10. Cnidaria Flashcards

1
Q

Spherical Symmetry

A

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

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2
Q

Radial Symmetry

A

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
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3
Q

Biradial Symmetry

A

Variant of radial

  • Radial symmetry with an aspect of bilateral symmetry
  • Comb Jellies(ctenophora) tentacles
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4
Q

Bilateral symmetry

A

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
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5
Q

Cephalization

A

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

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6
Q

Frontal plane

A

Coronal Plane

- Divides body into dorsal and ventral halves

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7
Q

Sagittal Plane

A

Divides body into left and right

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8
Q

Transverse plane

A

Cross section

- Divides body into anterior and posterior halves

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9
Q

Anterior

A

Head end

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10
Q

Posterior

A

Tail end

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11
Q

Dorsal

A

Back side

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12
Q

Ventral

A

Belly side

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13
Q

Medial

A

Midline of body

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14
Q

Lateral

A

Left and right sies

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15
Q

Distal

A

Parts farther from the middle of the body

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16
Q

Proximal

A

Parts nearer from the middle of the body

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17
Q

Cnidaria & Ctenophora similarity

A
  • Radial / Bilateral symmetry
  • Cell-tissue level organization
  • Diploblastic
  • Blind gut
18
Q

Cnidaria

A
  • Mostly sessile or slow moving
  • Efficient predetors
  • Algae are frequent mutualists
  • Mostly marine, some fresh water
  • Abundant in shallow marine habitat
19
Q

Two morphological types of Cnidarians

A

Polyp - Sedentary or sessile

Medusa - Floating or free-swimming

20
Q

Sessile

A

Fixed in one place

21
Q

Sedentary

A

Little movement

22
Q

Substratum

A

Solid surface

23
Q

Polyp form of Cnidarian

A
  • Tube shape
  • Sedentary or Sessile
  • Mouth surrounded by tentacles
  • Can be attached to substratum by pedal disc
24
Q

Medusa form of Cnidarian

A
  • Umbrella - Shaped
  • Floating or free swimming
  • Mouth centered on concave side
  • Tentacles extend from rim of umbrella shape
25
Q

Commonality of Cnidarian forms

A
  • Diploblastic
  • mesoglea between two tissue layers
  • Mesoglea is thicker in the medusa form - buoyancy
26
Q

Cnidarian Respiration

A

Diffusion

27
Q

Cnidarian Digestion

A
  • Mouth opens into gastrovascular cavity
  • Blind gut
  • Extra & Intracellular digestion
  • Undigested material carried back into the cavity by amoeboid cells
28
Q

Cnidarian Reproduction

A
  • 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
29
Q

Locomotion

A
  • Some polyps are sessile
  • Hydra and sea anemones can move slowly by gliding on pedal disc
  • Sea anemones occasionally swim
30
Q

Cnidocyte

A

Cell that holds cnida

31
Q

Cnida

A

Stinging organelle

  • Nematocyst - Most common type of cnida
  • Many nematocyst have a toxin which paralyzes prey
32
Q

Cnidocil

A

Triggers the nematocyst to fire

33
Q

Hydrozoa

A

Typically asexual polyp and sexual medusa

  • Hydra has only polyp
  • Others only have medusa
34
Q

Scyphozoa

A

True jellyfish

  • Dioecious
  • Internal fertilization
  • Medusa and polyp during life cycle
35
Q

Life cycle of Aurelia

A
  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)
36
Q

Cubozoa

A

“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
37
Q

Anthozoa

A
  • 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
38
Q

Ctenophora

A
  • Biradial symmetry
  • All marine, especially in wam waters
  • Commonly called “Sea walnuts” or “Comb Jellies”
  • No nematocysts except Haeckelia rubra
39
Q

Symbiosis of Clownfish & Cnidarians

A

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

40
Q

Anemone & Clownfish Benefits

A
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
41
Q

Crab-Cnidarian symbiosis

A

Crabs have anemones on claws - genus Lybia

- Steal anemone if missing and tear in half - inducing asexual reproduction

42
Q

Symbiosis with Zooxanthellae

A

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