Cnidaria

Question 1

What was the big innovation of the cnidaria?

Answer 1

Cell to cell communication

Question 2

What have the cnidaria lost?

Answer 2

choanocyte

Question 3

Define choanocyte

Answer 3

a flagellated cell with a collar of protoplasm at the base of the flagellum, numbers of which line the internal chambers of sponges.

Question 4

What substance serves as an adhesive between cells?

Answer 4

Collagen

Question 5

What are the septate junctions made from?

Answer 5

connexon

Question 6

Define blastulla

Answer 6

a hollow ball of cells that has punched in such that there is now two layers of membrane

Question 7

What is the opening on the blastulla called

Answer 7

blastopore

Question 8

What kind of symmetry is first observed in this group of cnidarians

Answer 8

biradial symmetry

Question 9

Define operculum

Answer 9

a structure that covers over an arpeture

Question 10

What is the organelle within the cnidocyte cell that fires the cnidocil?

Answer 10

nematocyst

Question 11

What are the three layers in the body wall of the cnidarian polyp

Answer 11

epidermis, mesoglea, gastrodermis

Question 12

The epitheliomuscular cells of polyp contract in which way?

Answer 12

longitudinal

Question 13

What functions as the skeleton of the polyp

Answer 13

The squishy mesoglea

Question 14

In which layer are the nerve cells located in?

Answer 14

epithelio-muscular cells

Question 15

Every cnidarian has this stage, which is larval. What is it?

Answer 15

Planula larva

Question 16

What characteristics define the planula larva

Answer 16

1. starts on substrate
2. has on end that is always forward
3. has to clearly definable layers of cells

Question 17

Define siphonoglyph

Answer 17

a ciliated groove at one or both ends of the mouth of sea anemones and some corals. The siphonoglyph extends into a pharynx and is used to create currents of water into the pharynx. This gave the cnidarians biradial symmetry

Question 18

What is the first of the cnidarians, placed at the bottom of the tree, that first had biradial symmmetry?

Answer 18

anthozoa

Question 19

Where are the gonads found in the anthozoa

Answer 19

In the vascular cavity (gastrodermis)

Question 20

What did the anthozoa have that substituted for a skeleton

Answer 20

It pumps water into its self to stretch back its muscles

Question 21

What is odd about the fact that there is no mesoderm in cnidaria?

Answer 21

they still have retractor muscles

Question 22

What defines cnidarians after the anthozoa

Answer 22

Medusa (free swimming) and dimorphic life cycle (since we now have the medusa)

Question 23

How does the medusa form?

Answer 23

Stroblization. Starting on substrate as polyp-like sturcture, a disk of tissue is made, another one is built on top, this cycle repeats until finally the top disk differentiates into tentacles.

Question 24

How does the medusa digest and expel waste?

Answer 24

It only has mouth, so the food is brought in, guided through different channels and systems that remove nutrients, and then guide the waste back through the mounth.

Question 25

What are the functions of the rhopalium (in scyphozoa)?

Answer 25

Light sensors hidden under flap of mesoglia (so underneath). Are able to orient the organism so that it is always oriented upwards in the water.

Question 26

What small organelles are found in rhopalia (for scyphozoa)

Answer 26

statocysts

Question 27

What innovations are found with the advent of cubozoa?

Answer 27

medusa undergoes metamorphosis into another medusa,
unique eye
pedalia

Question 28

What is the the pedalium?

Answer 28

part of the feeding structure, has the statocyst

Question 29

What did the hydrozoa innovate

Answer 29

medusa from lateral buds
dimorphic life cycle
velum