lecture 2

Question 1

How do sponges, cnidarians, ctenophores and flatworms differ with respect to body symmetry and presence and number of tissue layers?

Answer 1

Sponges:
BS: asymmetrical/ irregular
T: no tissues

Cnidarians and Ctenophores:
BS: Radial symmetry
T: diploblastic

Flatworms:
BS: bilaterial
T: triploplastic

Question 2

How do sponges, cnidarians, ctenophores and flatworms gather food from their environments and how do the methods differ from each other?

Answer 2

Sponges: filter-feeders. The choanocytes capture food particles when they get trapped by their mucus and then they eat via phagocytosis

Cnidarians and ctenophora: Acoelomate. Gastrovascular cavity (incomplete gut).

Cnidarians also use phagocytosis and prey capture using their cnidocyte and nematocyte

Flatworms: Acoelomate. Gastrovascular cavity (incomplete gut)

Question 3

what organs systems are present in free-living flatworms (Turbellaria)?

Answer 3

only a digestive system (incomplete gut)

no circulatory or respiratory system

Question 4

which organ system is absent in tapeworms (Cestoda)?

Answer 4

through evolution lost their mouths and digestive systems and absorb nutrients directly through their body wall

Question 5

what do rotifers have that platyhelminths don’t?

Answer 5

1. complete digestive tract: mouth and an anus. (food only travels in one direction= increased efficiency)
2. pseudocoelomate

Question 6

which major groupings of animals defined on the basis of morphological characters have been confirmed by molecular sequence studies?

Answer 6

. idk

Question 7

Parazoa (no tissues).

what phylum is under here?

Answer 7

Porifera (sponges)

Question 8

another word for openning

Answer 8

osculum

Question 9

Porifera don’t have tissues but they do have 3 different cell layers namely

Answer 9

Layers arrange around spongocoel:

1. Inner layer = choanocyte
2. Mesohyl (with spicules that provide support and amoeboid cells)
3. outer cover= flattened cells of pinacodem

Question 10

Eumetazoans with radial symmetry: Radiata have 2 phyla

Answer 10

1. Cnidaria

2. Ctenophora

Question 11

cnidarian life/ reproductive cycle. They can either be …………..(2)

Answer 11

only polyp or medusa , some switch between both

Question 12

what are the 4 lineages of Cnidaria and are they polyp,medusa or both

Answer 12

1. Hydrozoa: both
2. jellyfish (Scyphozoa) and box jellyfish (Cubozoa): Medusa (release gametes into water where fertilisation takes place)
3. Anthozoa : polyps

Question 13

2 types of Anthozoa

Answer 13

1. corals

2. sea anemones

Question 14

scientific name for flatworms

Answer 14

platyhelminthes

Question 15

4 types of platyhelminthes

Answer 15

1. turbellaria
2. trematoda
3. monogenoid
4. cestoda

Question 16

what type of body symmetry do sponges exhibit

Answer 16

dont exhibit any kind of body symmetry

Question 17

how does the sponge gather food from its environment

Answer 17

gathers food from its environment by drawing water into its body through numerous small pores and harvesting particulate matter from the water with its choanocytes, or collar cells

Question 18

how do cnidarians capture, consume, and digest their prey

Answer 18

capture prey by stinging it with their nematocytes and using their tentacles to pull it into their mouth

Question 19

which group of cnidarians has only a polyp stage in its lifecycle

Answer 19

the anthozoans, including sea anemones and corals

Question 20

what do ctenophores eat, and how do they collect their food

Answer 20

microscopic plankton in sticky filaments on their 2 tentacles, which are then drawn across the mouth

Question 21

what organ systems are present in free-living flatworms (tubellaria) (4)? which of these organ systems is absent in tapeworms (cestoda)(1)

Answer 21

Free living flatworms have digestive, excretory, nervous and reproductive systems.

Tapeworms lack a digestive system