Cnidarians Flashcards

1
Q

What other Phlyum was paired with Cnidarians?

A

Ctenaphoras

(In phylum Coelenterata with Cnidarians but no longer classified as that

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2
Q

Give examples of Cnidarians.

(3 given examples in the slides)

A

Jellyfish, sea anemones, corals

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3
Q

Two forms of locomotion exhibited by Cnidarians.

(still and moveing)

A

Sessile and Free-swimming

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4
Q

What type of nutrition do they require?

(prey or predators)

A

Predators.

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5
Q

What type of organization do they have?

(Higher than porifera).

A

Tissue level organization

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6
Q

Skeleton may be made of what?

(3 things)

A

Hydrostatic, Calcium carbonate, chitin

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7
Q

What is the phlyum named after?

A

Its iconic cells cnidocytes or cnidae present in cnidocytes.

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8
Q

Habitat of cnidarians?

A

Marine & freshwater

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9
Q

Type of organization

A

Tissue level organisation

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10
Q

Type of symmetry for ctenophores?

A

Like ctenophores: Radial or biradial

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11
Q

Type of gut for ctenophores and cnidarians?

(complete or incomplete?)

A

Incomplete gut

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12
Q

Where does extracellular digestion occur?

A

Gastrocavity or gastrodermal cells

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13
Q

Two sense organs present in cnidaria

A

Statocyst and ocelli

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14
Q

What type of coelom?

A

Acoelomate (do not have one)

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15
Q

What are to two life forms of cnidarians?

A

Polyp and medusa

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16
Q

Describe the polyp form.

A

Tubular, sessile, mouth leads to gastrovascular cavity, aboral end attach to substrate. Asexual reproduction, polymorphism , modular colonies.

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17
Q

How do polyps reproduce asexually?

A

Budding, fission and pedal laceration (fragmentation)

18
Q

Describe the medusa form.

A
  • Tetramerous
  • Bell shape
  • Mouth on concave side of the bell.
  • Tentacles on the rim of the medusa.
  • Free-swimming
19
Q

What sensory structures are present in the medusae form?

A
  • Statocyst
  • Ocelli
20
Q

How many germ layers do the mesdusa have?

A
  1. They are diploblastic.

(epidermis & gastrodermis) middle is mesoglea.

21
Q

What are the 5 cells of Cnidarians ?

A
  1. Epitheliomuscular
  2. Interstitial
  3. Mucus gland cells
  4. Cnidocytes
  5. Sensory cells.
22
Q

What is the purpose of the epitheliomuscular cell?

A

Affect muscular contraction of the outter epidermis.

23
Q

What causes contractions in the cnidaria outer epidermal cells?

A

Myofibrils

24
Q

What is the purpose of mesoglea ?

A

Jelly like, thickness vary with different cnidaria,** supports and acts as an elastic skeletal.**

25
Q

Nerve Net

(location, what causes nerve action potential, what is it?).

A
  • Is a diffused nervous system.
  • located at the base of the epidermis and gastrodermis.
  • Nerve action potentials transmited by neurotransmitters.
26
Q

Explain the life cycle of a typical Cnidarian

A

Zygote developed into a planulae -> settles on a substrate -> planulae forms into polyp-> asexually form more polyps + medusae -> reproduce sexually.

27
Q

Name the 4 classes of the Cnidaria

A

Hydrozoa
Scyphozoa
Cubozoa
Anthozoa

28
Q

Example of the hydrozoa

A

Fire corals

29
Q

Key features of the Hydrozoa

A
  • Velum present
  • 4 radial canals
  • Acellular mesoglea
  • Hydromedusae
  • Polyp conspicous
  • Manbrium in which the mouth is at the end.
  • Colonial
  • Marine
  • Gametes release outside the body
30
Q

Example of the Scyphozoa

A

Upsidedown jelly fish

31
Q

Key features of the scyphozoa

A
  • Bell margin scalloped
  • Have lappets
  • Lappets have sensory structure called Rhopalium
  • Free swiming
  • Medusae dominant
  • Tentacles on subumbrella side
  • Mouth leads to stomach
  • nerve net
  • No velum
  • distinct sexes
  • reproduce sexually
    *
32
Q

Describe cubozoa

A
  • Strong swimmer
  • Medusoid stage dominant
  • Polyp is inconspicuous or absent
  • tentacles at corner at the Pedalium
  • 24 well developed eyes
  • Have rhopalia
  • Margin not scalloped
  • Boxed shaped in transverse section.
33
Q

Example of cubozoa

A

Box jellyfish

34
Q

Key characteristics of anthozoa

A
  • Medusa stage absent
  • coral polyp
  • biradial symmetric
  • polyp more complex and larger than other stages.
  • have amoeboid mesenchyme cells
  • Mouth leads to Pharynx
  • Solitary or colonial
  • marine
  • have 3 subclases: main subclasses are Hexacorallia and Octocorallia.
35
Q

Which subclass covers hard corals ?

A

Hexacorallia

36
Q

Which subclass of anthozoa covers soft corals?

A

Ocotocorallia

37
Q

Difference between hexacorallia and Octocorallia.

A

Hexamerous vs octomerous
simpler tentacles vs pinnate tentacles

38
Q

About scleractinian

A
  • Have cups formed from Calcium carbonate named Calyx.
  • Have cups where polyp can retract to.
  • Skeleton secreted at base of polyp.
  • Gastrovascular connected by coensarc.
  • Sclerosepta sticks in true septa.
  • Skeleton made of aragonite.
39
Q

An example of the Scleractinian

A

Brain corals.

40
Q

Describe octocorallia

A
  • Solenia (gastrovascular cavity communicates through it)
  • 8 pinnate tentacles.
  • 8 unpaired septa.
  • cellular thick mesoglea
  • Horny protein or fused spicules endoskeleton
  • Cnidocytes in both layers.
  • colonial
  • Septa goes into the upper body.
41
Q

What is a key feature of cnidocytes?

A

Cnidae or nematocytes.

42
Q

Prey-capture in Cnidarian

A

Cnidocil triggered from hydrostactic pressure (high tensional and osmotic pressure or forces) and the hollow barbed or spiculated threads are released and they sting prey, release toxins and immobolize them.