Lecture 17

Question 1

Bilateria 4 characteristics

Answer 1

1. bilateral symmetry
2. varying degrees of cephalization
3. triploblastic embryos
4. protostome or deuterostome development

Question 2

cephalization

Answer 2

differentiation of head region, including anterior

concentration of neural ganglia (brain), frequently reduced in sedentary animals

Question 3

triploblastic

Answer 3

endo, ecto, and mesoderm

Question 4

Phylum Acoela (400)

Answer 4

marine worms, like flatworms are acoelomate, flat, minimal cephalization, ventral mouth, no anus, but no brain nor gut cavity, endocellular digestion instead, some molecular data place at base of bilateria

Question 5

worm

Answer 5

general term for an animal with a body that lacks shells or elaborate appendages and is usually longer than wide

Question 6

Lophotrochozoa

Answer 6

protostomes, lophophore or trochophore larva

Question 7

5 main Lophotrochozoa phyla

Answer 7

1. Platylhelminthes
2. Brachiopoda (300)
3. Ectoprocta (5000)
4. Annelida (16 500)
5. Mollusca (93 000)

Question 8

Phylum Platylhelminthes

Answer 8

flatworms, acoelomate, some have trochophore-like larvae, no circulatory or gas-exchange system, flatness allows most cells to be in contact with water/air, do not have complete digestive system

Question 9

Platylhelminthes 2 Classes

Answer 9

1. Turbellaria

2. Cestoidea

Question 10

Class Turbellaria

Answer 10

free-living flatworms, most marine some freshwater few moist soil, predatory on other small metazoans, some eat bacteria and protists or decaying organic matter, or have symbiotic green algae

Question 11

Turbellaria morphology

Answer 11

1. epidermis covered by cilia
2. pair of ventral nerve cords
3. pair of ganglia near front of body
4. no anal opening

Question 12

Turbellaria reproduction

Answer 12

most are hermaphroditic, transfer sperm by piercing the
body of a partner with sharp copulatory organ, often both desire to transfer sperm, leads to “penis-fencing”, one species able to copulate with its own head

Question 13

Class Cestoidea

Answer 13

tapeworms, endoparasitic in digestive systems of other animals

Question 14

Cestoidea morphology

Answer 14

1. lack digestive system (absorb nutrients through thin body wall)
2. scolex (front end of body) modified for holding on to host’s gut with suckers/hooks
3. after scolex has proglottids

Question 15

proglottids

Answer 15

long chains of units devoted to reproduction in cestoids, new at base of scolex, old toward posterior of body

Question 16

Cestoidea reproduction

Answer 16

1. mature proglottids filled with eggs are
   defecated by host
2. eggs eaten by intermediate host, develop into larvae that encyst in tissues of intermediate host
3. final host eats intermediate host, larvae develop into adult tapeworm in gut of final host

Question 17

final/definitive host

Answer 17

the host in which the parasite engages in sexual reproduction

Question 18

Echinococcus spp.

Answer 18

dog tapeworms, have herbivorous mammals as
intermediate hosts, but occasionally eggs get into
humans

Question 19

Echinococcus in humans

Answer 19

1. eggs hatch in small intestine
2. larvae migrate through circulatory system to liver (sometimes end up in other soft tissues)
3. larvae undergo asexual reproduction, split into thousands of new larvae, all located in a large hydatid cyst
4. can go undetected for up to 20 years, but when cyst becomes big it causes problems

Question 20

Phylum Brachiopoda

Answer 20

lamp-shells, all marine deep-water, much more diverse in the past

Question 21

Brachiopoda morphology

Answer 21

1. lophophore-bearing
2. complete gut with anal opening
3. look like bivalve molluscs
4. some attached to substrate by rubbery stalk

Question 22

Brachiopoda feeding

Answer 22

suspension feed using paired lophophores

Question 23

Phylum Ectoprocta (aka Bryozoa)

Answer 23

most marine few freshwater, gut is U-shaped with anal opening outside of the lophophore, colonial

Question 24

Ectoprocta colonies

Answer 24

stalked colonies or moss-like mats, look like coral, but have units specialized for different tasks and some are able to move

Question 25

Phylum Annelida

Answer 25

segmented worms

Question 26

Annelida 3 classes

Answer 26

1. Polychaeta 2. Oligochaeta (within polychaeta) 3. Hirudinea (within polychaeta)

Question 27

4 Annelid characteristics

Answer 27

1. segmented 2. eucoelomate 3. closed circulatory system 4. complete digestive system with anus

Question 28

segmented

Answer 28

many repeated units with similar internal and external anatomy, separated by internal septa

Question 29

"Polychaeta"

