Topic 21: Porifera and Cnidaria

Question 1

Phylum Porifera

Answer 1

basal animals that lack true tissues are informally known as sponges.

Question 2

Except for a motile larval stage, sponges are _____

Answer 2

sessile

Question 3

do sponges have true tissues

Answer 3

no

Question 4

Spicules

Answer 4

provide structural support to sponges (hard needles or rods of silica or calcium carbonate that maintain shape and structure of the sponge)

Question 5

spongin

Answer 5

Some sponges have only a fibrous collagen-protein network for support

Question 6

four simple sponge cell types

Answer 6

Porocytes, Choanocytes, Epidermal cells, amoebocytes

Question 7

Epidermal cells

Answer 7

the outer layer consists of tightly packed epidermal

cells.

Question 8

Porocytes

Answer 8

tubular cells that make up the pores of a sponge

Question 9

Choanocytes (collar cells)

Answer 9

line the spongocoel. They generate a water current through the sponge and ingest suspended food. Bring
oxygen and nutrients to the sponge while also removing waste and carbon dioxide

Question 10

amoebocytes

Answer 10

Mobile amoebocytes are found in the mesohyl where they transport nutrients to other cells of the sponge body, produce materials for skeletal fibres (spicules), or differentiate into other cell types as needed

Question 11

mesohyl (“middle matter”)

Answer 11

The body of a sponge consists of two layers of cells (epidermis and the choanocyte layer) separated by a gel-like, non-cellular matrix, the mesohyl (“middle matter”) that helps maintain the shape and structure of the sponge. Mesohyl contains mobile amebocytes
and skeletal elements (spicules or spongin) deposited by the amebocytes

Question 12

Sponges are _____ feeders

Answer 12

suspension (capturing food particles suspended in water passing through their body)

Question 13

Water is drawn (by beating of choanocyte flagella) through ______ into a cavity called ____ and out through an ____

Answer 13

pores (ostia)
spongocoel
opening (osculum)

Question 14

do sponges have gonads?

Answer 14

no

Question 15

are sponges hermaphrodites?

Answer 15

yes

Question 16

Zygotes retained until they develop into ______

Answer 16

motile ciliated larvae

Question 17

Sponges also reproduce asexually by

Answer 17

fragmentation and by budding.

Question 18

Eumetazoa.

Answer 18

all animals but sponges (animals with true tissues)

Question 19

basal Eumetazoa are two phyla:

Answer 19

Ctenophora and Cnidaria

Question 20

Phylum Cnidaria

Answer 20

• one of the oldest descendants of clade Eumetazoa.

Question 21

Cnidaria body plan

Answer 21

• a simple diploblastic, radial body plan

- The basic body plan of cnidarians is a sac with a central digestive compartment, the gastrovascular cavity

Question 22

Cnidarian body plan two variations

Answer 22

polyp (sessile form) and medusa (motile jellyfish)

Question 23

How do cnidarians feed

Answer 23

predators that use tentacles to capture prey and are armed with cnidocytes

Question 24

cnidocytes

Answer 24

explosive cells that function in defense and capture of prey and contain nematocysts

Question 25

nematocysts

Answer 25

Cnidocytes contain complex secretory organelles called nematocysts that can deliver a sting to other organisms

Question 26

Two major clades of cnidaria

Answer 26

Clade Medusozoa and anthozoa (polyps)

Question 27

Clade Medusozoa are also called

Answer 27

Hydrozoans

Question 28

Hydrozoans

Answer 28

alternate between polyp and medusa forms

Question 29

Clade Medusozoa

Answer 29

the predominant stage in the life cycle of most

scyphozoans (“true jellyfish”) and cubozoans (box jellyfish).

Question 30

Clade Anthozoa

Answer 30

includes the corals and sea anemones and occur only as polyps