Phylum Platyhelminthes

Question 0

Unique things about them

Answer 0

• Cestoda have proglottoids and scolex
• combine characteristics (ex. Flame cells + acoelomate)
• larva of each class are unique

Question 1

Characteristics

Answer 1

• eumetazoa: true tissues
• bilateral symmetry
• triploblastic
• acoelomate: true mesoderm

Question 2

Movement

Answer 2

• ciliates
• nervous system controls muscles
• ventral ladder like nervous system

Question 3

Respiration

Answer 3

Diffusion

Question 4

Feeding in free living species

Answer 4

• carnivores
• gastrovascular cavity w/single opening
• pharynx extends and pumps food in
• gut absorbs and digests

Question 5

Feeding in parasitic species

Answer 5

• simple digestive tract; food is obtained from host

- no gut; nutrients/waste diffused through skin

Question 6

Reproduction in free living species

Answer 6

• most are hermaphrodites
• exchange sperm during mating for increased variation
• can asexually reproduce by fission

Question 7

Reproduction in parasitic species

Answer 7

• complex life cycles involving asexual and sexual repro inside multiple hosts

Question 8

Internal circulation

Answer 8

• diffusion

- no gills, respiratory organs, heart, blood, etc

Question 9

Excretion

Answer 9

• O2/CO2 exchanged by diffusion

- some have flame cells

Question 10

Flame cells

Answer 10

• filter and remove excess water and wastes (ex urea, ammonia)
• flame cells join together to form network of tubes that empty externally via pores in skin

Question 11

Response to environment

Answer 11

• more developed sensory systems than Porifera and Cnidaria
• head has ganglia (groups of neutrons), but not complex enough to be a brain
• eyespots detect light or dark (but aren’t true eyes)
• sensory nerves detect changes in enviro. (Ex chemicals or pressure)
• parasitic worms have less developed senses cuz they don’t need to be able to detect light cuz they are inside an organisms body

Question 12

Class Turbellaria

Answer 12

• aka planaria
• free living
• ciliates
• have special secreting cells called RABDITES

Question 13

Class Trematoda

Answer 13

• aka flukes
• parasites
• no cilia
• mostly hermaphrodites
• unique larva stages
• 2 suckers (oral/mouth & ventral) to attach to host
• pharynx leads to blind ending gut that is highly divided to increase surface area

Question 14

Class Cestoda

Answer 14

• parasitic
• no mouth or digestive tract
• absorb pre-digested food through body wall
• scolex/head has hooks & suckers for attachment
• shed mature reproductive units containing eggs called proglottoids

Question 15

Fun facts about tapeworms

Answer 15

• people get tapeworms by eating raw or undercooked meat
• larvae attaches to bowel and develops into adult in 5-12 weeks
• several hundred segments/proglottoids liberate eggs as they mature
  
  • new segments are tiny, so head is tiny. Other segments get bigger as they fill with eggs and then break off