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Flashcards in Zoology Test 2a Deck (39)
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1

What are Platyhelminthes?

- flatworms
- acoelomates

2

acelomates

without a body cavity (coelom)

3

What is in between the epidermis and gastrodermis?

parenchyma

4

How does embryo of Platyhelminthes differ form that of Cnidarians?

- triploblastic rather than diploblastic
- ectoderm, mesoderm and endoderm
- mesoderm gives rise to true muscle tissue, bones, circulatory system and other internal organs

5

symmetry of platyhelminthes

bilaterally symmetrical
- must actively search for food and mates
- body flattened dorso-ventrally
- cephalization

6

anterior

front

7

posterior

back

8

dorsal

back

9

ventral

front

10

cephalization

- possess head where central nervous system and sensory organs are located

11

digestive system in platyhelminthes

incomplete digestive system
- mouth but no anus
- some of these worms don't have a mouth and absorb nutrients through their specialized skin
- tegument with microtrix to enlarge surface area for absorption

12

excretion and respiration in platyhelminthes

- simple diffusion
- flattened body aides in process, easier for diffusion to occur

13

Platyhelminthes

- Turbellaria
- Monogenea
- Trematoda
- Cestoda

14

types of turbellaria

- free living flatworms
- dugesia (planaria)

15

types of monogenea

- small ectoparasites

16

types of trematoda

- larger 'flukes'
- endoparasites

17

types of cestoda

- tapeworms

18

Dugesia

- type of turbellaria
- also called planarian
- freshwater, tremendous powers in regeneration

19

digestive system of dugesia

- y-shaped with reversible pharynx for feeding

20

turbellaria reproduction (dugesia)

- asexually by fission (fragmentation)
- sexually via complex organ system (syngamy)
- monoecious

21

characteristics of Monogenea

- ectoparasite
- don't harm host
- attach via a haptor to host
- only sexual reproduction (only produce one adult at a time)

22

characteristics of Trematoda

- parasitic flukes with two or three hosts per life cycle
- snail is always found in life cycle (intermediate host)
- vertebrate is almost always definitive host
- Clonorchis (human liver fluke)
- both asexual and sexual reproduction

23

parasites

- loss of sensory structures
- loss of organ systems
- increased reproductive ability

24

definitive host

where parasite has sexual reproduction

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intermediate host

parasite has asexual reproduction

26

characteristics of cestoda

- includes tapeworms
- are endoparasites of vertebrate digestive system with highly specialized anatomy
- anatomy consists of series of proglottids and a 'head' bearing a scolex
- monoecious

27

types of cestoda

- Taenia (beef tapeworm)
-

28

scolex

hooks or suckers

29

What is found inside a proglottid?

- reproductive organs (both male and female)
- nerve cords
- flame cells for excretion, excretory ducts, muscles and parenchyma

30

characteristics of platyhelminthes nervous system

- have up to five pairs of nerve cords
- freshwater flatworms, there is a ladder-type = one pair of lateral nerve cords connected to cerebral ganglia