Lophophorates

Question 1

What is the function of the brachiopod lophophore?

Answer 1

Feeding and gas exchange.

Question 2

Which brachiopod class is more primitive?

Answer 2

Inarticulata (muscle-held valves, chitinous shell).

Question 3

What is the pedicle in brachiopods?

Answer 3

A stalk that anchors the animal to the substrate.

Question 4

What are the two brachiopod classes?

Answer 4

1) Articulata (tooth-and-socket hinge), 2) Inarticulata (muscle attachment).

Question 5

What distinguishes brachiopod shells from mollusc shells?

Answer 5

Brachiopods have dorsal/ventral valves made of calcite or chitinophosphate; molluscs have lateral aragonite valves.

Question 6

What type of symmetry do bryozoans have?

Answer 6

Bilateral symmetry.

Question 7

What level of organization do bryozoans have?

Answer 7

Organ-system level.

Question 8

What is an ancestrula?

Answer 8

The primary zooid from which a bryozoan colony forms by budding

Question 9

How do bryozoans reproduce?

Answer 9

Colonies are hermaphroditic; individual zooids may be single-sex. Most species brood embryos.

Question 10

What distinguishes Class Stenolaemata?

Answer 10

All marine, tubular erect forms, calcified zooecium, only retractor muscles withdraw the lophophore.

Question 11

What are autozooids and heterozooids?

Answer 11

Autozooids: feeding and reproductive zooids; Heterozooids: specialized non-feeding zooids (e.g., avicularia, vibracula).

Question 12

What are the two orders of Gymnolaemata?

Answer 12

1) Ctenostomata (flexible, chitinous zooecium), 2) Cheilostomata (calcified zooecium, operculum present).

Question 13

What distinguishes Class Gymnolaemata?

Answer 13

Primarily marine, morphologically distinct zooids, circular lophophore, no epistome.

Question 14

What distinguishes Class Phylactolaemata?

Answer 14

Freshwater habitat, monomorphic zooids, thick gelatinous or chitinous covering, U-shaped lophophore with epistome.

Question 15

What are the two types of statoblasts?

Answer 15

Floatoblasts (buoyant) and Sessoblasts (cemented to substrate).

Question 16

What are statoblasts?

Answer 16

Dormant structures produced by Phylactolaemata bryozoans that withstand harsh conditions and aid in asexual reproduction.

Question 17

How do bryozoans respire and circulate materials?

Answer 17

By diffusion; they lack specialized respiratory and circulatory systems.

Question 18

What is the function of funicular cords in bryozoans?

Answer 18

Tissue connections between individual zooids for transport and communication.

Question 19

How does the bryozoan lophophore relate to the coelomic cavity?

Answer 19

Coelomic fluid of the metacoel is continuous with the lophophore and tentacle cavities (mesocoel).

Question 20

What is a brown body in bryozoans?

Answer 20

A degenerated polypide mass that may help survive unfavorable conditions or eliminate waste.

Question 21

What is contained within the bryozoan polypide?

Answer 21

Lophophore, gut, nerve ganglia, and most musculature.

Question 22

What is a zooecium?

Answer 22

The secreted “house” around a bryozoan’s body.

Question 23

Are bryozoans colonial or solitary?

Answer 23

Colonial.

Question 24

What are 3 additional common features of lophophorates besides the lophophore?

Answer 24

1) Simple gonads from mesodermal lining of the metacoel, 2) U-shaped digestive tract with anus near the mouth, 3) Protective covering (tube, shell, exoskeleton).

Question 25

What happens during metamorphosis of the actinotroch larva?

Answer 25

The metasomal sac everts, bringing mouth and anus-bearing regions closer.

Question 26

What larval type is typical of phoronids?

Answer 26

Actinotroch larva.

Question 27

How do phoronids reproduce?

Answer 27

Both asexual (fission, budding) and sexual reproduction; transient gonads; gametes exit via nephridia.

Question 28

How do phoronids perform excretion?

Answer 28

Via a pair of metanephridia in the trunk, each with two nephrostomes, discharging near the anus.

Question 29

What kind of circulatory system do phoronids have?

Answer 29

Extensive system between the lophophore and stomach; no heart; blood contains hemoglobin.

Question 30

Describe the phoronid's lophophore tentacles.

Answer 30

Hollow, ciliated, contain blood vessels and mesocoel extensions; arranged in two rows.

Question 31

How is the phoronid's tube formed?

Answer 31

Secreted by epidermal gland cells; initially sticky to trap sand grains.

Question 32

How do phoronids support their bodies?

Answer 32

Hydrostatic properties of the coelom and weak muscles.

Question 33

What is the epistome in phoronids?

Answer 33

A hollow flap covering the mouth, containing the remnant of the protocoel.

Question 34

Where do phoronids live?

Answer 34

In chitinous tubes in muddy/sandy sediments or attached to surfaces; marine environments from intertidal to 400m deep.

Question 35

How many species and genera are in Phoronida?

Answer 35

About 12 species in two genera: Phoronis and Phoronopsis.

Question 36

What type of body cavity development is common among lophophorates?

Answer 36

Enterocoely with a tripartite body cavity: protocoel, mesocoel, metacoel.

Question 37

Are lophophorates deuterostomes or protostomes based on molecular data?

Answer 37

Molecular data (18S rRNA and mitochondrial DNA) places them with protostomes, specifically the Lophotrochozoa.

Question 38

What are three shared features among all lophophorates besides the lophophore?

Answer 38

Simple gonads from the metacoel U-shaped digestive tract Secretion of a protective covering.

Question 39

What is the mesocoel?

Answer 39

The coelomic cavity within the lophophore, separated from the larger metacoel.

Question 40

How are food particles transported to the mouth in lophophorates?

Answer 40

Lateral cilia move particles to frontal cilia, which pass them along a groove to the mouth.

Question 41

How do lophophorates generate water currents for feeding?

Answer 41

By beating lateral cilia on the tentacles.

Question 42

Where is the coelomic cavity located in the lophophore, and where is the anus?

Answer 42

The lophophore's internal space is a coelomic cavity; the anus lies outside the tentacular ring.

Question 43

What is a lophophore?

Answer 43

A circular or U-shaped ridge around the mouth bearing 1 or 2 rows of ciliated, hollow tentacles.

Question 44

What are the three phyla classified as lophophorates?

Answer 44

Phoronida, Bryozoa, Brachiopoda.

Question 45

What body structure helps phoronids rapidly withdraw into their tubes?

Answer 45

A giant nerve fiber.

Question 46

How does body size relate to lophophore structure in phoronids?

Answer 46

Larger body size correlates with more coiling and more tentacles.