Answer 29

marine

Question 30

polychaeta morphology

Answer 30

1. parapodia | 2. clearly differentiated head with sensory antennae, often eyes

Question 31

parapodia

Answer 31

fleshy lobes that bear many chaetae

Question 32

errant polychaetes

Answer 32

active, parapodia and head better developed than sedentary species

Question 33

sedentary

Answer 33

rarely move, but can if necessary

Question 34

errant polychaete feeding

Answer 34

predatory

Question 35

sedentary polychaete feeding

Answer 35

ingest substrate, suspension feed, or deposit feed

Question 36

deposit feeding

Answer 36

trailing sticky tentacles over substrate and licking off adhering matter

Question 37

polychaete reproduction

Answer 37

1. free spawning 2. some species have modified body parts swim to surface to release gametes 3. trochophore larvae are planktonic 4. subsequent larvae lead benthic lives

Question 38

free spawning

Answer 38

eggs and sperm released into water, fertilization occurs outside body of female parent

Question 39

"Oligochaeta"

Answer 39

earthworms, lack parapodia and well-developed head, non-leech spp. still have a few chaetae, feed by ingesting substrate and digesting organic matter

Question 40

oligochaete reproduction

Answer 40

1. simultaneous hermaphrodites, transfer sperm by copulation (do not free spawn) 2. deposit sperm in partner’s seminal receptacle, receives in own 3. produces gelatinous cocoon with secretions from clitellum 4. deposits eggs in cocoon, slides cocoon forwards, deposits sperm (external fertilization) 5. direct development (no larval stage)

Question 41

composting

Answer 41

terrestrial oligochaetes create smaller fragments of organic matter, and aerate soil through turning over and burrowing

Question 42

de-worming of Canada

Answer 42

caused by glaciation, now crawling back

Question 43

"Hirudinea"

Answer 43

leeches, mostly freshwater, some marine and terrestrial, nested within oligochaetes

Question 44

hirudinea morphology

Answer 44

1. lack parapodia, have clitellum | 2. lack chaetae

Question 45

hirudinea feeding

Answer 45

1. predators of soft-bodied invertebrates or feed on blood of vertebrates 2. blood feeders secrete anaesthetic and anticoagulent, resurging interest in medicinal leeches

Question 46

Phylum Mollusca

Answer 46

snails, clams, squids, and more, mostly marine some freshwater or terrestrial

Question 47

3 main classes Mollusca

Answer 47

1. gastropoda (75%) 2. bivalvia 3. cephalopoda (650)

Question 48

mollusca morphology

Answer 48

1. calcareous shell enclosing soft body (lost or reduced in many) 2. mantle - thin layer secretes calcareous shell 3. muscular ventral foot used for movement, organs contained in visceral mass above 4. radula (straplike rasping organ) for mouthparts 5. gills for gas exchange and sometimes feeding 6. open circulatory system 7. not clearly segmented 8. many with trochophore

Question 49

class gastropoda

Answer 49

snails, most marine many terrestrial and freshwater, trochophore larvae

Question 50

gastropoda morphology

Answer 50

1. glide using muscular contractions of large foot 2. single coiled tubular shell (except slugs) 3. shelled undergo torsion 4. terrestrial snails and slugs use lung instead of gills

Question 51

torsion

Answer 51

visceral mass twists during development so that anal opening over head

Question 52

gastropoda feeding

Answer 52

grazers scrape algae off substrates using radula, few predatory

Question 53

nudibranchs

Answer 53

shell-less marine gastropods ‘sea slugs’, many brilliantly coloured, protected by nematocysts of cnidarians (eat cnidarians, but prevent nematocysts from firing and store nematocysts in own tissues)

Question 54

class bivalvia

Answer 54

clams, oysters, scallops, most marine many freshwater, 2 hinged shells, no radula, feed by filtering water through gills, most sedentary some essentially sessile

Question 55

bivalvia economic importance

Answer 55

many eaten, response in irritant to mantle exploited to make pearls, some are invasive pests

Question 56

class cephalopoda

Answer 56

squids, cuttlefish, octopuses

Question 57

cephalopoda morphology

Answer 57

1. many long tentacles arranged around mouth 2. tentacles have suckers or hooks 3. radula modified as biting beak (predatory) 4. most have no evidence of external shell, cuttlebone of cuttlefish is an internal shell remnant 5. tube of mantle fused to make siphon 6. only molluscs to have closed circulatory system 7. excellent vision, complex behaviour, and intelligent

Question 58

siphon

Answer 58

used for jet-propulsion, particularly by squids

Question 59

cephalopoda reproduction

Answer 59

1. many octopuses show maternal care (protect eggs until young hatch) 2. direct development