Class Turbellaria (Planarians)

Question 1

Habitat

Answer 1

Mostly freshwater
Few terrestrial

Question 2

Body characteristics

Answer 2

Flat
Slender
Ribbon or leaf like bodies

Question 3

Feeding & Digestion

Answer 3

Incomplete digestive tract
Some have more than 1 mouth and pharynx
Mainly carnivorous

Question 4

Nervous system & senses

Answer 4

Cephalic ganglia
Pair of ventral nerve cords
Some contain statocysts for reacting to gravity

Question 5

Excretory system

Answer 5

Protonephridia with flame cells

Question 6

Asexual reproduction

Answer 6

Regeneration
Transverse fission
Fragmentation

Question 7

Sexual reproduction

Answer 7

Hermaphroditic
Some internal fertilization
Most have no larval stage

Question 8

Benefits of Endoparasitic cycle

Answer 8

Constant environment
Easy access to food
Protection from predators

Question 9

Costs of endoparasitic cycle

Answer 9

Host is a small and discontinuous habitat
Must be able to overcome hosts defenses
Can’t kill host

Question 10

Endoparasitic Adaptations

Answer 10

Structures for penetration and attachment to host
Usually have resistant stage in life cycle
Reduction in unnecessary structures
Tendency toward being hermaphrodite
Enhancement of reproductive capacity
Use of intermediate larval stages on intermediate hosts
Behavioral adaptations