Peteromyzontida

Question 1

Give the common species of this group.

Answer 1

Lampreys

Question 2

What is special about the northern lampreys chromosomes ?

Answer 2

They have the highest number of chromosomes among vertebrates

Question 3

Give the key features of the lampreys

jaws, skeleton, fins

Answer 3

Jawless
Cartilaginous segments surround the nerve chord
caudal tail (propulsion) and dorsal fins

Question 4

They are the youngest lineage of vertebrates.

True or False ?

Answer 4

False, They are the oldest living lineage.

Question 5

Describe the life cycle of Lampreys.

Answer 5

When juvenile, live in streams.
Emerge from stream bed and migrate downstream to lakes.
DIADROMOUS (Fresh and salt water lifecycle)
Once mature at 5 years, begin parasitic life cycle.
Migrate into streams, spawn
ANADROMOUS- breed in fresh water.
SEMELPARITY- Breed once and then die.

Question 6

Define 
DIADROMOUS 
ANADROMOUS
SEMELPARITY
CATADROMOUS

Answer 6

D, Fresh and salt water lifecycle
A, Born in fresh water, spends life in sea. Breeds in Fresh water
S, Breed only once before death
C, Born in seawater, spends life in fresh water, Breed in seawater

Question 7

Describe the process of Lamprey respiration

Answer 7

Use pharyngeal slits and tidal respiration to breathe.
Water is pumped half way in and out
O2 used for respiration

Question 8

How do larval lampreys feed ?

Answer 8

Using sticky secretions from the endostyle

Question 9

What is the endostyle ?

Answer 9

A ciliated groove which aids feeding.
An Apomorphy of chordates
It produces iodine

Question 10

What is the endostyle homologous with in the human body ?

Answer 10

Thyroid gland, regulating growth.

Question 11

What is an Apomorphy ?

Answer 11

A unique derived feature of a specific group.