Unit III: Early branching Metazoa

Question 1

Ctenophora (comb jellies)

Answer 1

• Move via eight “combs” of cilia
• Capture food with sticky colloblast cells
• Decentralized nerve net
• Inner and outer tissue separated by jelly-like mesoglea
• Rotational symmetry

Question 2

combs

Answer 2

groups of cilia Ctenophore use for swimming

Question 3

colloblasts

Answer 3

Ctenophore cells that are sticky and adhere to prey

Question 4

mesoglea

Answer 4

a middle layer of jelly-like material in ctenophora and cnidaria

Question 5

How did Ctenophora develop?

Answer 5

• Embryos for most species are diploblasts
• Two types of germ layer tissues (Exo & Endo)

Question 6

diploblasts

Answer 6

animals that have a nonliving middle layer between the endoderm and ectoderm

Question 7

What are the defining traits of Ctenophora?

Answer 7

• “combs” of cilia
• Colloblasts
• Diploblastic
• Rotational symmetry
• Diffuse nerve net

Question 8

Porifera (sponges)

Answer 8

• Larval stages swim, but adults are primarily sessile
• Lack germ layers, complex tissue, nerve cells, and muscle
• Have 2 different cell types

Question 9

sessile

Answer 9

live permanently attached to substrate

Question 10

What are the 2 cell types of Porifera?

Answer 10

1. Choanocyte
2. Pinacocyte

Question 11

Choanocyte

Answer 11

functions to generate a water current and to trap and ingest food particles via phagocytosis

Question 12

Pinacocyte

Answer 12

epithelial-like cell that forms the outermost layer and encloses a jelly-like substance called mesohyl

Question 13

How was Porifera support achieved?

Answer 13

• Secreted exoskeleton (made of calcium carbonate)
• Spicules
• Spongin fibers

Question 14

Spicules

Answer 14

small bone-like structures that support sponges, made of silica or calcium carbonate

Question 15

Spongin

Answer 15

a modified type of collagen protein that forms the fibrous substance, also supports sponges

Question 16

What are defining traits of Porifera?

Answer 16

• Choanocytes, pinacocytes
• Spicules, spongen

Question 17

Cnidaria

Answer 17

Variety of mostly marine species :
- anemones
- corals
- hydrozoans
- jellyfish
- box jellies

Question 18

Cnidocytes

Answer 18

Specialized stinging cell found in Cnidaria
– usually on tentacles or near cavity opening

Question 19

Nematocyst

Answer 19

harpoon-like organelle within cnidocyte with pointed projectile and poison to stun and entangle prey

Question 20

How do Cnidaria develop?

Answer 20

• Diploblast embryos
• Ectoderm and endoderm layers surround jelly-like mesoglea
• Single gastrovascular cavity with one opening

Question 21

What are defining traits of Cnidaria?

Answer 21

• Cnidocytes and nematocyst
• Diplobastly
• Mesoglea
• Radial symmetry
• Diffuse nerve net

Question 22

What is Cnidaria body plan?

Answer 22

2 main body plan with radial symmetry: Polyp & Medusa
- Some species have life cycle with both forms

Question 23

Polyp

Answer 23

stalk-like sessile life form with mouth and tentacles facing upward, usually sessile but may be able to glide along surface

Question 24

Medusa

Answer 24

free-floating body plan with mouth on underside and tentacles hanging down from a bell