Bio 123: PP15 Material

Question 1

What are the 4 key characteristics of Chordates?

Answer 1

1) There is a presence of notochord
2)The nerve cord runs parallel with the notochord and gut, anterior end develops into the brain
3)Gill slits penetrate the wall of a pharynx (at least at some point in embryological development)
4) Tail extends past the anus (at least at some point of their development)

*** All of these features are present is chordate embryos

Question 2

Do all vertebrata have vertebrates?

Answer 2

NO

Question 3

What are 2 basic characteristics of Chordates?

Answer 3

They are coelomate and demonstrate bilateral symmetry.

Question 4

What is the Notochord?

Answer 4

It is a rod of stiffened, but flexible, tissue that helps support the body.

The notochord also later develops into the vertebral column

Question 5

What are some characteristics of the bodily systems of chordates?

Answer 5

-They have a defined central nervous system
-The pharynx moves from a digestive tract to a respiratory organ

Question 6

What are the 3 major sub-phyla of chordates?

Answer 6

1) Urochordata (invertebrates)
2) Cephalochordata (invertebrates)
3) Vetebrata

Question 7

What is a distinguishing characteristics of the vetebrata?

Answer 7

The vertebral column evolves from primitive notochord, composed on individual vertebral bones and are separated by disks (ligaments)

Question 8

What is the common name for Urochordata?

Answer 8

They are known as sea squirts or tunicates.

Question 9

What are the characteristics of Urochordata?

Answer 9

-Is the most ancestral sub-phylum of chordates.
-They begin as bilateral larvae swimmers
-Adults display evolutionary reversals
-They have a jellylike tunic around the pharynx
-Most are a few centimeters long
-Live in a variety of aquatic habitats
-Are filter feeders and have an incurrent and outcurrent siphon, gill slits
-The pharynx is a respiratory organ as well
-Gas exchange is done through diffusion

Question 10

What are some reversals that we see in adult Urochordates?

Answer 10

-Their tail is reabsorbed
-They take on more of a radial symmetry
-Their nerve cord is absorbed into their body
-They gather oxygen through diffusion
-Have a basic circulatory system

Question 11

What is the tunicate?

Answer 11

The larva form of urochordates

Question 12

What are the characteristics of Cephalochordata?

Answer 12

-Closets relatives to Vertebrata
-Only 3-7 cm long
-Body display all chordate features throughout their life
-Have a head and a simple brains with neurons
-Have segmented muscles
-Are filter feeders
-Nerve cord sits dorsal to the notocord
-Tail is used for balance

Question 13

What are some major body characteristics of Cephalochordata?

Answer 13

-Have an eyespot
-Tentacle like structures around the mouth
-Dorsal tubular nerve cord
-Notocord
-Pharynx with gill slits
-tail extending past anus

Question 14

What are the myomeres?

Answer 14

They are each segmented muslce

Question 15

What are the characteristics of Vertebrata?

Answer 15

-Pharynx completely shifts to gas exchange
-Accessory digestive organs such as the liver and pancreas
-Have chambered hearts
-Have tripartite brain
-Have advanced sensory structures (increased cephalization)
-Have an affinity for oxygen in red blood cells (hemoglobin)
-Have kidneys
-Have an endocrine system

Question 16

What does tripartite brain mean?

Answer 16

That the brain have a forebrain, midbrain, and hindbrain

Question 17

What is the purpose of the liver in vertebrata?

Answer 17

It secretes bile and metabolizes protein, fats, and other substances

Question 18

What is the purpose of the pancreas?

Answer 18

It regulates sugar levels in the blood

Question 19

Define emulsification

Answer 19

The process in which large lipid globules are broken down into smaller lipid globules.

Question 20

What classes fall under the sub phylum Vertebrata?

Answer 20

Myxini (Hagfish)
Petromyzontida (lamprey)

Question 21

What is the ancestral state of hearts?

Answer 21

Having 2 chambers

Question 22

What is the derived state of hearts?

Answer 22

Having 4 chambers (Birds and mammals have 4 heart chambers)

Question 23

Excretory system

Answer 23

Is made of individual units known as nephrons that filter the blood and get rid of waste (bladder and kidneys included)

Question 24

What is a unique characteristics of Myxini?

Answer 24

They are the most ancestral class within the vertebrata and their new characteristic is that they have a cranium

Question 25

What is the earliest cranium made out of?

Answer 25

Cartilage

Question 26

What are the characteristics of Myxini?

Answer 26

-Known as hagfish
-Do not have a true vertebral column
-First group with a cranium
-Cartilage protects their brain (no bone yet)
-Less that a meter long
-Nearly blind
-Finds found through sensory tentacles
-Are relatively sessile and have low metabolic rates
-unique predatory defenses
-Closely related to lamprey and have jawless lineages

Question 27

Define the cranium

Answer 27

It is a hardened structure made out of cartilage that protects the brain.

Question 28

What is the defense mechanism of hagfish?

Answer 28

They excrete a thick slime into the environment that basically clogs the gills of its predators which causes them to suffocate and die.

Question 29

What is a new characteristic found in Petromyzontida?

Answer 29

Their new characteristic is that they have a true vertebral column

Question 30

What are the characteristics of Petromyzontida (lampreys)?

Answer 30

• Become distinct due to the presence of a vertebrate (First true vertebrates)
  -Are jawless
  -Are parasitic
  -Have a small cerebellum
  -Have sensory structures such as eyes well, two-pairs of semicircular canals
  -Well established in great lakes
  -Defined CNS

Question 31

What is the purpose of the cerebellum?

Answer 31

Responsible for balance and equillibrium

Question 32

What are ammocoetes?

Answer 32

The larvae of petromyzontida (hagfish)

Question 33

What is the life cycle of hagfish?

Answer 33

-M/F hagfish seek out riffle areas and create a crescent shaped nests with gravel and small stones
-They place their fertilized eggs among the gravel which hatch a few weeks later
-Larvae emerge from the nests and drift downstream.
-These larvae will burrow into silt and will remain there for 3-5 years until they mature.
-adult parasites will leave silt as sea lampreys and feed on fish.

*** each adult lamprey will spend 12-18 months in the lakes and destroy up to 40 pound of fish.

Question 34

What are the ecological issues with hagfish?

Answer 34

Hagfish are a highly invasive species and they are causing a decline in the fish population in great lakes. It has commercial affects because fishing companies cannot take to market fish that have been bitten and there is a decrease in fish population.

Question 35

What are the teeth of hagfish made out of?

Answer 35

Keratin

Question 36

Explain the semicircular canals

Answer 36

Sensory structures that are the earliest development of ear canals

Question 37

Vertigo

Answer 37

Sensation of feeling dizzy

Question 38

Invasive species

Answer 38

Any species that moves into a havitat that is not native to them and they over compete against the native species

Question 39

What are some physical features of hagfish?

Answer 39

-Eye
-Nostril
-Buccal tunnel
-External gill slits
- Anterior dorsal fin
-Caudal fin
-Tail
-Cloacal aperture

Question 40

Lampricide

Answer 40

A pesticide used to try to control sea lamprey populations. This pesticide specifically targets the larval stage of the sea lamprey.