10. Cnidaria

Question 1

Spherical Symmetry

Answer 1

Any plane passing through the center divides the body into mirrored halves
- Floating and rolling

Question 2

Radial Symmetry

Answer 2

Body divided into similar halves by more then two planes passing through the longitudinal axis

• Can interact with environment in all directions
• Sponges, Jellyfish, SeaUrchins
• Sessile, Free Floating or weakly swimming animals

Question 3

Biradial Symmetry

Answer 3

Variant of radial

• Radial symmetry with an aspect of bilateral symmetry
• Comb Jellies(ctenophora) tentacles

Question 4

Bilateral symmetry

Answer 4

Divided along sagittal plane into two mirror portions forming right and left halves

• Much better for directional movement
• Associated with cephalization
• Mouth at front allows efficient feeding

Question 5

Cephalization

Answer 5

The differentiation of the head region and the concentration of nervous tissues and sense organs in the front area

Question 6

Frontal plane

Answer 6

Coronal Plane

- Divides body into dorsal and ventral halves

Question 7

Sagittal Plane

Answer 7

Divides body into left and right

Question 8

Transverse plane

Answer 8

Cross section

- Divides body into anterior and posterior halves

Question 9

Anterior

Answer 9

Head end

Question 10

Posterior

Answer 10

Tail end

Question 11

Dorsal

Answer 11

Back side

Question 12

Ventral

Answer 12

Belly side

Question 13

Medial

Answer 13

Midline of body

Question 14

Lateral

Answer 14

Left and right sies

Question 15

Distal

Answer 15

Parts farther from the middle of the body

Question 16

Proximal

Answer 16

Parts nearer from the middle of the body

Question 17

Cnidaria & Ctenophora similarity

Answer 17

• Radial / Bilateral symmetry
• Cell-tissue level organization
• Diploblastic
• Blind gut

Question 18

Cnidaria

Answer 18

• Mostly sessile or slow moving
• Efficient predetors
• Algae are frequent mutualists
• Mostly marine, some fresh water
• Abundant in shallow marine habitat

Question 19

Two morphological types of Cnidarians

Answer 19

Polyp - Sedentary or sessile

Medusa - Floating or free-swimming

Question 20

Sessile

Answer 20

Fixed in one place

Question 21

Sedentary

Answer 21

Little movement

Question 22

Substratum

Answer 22

Solid surface

Question 23

Polyp form of Cnidarian

Answer 23

• Tube shape
• Sedentary or Sessile
• Mouth surrounded by tentacles
• Can be attached to substratum by pedal disc

Question 24

Medusa form of Cnidarian

Answer 24

• Umbrella - Shaped
• Floating or free swimming
• Mouth centered on concave side
• Tentacles extend from rim of umbrella shape

Question 25

Commonality of Cnidarian forms

Answer 25

- Diploblastic - mesoglea between two tissue layers - Mesoglea is thicker in the medusa form - buoyancy

Question 26

Cnidarian Respiration

Answer 26

Diffusion

Question 27

Cnidarian Digestion

Answer 27

- Mouth opens into gastrovascular cavity - Blind gut - Extra & Intracellular digestion - Undigested material carried back into the cavity by amoeboid cells

Question 28

Cnidarian Reproduction

Answer 28

- Planula Larva - Planula settles and metamorphoses into a polyp - Polyp reproduces sexually or asexually - Colonies form when polyps reproduce asexually but stay attached - Polyps within colony specialize for certain functions - Medusae reproduce sexually

Question 29

Locomotion

Answer 29

- Some polyps are sessile - Hydra and sea anemones can move slowly by gliding on pedal disc - Sea anemones occasionally swim

Question 30

Cnidocyte

Answer 30

Cell that holds cnida

Question 31

Cnida

Answer 31

Stinging organelle - Nematocyst - Most common type of cnida - Many nematocyst have a toxin which paralyzes prey

Question 32

Cnidocil

Answer 32

Triggers the nematocyst to fire

Question 33

Hydrozoa

Answer 33

Typically asexual polyp and sexual medusa - Hydra has only polyp - Others only have medusa

Question 34

Scyphozoa

Answer 34

True jellyfish - Dioecious - Internal fertilization - Medusa and polyp during life cycle

Question 35

Life cycle of Aurelia

Answer 35

1. Sperm Fertilizes egg in Gastric Pouch 2. Zygote develops on arms of female 3. Planula larva attaches and becomes a scyphistoma (Polyp form) 4. Scyphistoma can bud to form other polyps (asexual reproduction) 5. Become a strobila 6. Releases saucerlike buds called ephyrae 7. Ephyrae grow into mature jellyfish (mature form)

Question 36

Cubozoa

Answer 36

"box jellyfish" - Medusa is prominent form - polyp is often uncharacterized - Medusa bells are almost square - Tentacles occur at corners of square - Strong swimmers and predators - String from some species can be fatal to humans

Question 37

Anthozoa

Answer 37

- Polyps with a flower-like appearance: sea anemones, corals, sea fans - No medusa stage - Sexual and asexual reproduction occur in polyp phase - All marine - Solitary or colonial

Question 38

Ctenophora

Answer 38

- Biradial symmetry - All marine, especially in wam waters - Commonly called "Sea walnuts" or "Comb Jellies" - No nematocysts except Haeckelia rubra

Question 39

Symbiosis of Clownfish & Cnidarians

Answer 39

Obligate mutualism - Clownfish cannot survive without anemones Facultative mutualism - Anemones can survive without clownfish

Question 40

Anemone & Clownfish Benefits

Answer 40

``` Benefit to clownfish - Protection - Hide from predators in the tentacles Benefit to Anemone - Clownfish chases other fish and protect anemone from being eaten - Nitrogen supply through ammonia - Water circulation increased ```

Question 41

Crab-Cnidarian symbiosis

Answer 41

Crabs have anemones on claws - genus Lybia | - Steal anemone if missing and tear in half - inducing asexual reproduction

Question 42

Symbiosis with Zooxanthellae

Answer 42

Coral reefs get their colors from mutualistic zooxanthellae algae - Energy from the photosynthetic leftovers Coral bleaching is caused by the death of Zooxanthellae algae