Lophotrochozoans

Question 1

Characteristics of bilaterians?

Answer 1

• bilateral symmetry, triploblastic
• muscle tissues + organs from mesoderm
• protostomes and deuterostomes
• possess coelom and complete digestive tract
• differentiated along posterior-anterior axis

Question 2

Features of differentiation in bilaterians?

Answer 2

• cephalization (sensory structures concentrated at anterior)
• directional motility
• concentration of neural ganglia
• reproductive + digestive structures discahrge posteriorly
• regulated by Hox genes

Question 3

What is phylum acoela?

Answer 3

Basal to the 3 bilaterian clades, these marine worms are simple scavengers.

Question 4

What are the 5 phylum in Lophotrochozoa?

Answer 4

Platyhelminthes, Ectoprocta, Brachiopoda, Mollusca, Annelida

Question 5

Features of Platyhelminthes?

Answer 5

• flatworms that live in moist areas or water
• triboplastic but no coelom
• mouth and gut cavity but no anus
• no circulatory or gas exchange system (diffusion due to flat body shape)

Question 6

Characteristics of free-living Rhabditophora?

Answer 6

• prey on small organisms in freshwater
• anterior cephalization with eye spots
• centralized nerve net
• gastrovascular cavity with one opening
• hermaphrodites, sexual/asexual

Question 7

Characteristics of parasitic Rhabtidophores? What are the two types?

Answer 7

• suckers or hooks for host attachment
• tough, outer covering
• definitive host where it sexually reproduces
  Trematodes, Tapeworms

Question 8

What are tapeworms?

Answer 8

• endoparasitic in digestive system of animals, absorb nutrients from hosts intestines
• long chain of proglottids containing sex organs
• hermaphrodites

Question 9

Tapeworm lifecycle?

Answer 9

• fertilized eggs consumed by host 1
• larvae encyst in tissues of host 1
• host 1 eaten by host 2
• Larvae develop into tapeworms in gut of host 2, sexual reproduction occurs
• fertilized eggs eit body via feces

Question 10

What are Catenulida?

Answer 10

low diversity flatworms, free-living, reproduce via budding

Question 11

What are the 2 lophophorates and features of lophophorates?

Answer 11

Ectoprocta, Brachiopoda
- lophophore - feeding structure with a fan of ciliated tentacles around the mouth
- sessile, aquatic, coelomates
- planktonic larval stage

Question 12

Characteristics of Ectoprocta?

Answer 12

• sessile colonial animals resembling coral
• form colonies in calcium carbonate skeleton
• hermaphrodites and budding
• suspension feeders using retractable lophophore
• U-shaped gut, anal opening outside lophophore

Question 13

Characteristics of Brachipoda?

Answer 13

• resemble molluscs
• attached to sea floor by a stalk
• suspension feeders using paired lophophores
• complete gut (anus optional)

Question 14

What are the 2 trochozoans and features of trochozoans?

Answer 14

Mollusca and Annelida
- motile trochophore larvae
- planktonic larvae with 2 cilia bands that facilitate movement and guide food to mouth
- sensory plate with eye spot above cilia bands

Question 15

Body plan of Mollusca?

Answer 15

1) Muscular ventral foot used for locomotion
2) Visceral mass above foot with internal organs
- reduced coelom, hemocoel
3) Mantle secretes shell
- involved in respiration and secretion

Question 16

Segmented? Gills? Feeding? Circulation? Sex? Life cycle?

Answer 16

No
Located in mantle cavity for gas exchange or feeding
Rasp-like radula
Open circulatory system using hemolymph
separate sexes, gonads in visceral mass
ciliated trochophore larval stage

Question 17

Class Polyplachophora features?

Answer 17

chitons: oval-shaped, protective shell with 8 dorsal plates
- use foot as a suction cup to adhere to rocks
- radula scrapes algae

Question 18

Class Gastropoda features?

Answer 18

slugs + snails
- only aquatic have trochophore stage
- may have shell secreted by mantle
- terrestrial lost gills, mantle cavity developed into simple lung
- move using ventral foot or cilia action
- cephalization; antenna, eyes, ganglia, mouth

Question 19

Class bivalvia features?

Answer 19

• shell divided in 2 halves drawn together via adductor muscles
• may have eyes + tentacles at edge of mantle
• suspension feeders using gills in mantle cavity
• no cephalization; no head or radula

Question 20

Class Cephalopoda characteristics?

Answer 20

• no external shell except nautiluses
• may have gas-filled internal shell for buoyancy control
• long tentacles around mouth evolved from foot
• modified radula as a biting beak
• immobilize prey with poisonous saliva
• siphon (fused mantle tube) for jet propulsion
• closed circulatory system supporting active lifestyle
• direct development, no trochophore larvae

Question 21

2 clades of Annelida and features?

Answer 21

Errantia, Sedentaria
- segmented worms with fused rings called annuli
- segments separated by septa
- coelom lined with mesodermally-derived tissues and acts as hydrostatic skeleton
- cephalization; mouth and ganglia
- complete digestive system
- closed circulatory system

Question 22

Features of Errantia?

Answer 22

predatory, mobile with parapodia on each segment
- parapodium has chaetae and chitin bristles
- external gills, free-spawning
- cephalization; sensory antennae and eyes
- external fertilization, hatch into trochophore larvae

Question 23

Features of Sedentaria?

Answer 23

less mobile
- may burrow into substrate and ingest substrate
- may live in tubes; elaborate gill/tentacles for suspension feeding
- no parapodia, reduced cephalization
- may undergo direct development

Question 24

Features of leeches?

Answer 24

• no parapodia or chaetae
• predeators/parasites
• hermaphrodites, reproduce through reciprocal fertilization
• direct development

Question 25

Features of earthworms?

Answer 25

• ingest soil, digest organic matter
• no parapodia, 4 pairs of chaetae/segment
• hermaphrodites, reciprocal fertilization
• direct development