planeria and flatworm

Question 1

Platyhelminthes Characteristics

Answer 1

• Bilateral Symmetry: head and tail region
• move with a sense of direction
• primitive hunters

Question 2

Platyhelminthes are

Answer 2

• triploblastic: ectoderm, endoderm, and mesoderm which builds the muscular, excretory, and reproductive systems.
• acoelomates: no body cavity. body filled systems with cells.

Question 3

Platyhelminthes: true organs

Answer 3

• rudimentary digestion and excretory system
• flattened dorsal-ventrally
• cephalization (concentration of sensory structures and nerves at the anterior end)

Question 4

look at diagram of planarian

Answer 4

• eyespots
• pharynx
• ventral surface
• dorsal surface

Question 5

Flatworm Circulatory/Respiratory system

Answer 5

• no true circulatory or respiratory system
• respire by diffusion (shape maximizes surface area)
• gasses diffuse directly across moist outer surface

Question 6

Digestive System of Flatworm:

Answer 6

• free living Platyhelminthes
• Blind digestive tract: only one opening (no anus)
• Parasitic Platyhelminthes
• Feed on tissues and fluids form host
• Have suckers or hooks to attach to host

Question 7

Flatworm Excretory System

Answer 7

• Removes metabolic wastes
• movement of ciliated cells (flame cells) draws cellular waste away from body cells into tubes leading to external pores

Question 8

Flatworm Nervous System

Answer 8

• centralized nervous systems: brain+nerve cords
• two cord like nerves that run along the ventral side of the body
• can detect differences in light
• some have light sensitive organs called ocelli
• detects chemicals gradients (auricles) (chemoreception)
• enables them to move towards food

Question 9

Flatworm reproduction system

Answer 9

• Hermaphroditic: contains both male and female reproductive organs
• Sperm are shed into environment
• Sperm are taken in through a genital pore where ova are fertilized

Question 10

there are 3 classes of Platyhelminthes

Answer 10

1. class Turbellaria (planaria)
   - free living
   - marine and freshwater
   - nervous system
2. Class Trematoda (parasitic flukes)
   - Obligate parasites
   - life cycle requires 1-3 hosts
   - host usually starts as mollusk then then vertebrate
3. Class parasite: Endoparasitic (tapeworms)

Question 11

Tapeworms

Answer 11

• anterior end is a scolex (head)
• lack a brain
• body segments called proglottids (detach from worms carrying fertilized eggs)
• Hermaphroditic: cross fertilize between worms or self fertilize
• no digestive system
• absorbs nutrients through skin
• release waste into surrounding
• requires 1-3 hosts
• reach up to 10-20m

Question 12

Look at tapeworm diagram life cycle

Answer 12

aye

Question 13

The Coelomate

Answer 13

• Coelom: muscle lined body cavity

- chamber for heart and blood vessels complex digestive systems, excretory organs, and organs for gas exchange

Question 14

Phylum Annelida has how many species

Answer 14

15, 000

Question 15

Annelids have

Answer 15

• segmented bodies allow for potential specialization.

- Sections containing one or more of a series of repeating anatomical features

Question 16

3 classes of Phylum ANNELIDA Segmented Worms

Answer 16

1. Class Oligochaeta (earth worms)
2. Class Polychaeta (tubeworms)
3. Class Hirudinea (leeches)

Question 17

look at earthworms diagram cycle

Answer 17

look

Question 18

Class Oligochaeta Movement

Answer 18

• Longitudinal and circular muscles line digestive tube and inside of cuticle (coelom) allowing for:
• Movement without affecting digestion
• Ability to move food along digestive tract while stationary

Question 19

Digestive system of earthworms

Answer 19

-The earthworm eats soil which contains dead plant matter
-Pharynx: muscular enlargement contributing to swallowing of detritus
-Esophagus: peristalsis moves material to crop
-Crop: storage area for material until gizzard has room
-Gizzard: muscular walls and coarse textured interior
• specialized grinding organ
-Intestine: digestive glands secrete enzymes
• Nutrients absorbed along its length

Question 20

Earthworms Circulatory System

Answer 20

• Closed system: heart and blood vessels
• two major blood vessels (ventral, dorsal)
• Branch into tissues of digestive tract and cuticle
• Runs anteriorly in dorsal/posteriorly in ventral
• Thickened muscular blood vessels act as a heart
• Contract to maintain blood flow

Question 21

Earthworms Respiration System

Answer 21

• Has no respiratory organ.
• It takes in oxygen directly through its skin and gives off carbon dioxide.
• Its skin secretes mucus to prevent dehydration and suffocation

Question 22

Earthworm excretory system

Answer 22

• Nephridia: open-ended tubules collect liquid wastes materials
• Excreted through pores in cuticle
• A pair of nephridia are found in each segment of the worm

Question 23

Earthworm nervous system

Answer 23

Paired ventral nerve cord runs length of worm

• Branches run into tissues of each segment
• Small, bi-lobed brain found on anterior side of pharynx

Question 24

Reproduction Earthworm System

Answer 24

-Hermaphroditic with testes and ovaries as well as sperm
receptacles and yolk sacs
-During mating, worms line up with ventral sides together
-Clitellum secretes slime to aid sperm transfer
• Sperm receptacles: store sperm
-Ova is released encased in yolk from yolk sac and sperm retained
in receptacles
-Fertilization occurs outside worm in another slime cocoon secreted by clitellum
-Trocophore: Larva develops from zygote, and grows into worms
-Larva resembles larva of mollusks, suggesting evolutionary link

Question 25

Class Hirudinea (leech)

Answer 25

-free living predators/ectoparasites
-no significant nervous, digestive, excretory, respiratory or
circulatory systems
-salivary secretion “hirudin” is an anticoagulant and anaesthetic
-anterior + posterior suckers – feeding and attachment

Question 26

Polychaeta (marine segmented worms)

Answer 26

-Parapods: lateral extensions from each segment
-Setae (bristles) mounted on extensions provide increased
abilities for movement
-Distinct cephalization with complex sense organs = predator
-Range from sessile, filter-feeding tube worms to motile,
hunting sandworm