L6 Cnidarians

Question 1

How many body layers in the cnidarians?

Answer 1

2, is diploblastic

Question 2

What is the mesoglea?

Answer 2

Tissue between the two body layers, is connective tissue and acts as a hydrostatic skeleton

Question 3

Do they have organs?

Answer 3

Limited

Question 4

What are the two forms in which they can exist?

Answer 4

Polyp or medusa, are the same, but reversed

Question 5

What are cilary receptors?

Answer 5

For detection in the environment

Question 6

What are interstitial cells?

Answer 6

Can transform into other cells

Question 7

What are neutrons?

Answer 7

Form the nervous system, a nerve net

Question 8

What are enzymatic gland cells?

Answer 8

Discharges enzyme into the gut?

Question 9

What are muscle cells?

Answer 9

Take up products of digestion, where the process of breakdown is completed.

Question 10

How do the nematocysts, stinging cells, function?

Answer 10

Designed to capture and sting the prey, On stimulation, there is a build up of Ca, which causes a change in the osmotic pressure, meaning water floods into the cell, which opens, shooting the barb out - cannot be used, but can be replaced

Question 11

what are glaucus?

Answer 11

A species of sea slug that eats the cnidarians, and can retain the nematocysts, and use them for its own means

Question 12

What mode of feeding do most cnidarians have?

Answer 12

Carnivorous, captured in the tentacles and transferred to the mouth

Question 13

What are the different classes of the cnidarians?

Answer 13

Hydrozoans
Schyphozoans
Cubozoans
Anthozoans

Question 14

How do the hydrozoans live?

Answer 14

Usually are colonial, other than the hydra, sometimes show secondary polymorphism.

Question 15

What is the role of the medusa forms in the Hydrozoa?

Answer 15

Reproducing, is sometimes retained, when no polymorphism. Juvenile is medusa

Question 16

What are planula?

Answer 16

free-swimming, flattened, ciliated, bilaterally symmetric larval form of various cnidarian species

Question 17

What are siphonophores?

Answer 17

Most sophisticated of the hydrozoans, marked as one of the 4 pinnacles of social evolution, for example, Portuguese man of war. Rely on currents for movement, all part shave individual roles, working together as a whole.

Question 18

What are the schyphozoans?

Answer 18

True jellyfish

Question 19

Which stage is dominant in the schyphozoans?

Answer 19

The medusa stage

Question 20

What is the rhopalium?

Answer 20

Formed of two layers of muscle, one I on the surface, they form contractile forces, so it can pulse the umbrella, allowing it to move and swim. Still has to rely on currents

Question 21

What are stantocysts?

Answer 21

Allow the jellyfish to sense gravity

Question 22

What are pigment cup ocelli?

Answer 22

Form of simple eyes that allow the jellyfish to detect light and dark

Question 23

What could happen to jellyfish populations if sea temperatures increase?

Answer 23

Can move into new areas, and cause a boost in populations, boasts a problem for tourism and for other animals

Question 24

What are the cubozoa?

Answer 24

Box jellyfish

Question 25

How do box jellyfish differ from true jellyfish?

Answer 25

Are active swimmer, up to 2m/s, are smaller and highly toxic

Question 26

What do box jellyfish feed on?

Answer 26

Mostly small fish, but can cause human fatalities

Question 27

What are the anthozoa

Answer 27

Sea anemones, corals

Question 28

What form are the anthozoa found in?

Answer 28

In the polyp stage, can be colonial or solitary

Question 29

How do anthozoa reproduce?

Answer 29

Medusa stage is absent, gametes are released into the sea
May be asexual, by pedal laceration
May be sexual, are hermaphrodites, so produce egg and sperm at different times. Fertilisation takes place in the gastrovascular cavity, or in the sea

Question 30

What are the symbiotic relationships seen in anthozoa?

Answer 30

With clown fish, the clown fish lives in the anemone tentacles, doesn’t get stung by nematocysts. Both will benefit from this intereaction
Relationship with zooxanthella, found in reefs

Question 31

What is the skeleton of corals composed of?

Answer 31

Caco3