreys?

Answer 14

Ammocetes

Question 15

Ecological issues with Lampreys?

Answer 15

Harms fish/ infects fish which causes fish sales to decrease and results in fishermen to lose profit