Cnidaria

Question 1

Cnidaria are part of what domain?

Answer 1

Eumetazoa

Question 2

what are the unique features?

Answer 2

cellular differentiation is elaborate with the formation of muscle cells, nerve cells and sensory cells

Question 3

defining characteristic of Cnidarians?

Answer 3

1. secretion of complex intracellular organelles called cnidae (nematocysts)
2. planula larva in the life cycle

Question 4

how many species of Cnidaria?

Answer 4

10,000 species (only some FW, all marine

Question 5

What is their reproductive process?

Answer 5

forming colonies by asexual reproduction

Question 6

define dimorphic?

Answer 6

two different adult morphologies during lifecycle = polyp and medusa

Question 7

3 things all Cnidarians have?

Answer 7

1. radial symmetry (oral/aboral)
2. only 2 layers of living tissue (epidermis and gastrodermis) with non living mesoglea = diploblastic
3. tentacles surrounding mouth - single opening to digestive system

Question 8

where does waste come out?

Answer 8

mounth - they have an incomplete digestive system - lacking an anus

Question 9

define Cnidae

Answer 9

• nettle / stinging thread,
  protein capsule with opening (operculum) + coiled tube. secreted by golgi apparatus in a cnidoblast
  chemical/ tactle stimulation.

Question 10

how do Nematocysts attack?

Answer 10

pierce, wrap or stick to prey
as food collection, defence, locomotion,
fires once

Question 11

Cnidarians are carnivorous true or false?

Answer 11

true but they do feed on Phytoplankton with symbiotic algae (corals)

Question 12

do Cnidarians have gills?

Answer 12

no

Question 13

after fertilisation what is created?

Answer 13

planula larvae

Question 14

what are the simple characteristics of phylum Cnidaria

Answer 14

no head
2 cell layer
tissues but very few
no organs
no brain
no seperate muscles

Question 15

what are the 4 classes of Cnidaria?

Answer 15

1. Hydrozoa
2. Anthozoa
3. Scyphozoa
4. Cubozoa

Question 16

define Class Hydrozoa

Answer 16

polyp + medusa (with velum)

Question 17

define class Anthozoa

Answer 17

polyps with mesentries . no medusa

Question 18

define class Scyphozoa

Answer 18

medusa dominant (no velum) transient polyp

Question 19

define class Cubozoa

Answer 19

medusa with 4 sides + velum - tiny polyp

Question 20

what is a free floating hydrozoan colonie withere medusa and polyps are present simultaneously?

Answer 20

class Hydrozoa, Order Siphonophora

Question 21

what is a Hydrocoral?

Answer 21

a small number of colonal species that secrete a calcareous skeleton. mainly in warm waters “fire coral” = dactylozooids

Question 22

define the characteristics of the Class Anthozoa

Answer 22

absense of a medusa, absense of operculum and cnidocil, circular mtDNA rather than linear , presence of ciliated grooves (siphonoglyph) in the pharyngeal wall leading from the mouth
coelenteron partitioned by distinct sheets of tissue (mesentries/septa)

Question 23

how many species of Anthozoa?

Answer 23

6000 - all marine

Question 24

what are the species of Anthozoa?

Answer 24

sea anenomes, sea fans, corals , sea pens

Question 25

how does a sea anenome eat?

Answer 25

nematocysts/ tentacles for capture

Question 26

what is Acrorhagi

Answer 26

appendages under the tentacles for defence = very potent nemotocysts

Question 27

Class Anthozoa has two sub classes, what are they?

Answer 27

1. Zoantharia (Hexacorallia) = sea anenomes. hard coral
2. Alcyonaria (octocorallia) = sea fans, soft corals, seapens

Question 28

define Zoantharia characteristics

Answer 28

numurous tentacles around mouth (usually in multiples of six) and 6 pairs of primary mesentries . 1 pair siphonoglyphs

Question 29

define Alcyonaria characteristics

Answer 29

8 tentacles around mouth and 8 pairs of primary mesentries, genrally single siphonoglyph

Question 30

reef building corals are:

Answer 30

hermatypic scleractinian corals

Question 31

non-reef building corals are

Answer 31

Ahermatypic

Question 32

hermatypic corals can live in water less than 18 degrees true or false?

Answer 32

false. water must be over 18

Question 33

loss of Zooxanthellae causes

Answer 33

coral bleaching - caused by prolonged temperature change and increased UV

Question 34

defining characteristic of Scyphozoa - jellyfish

Answer 34

asexual reproduction by strobiliation, a few hundred species, all marine, can get up to 2m across, medusoid body

Question 35

what are the three sensory receptors in jellyfish?

Answer 35

1. Statocysts (balance,
2. ocelli ( light)
3. lappets (touch)

Question 36

what is a statocyst?

Answer 36

each rhopalia adjacent to a sensory cilia - each tube weighted with statolith.

Question 37

what is a rhopalium (a)?

Answer 37

houses the sensory structures

Question 38

how do the sensory structures work?

Answer 38

when the jelly is upright everything is hanging downwards, when the medusae tilts -> statocyst presses against cilia -> nerve generate action potentials -> orientation occurs

Question 39

what does an ocellus detect?

Answer 39

only light, not real images

Question 40

are polyps ight sensitive?

Answer 40

no, they have no ocelli

Question 41

define Cubozoa

Answer 41

medusa with box like body
rhopalia bear complex lensed eyes.

Question 42

how long can the tentacles of a box jelly be?

Answer 42

30cm - waspsting
can kill a human in 3 minutes

Question 43

what is an Irukandji?

Answer 43

Carukia barnesi - small 2.5cm jelly with a venom neurotoxin similar to funnel web spiders and scorpion

Question 44

Cubozoa have pupils true or flase?

Answer 44

true but severaly under focused

Question 45

what is the defining characteristics of Ctenophora?

Answer 45

1. plates f fused cilia arranged in rows
2. adhesive prey capturing cells (colloblasts)

Question 46

how many species of Ctenophores are there?

Answer 46

100 - all marine and most planktonic

Question 47

distinguishing feature of a ctenophore?

Answer 47

their comb “ctenes” in rows , they beat simultaneously and can give off bright colours
and colloblasts (sticky structures that capture food)