12.2 Annelids & Nematodes

Question 0

Ecdysozoans - main characteristic?

Answer 0

• External covering secreted by epidermis that must be shed in order to grow
• Vulnerable directly after moulting

Question 1

Lophotrochozoans have one of the following characteristics

Answer 1

1. Lophophore (ciliated feeding/gas exchange structure)

2. Trochophore (ciliated free-living larval form)

Question 2

Ecdysozoan - growth?

Answer 2

Happens in steps (although mass increases continuously)

Question 3

2 sub groups of protostome animals?

Answer 3

Lophotrochozoa and ecdysozoa

Question 4

Surname of nematoda?

Answer 4

Roundworms

Question 5

Nematoda are part of which subgroups?

Answer 5

Ecdysozoan (protostomes)

Question 6

Endings of nematoda?

Answer 6

• Tapered posterior end

- Blunt anterior end

Question 7

Roundworms - body?

Answer 7

• Multilayered, flexible cuticle
• Pseudocoelomates
• Longitudinal muscles

Question 8

Nematoda - use of cuticle?

Answer 8

Allows diffusion of gases (must live in moist habitat)

Question 9

Nematoda - body cavity?

Answer 9

• Fluid filled (hydrostatic skeleton)
• Complete digestive tract
• No respiratory or circulatory system

Question 10

Nematoda - mode of living?

Answer 10

Free-living (scavengers, predatory) or parasitic

Question 11

Nematoda animal model for geneticists, developmental biologists and neurobiologists? - At McGill: genes in nematodes to live 6x their normal life span

Answer 11

C. elegans

Question 12

Parasitic nematodes infect….

Answer 12

Protists, plants and animals (including humans)

Question 13

Real name of earthworms?

Answer 13

Annelida (segmented worms)

Question 14

Annelida are part of the ….subgroup?

Answer 14

Lophotrochozoans (Protostomes)

Question 15

Annelida - body shape?

Answer 15

Coelomates

Question 16

What are the advantages of segmentation?

Answer 16

• Multiple copies of organs and structures
• Efficient nervous control (because ganglion in each segment, faster response)
• Increases body size

Question 17

What is regional differentiation?

Answer 17

Segments are similar but each can be modified (eg. gut)

Question 18

Explain the locomotion of earthworms?

Answer 18

• Circular muscles contract: anterior end elongates, coelomic fluid is trapped in each segment, posterior setae anchor
• Longitudinal muscles contract: posterior end brought forward, posterior setae release

Question 19

Systems present in annelids?

Answer 19

• Respiratory (through epidermis)
• Nervous (anterior “brain”, ventral nerve cord, segmental ganglia)
• Circulatory system (closed, dorsal + ventral blood vessels, aortic arches = hearts)

Question 20

Advantages of circulatory system?

Answer 20

• Improved exchange between deeper tissues and surface (O2, CO2), and gut and muscles (nutrients)
• Permits development of a thicker body

Question 21

Predominant groups of annelids?

Answer 21

1. Polychaeta

2. Clitellata (Oligochaeta + Hirudinea)

Question 22

Polychaeta - habitat + feeding mode?

Answer 22

Habitat: marine
Feeding: detritivores, filter-feeders (live in tubes)

Question 23

Polychaeta have many…

Answer 23

Setae (name)

Question 24

Polychaeta - locomotion + respiration?

Answer 24

Parapodia

Question 25

Polychaeta are …….. larvae

Answer 25

Trochophore

Question 26

Oligochaeta - habitat + feeding

Answer 26

Mainly terrestrial

Detritivores - they aerate the soil

Question 27

Oligochaeta have few….

Answer 27

Setae

Question 28

Oligochaeta - Clitellum?

Answer 28

Secretes a mucus cocoon for embryo development

Question 29

Oligochaeta - reproduction?

Answer 29

Hermaphroditic

- No specialized larval stage

Question 30

Hirudinea - habitat + feeding?

Answer 30

Freshwater

Parasitic + Carnivorous

Question 31

Hirudinea - setae?

Answer 31

None. Anterior and posterior suckers

Question 32

Hirudinea - reproduction?

Answer 32

Hermaphroditic - clitellum, no specialized larval stage

Question 33

Hirudinea - uses?

Answer 33

Medicinal - hirudin

Question 34

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Answer 34

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