Zoology Test 2c Flashcards Preview

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Flashcards in Zoology Test 2c Deck (31):
1

annelids are....

segmented worms

2

characteristics of annelids body form

- eucolomates
- possess a eucoelom or true body cavity
- lined with peritoneum of mesodermal origin
- peritoneum encloses internal organs

3

advantages of true body cavity

- allows for segmentation of body
- individual segments can move independently of each other, master burrowers

4

peristalsis

contraction of muscles for movement of food

5

mesentary

contains blood vessels, hold things in the right place

6

what do nematodes and annelids have in common?

- have bilateral symmetry and cephalization (only internal)
- complete mouth to anus digestive tract
- parasitism occurs in both groups, but annelids are mostly ectoparasites
- no developed respiratory system
- require wet or moist environment

7

nematode muscles

muscular pharynx, but no muscles in intestine, contain longitudinal muscles

8

annelid muscles

contain both circular and longitudinal muscles in body walls and digestive system

9

nematode excretory system

use diffusion through excretory canals

10

annelid excretory system

- more complex
- basic unit is the nephridium
-nephridium covered in chlorogogue cells

11

homoplasy

similarity probably due to convergent evolution

12

homology

anatomy similar due to evolutionary derivation from common ancestor

13

chlorogogue cells in annelids

- cells that cover the peritoneum of the digestive system
- convert waste product of protein metabolism to ammonia and urea
- synthesize glycogen and fat from excess calories

14

nematode circulatory system

contains no circulatory system

15

annelid circulatory system

complex, closed circulatory system of arteries, capillaries and veins
- have multiple hearts (aortic arches)
- aortic arches regulate blood pressure
- pumping done by muscular dorsal vessel
- respiratory pigments present

16

nematode respiratory system

- no specialized structures to increase efficiency of gas exchange
- done via diffusion

17

annelid respiratory system

- some contain "gills" or structures containing blood
- but most non- marine forms have no specialized structures and breath via diffusion

18

nematode nervous system

dorsal and ventral nerve cords

19

annelid nervous system

- have ventral nerve cord connected to dorsally located brain via circumpharyngeal connectives
- each segment has pair of nerves

20

somite

means segment

21

annelid classes

- oligochaeta
- polychaeta
- hirudinea

22

oligochaeta

- mainly earthworms, have few setae
- Lumbricus terrestris

23

setae

means bristles

24

polychaeta

- mainly marine annelids, many setae
- Nereis virens

25

hirudinea

- leeches

26

characteristics of Lumbricus terrestris

- type of oligochaeta
- soil and freshwater annelid
- with few and small setae
- common earthworm
- complete digestive system (mouth to pharynx to esophagus to crop to gizzard to gut)
- monoecious, but don't self fertilize
- detrivores, important to recycling nutrients

27

characteristics of Nereis virens

- type of polychaeta
- marine annelids
- external cephalization
- known as tube worms
- contain parapodia
- many setae
- dioecious, no permanent organs
- indirect development, contains a larvae stage

28

parapodia

fleshy extensions of each somite

29

characteristics of leeches

- type of hirudinea
- freshwater predator of invertebrates
- ectoparasite of vertebrates
- segmented but no setae
- anterior and posterior suckers
- monoecious with direct development
- 4 to 12 pairs of testes and pair of ovaries

30

how do leeches differ from annelids?

- setae are lacking
- no septa are present, but do have external segmentation
- coelom is filled with connective or chlorogogue tissue
- modified circulatory system, closed
- digestive system is modified for fluid feeding

31

septa

internal segmentation