Porifera + Cnidaria

Question 1

What are porifera and some of their features?

Answer 1

Basal animals without true tissues; sponges
- marine and sessile
- no organs or internal systems

Question 2

How do porifera get structural support?

Answer 2

Spicules - tiny silica or calcium carbonate rods
Spongin - fibrous collagen-protein network

Question 3

What are the 4 cell types of Porifera?

Answer 3

Choanocytes, amoebocytes, porocytes, epidermal cells

Question 4

What cells line the spongocoel and generate water currents by beating their flagella. What else do they do?

Answer 4

Chonaocytes (collar cells).
- capture suspended food particles
- deliver O2 and nutrients and remove CO2 and waste

Question 5

What cells are mobile and found in the mesohy transporting nutrients to other cells. What else do they do?

Answer 5

Amoebocytes.
- produce materials for spicules
- differentiate into other cell types as needed

Question 6

What cells are tubular and make up the pores of a sponge?

Answer 6

Porocytes

Question 7

What cells form the outer layer of tightly packed cells

Answer 7

Epidermal

Question 8

What is the mesohyl and what does it do?

Answer 8

Gel-like non-cellular matrix separating the epidermis and choanocyte layer.
- provides structure and support via skeletal elements deposited by amoebocytes

Question 9

How do sponges feed?

Answer 9

Suspension feeding
- Water is drawn in via flagella through ostia into the spongocoel and out the osculum
- Collar cells extract food particles using microvilli whoch are engulfed via phagocytosis and digested
- Amoebocytes may transfer nutrients to other cells or use them to create structural elements

Question 10

What are the reproductive structures of sponges like?

Answer 10

Hermaphrodites which can’t self-fertilize
- Eggs develop from modified amoebocytes
- zygote develops into motile, ciliated larvae within mesohyl

Question 11

How do sponges reproduce?

Answer 11

Asexually - fragmentation and budding
Sexually
- Eggs produced by modified amoebocytes in mesohyl of ‘female’ sponge
- sperm produced by modified choanocytes in ‘male’ sponge
- sperm released through osculum
- choanocytes of female sponge trap sperm cells which are delivered to eggs via ameobocytes
- internal fertilization and development occurs

Question 12

Sponge lifecycle from larvae?

Answer 12

Larvae develop in water and eventually settle and attach to solid substrate and become sessile

Question 13

How do sponges interact with the environment?

Answer 13

• clean water via suspension feeding
• form symbiotic mutualisms with algae in photic zones
• may be harvested for bath and art
• produce toxic chemicals to avoid predation providing a safe space for small organisms

Question 14

Features of Cnidarians?

Answer 14

• sessile and motile marine organisms
• jellyfish, sea anemones, corals
• radially symmetrical, diploblastic body plans

Question 15

Cnidarians have a sac-like body with a central _____________ _______. They have a single opening which functions as a _____/______.

Answer 15

gastrovascular cavity, mouth/anus

Question 16

What are the layers in a cindarian?

Answer 16

An outer epidermis is derived from the ectoderm.
Inner gastrodermis derived from endoderm and lines gastrovascular cavity.
Separated by mesoglea - middle jelly

Question 17

How do Cindarians capture prey?

Answer 17

stinging tentacle with cnidocytes surround the opening
- cnidocytes have nematocysts which deliver stinging toxins to immobilize prey
- tentacles move immobilized prey to gastrovascular cavity

Question 18

How does gas exchange occur?

Answer 18

Diffusion across epidermis

Question 19

Lifestyle of polyp vs medusa

Answer 19

Sessile polyp attaches to substrate with oral end exposed upwards.
Motile medusa moves freely through the water via a hydrostatic skeleton, oral end downwards

Question 20

What are the 3 types of Medusozoas?

Answer 20

Hydrozoans
Scyphozoans
Cubozoans

Question 21

Hydrozoan lifestyle?

Answer 21

• alternate b/w polyp and medusa forms
• polyp is sessile, reproduces via budding
• medusa are produced via budding but reproduce sexually
• alternate b/w sexual and asexual, both 2n

Question 22

Scyphozoans/Cubozoans lifestyle?

Answer 22

• predominant medusa stage
• use hydrostatic skeleton to move via contraction-pulsation of body
• cubozoans have cnidocytes

Question 23

What are Anthozoans?

Answer 23

• corals and sea anemones
• only polyps, asexual reproduction

Question 24

Coral lifestyle?

Answer 24

• form colonies via budding or fission
• gain nutrition via symbiotic algae
• hard exoskeleton of calcium carbonate
• reef-building organisms