Cnidarians Flashcards

1
Q

what are some general body traits of cnidarians?

A
  • two cell layers (epidermis and gastrodermis) and mesoglea in between
  • radial symmetry
  • tentacles around mouth
  • one body opening (mouth = anus)
  • gametes produced and stored in gastrovascular cavity
  • nerve nets but no CNS
  • muscles formed from specialized dermal cells
  • carnivorous
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2
Q

what are some unique body traits of cnidarians?

A
  • two potential body plans (polyp/medusa) + alternation of generations
  • cnidae (organelles) found in cnidocysts (cells)
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3
Q

what are the two main types of cnidarian skeletons?

A
  • calcium carbonate
  • hydrostatic
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4
Q

what is the genus name of the symbiotic dinoflagellate found in many corals?

A

symbiodinium

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5
Q

what are the three types of specialized polyps in hydrozoic colonies?

A

gonozooids = reproduction
gastrozooids = digestion
dactylozooid = defense

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6
Q

what are the two layers of cnidarian bodies and the matrix in between?

A
  • epidermis (outermost) and gastrodermis (innermost)
  • mesoglea in between
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7
Q

what symmetry do cnidarians have?

A

radial

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8
Q

what is the structure of a cnidocyte?

A

contains a cnida that consists of a capsule and tube with coiled thread structures inside

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9
Q

describe how cnidae can be triggered

A
  • mechanoreceptors and chemoreceptors on cnidocil (modified cilia) detect triggers
  • shaft shoots out and expels thread
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10
Q

what are the three types of cnidae?

A
  • nematocyst (penetrant and toxic)
  • ptychocyst (adheres to prey)
  • spirocyte (lassos prey)
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11
Q

what are the four classes of cnidarians?

A

anthozoa, cubozoa, scyphozoa, hydrozoa

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12
Q

what traits does anthozoa have?

A
  • anemones, corals
  • solitary or in colonies
  • no medusa life stage
  • can have either a hydroskeleton or calcified skeleton
  • mesenteries in gut from aboral to oral ends
  • three types of nematocyst containing tentacles: acontia (thin structures from stalk), acrorhagi (stubby structures forming a ring), catch tentacles (long structures near mouth)
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13
Q

what traits does hydrozoa have?

A
  • polyp is dominant life stage, uses medusa for reproduction
  • colonial polyps connected by stolons and shares gastrovascular system
  • polyps can specialize (polymorphism) into gastrozooids, gonozooids or dactylozooids
  • colony encased in perisarc sheath (chitin + protein)
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14
Q

what traits does scyphozoa have?

A
  • jellyfish
  • dominant medusa life stage
  • planula develops into scyphistoma (polyp)
  • scyphistomae stobilate to release ephyra (new medusa)
  • use rhopalia containing statocysts to sense gravity
  • additional sensory cells are ocelli (light) and tactile lappets (touch)
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15
Q

how are myxozoans unique?

A
  • parasitic
  • polar capsules release spores into host that rupture
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16
Q

what traits does cubozoa have?

A
  • box-like medusa form with tentacles at each corner
  • more developed nervous system
  • no strobilation
  • planula forms polyps which bud off to form medusae
17
Q

what function does the mesoglea have?

A
  • structural support
  • forms connective tissue between two body layers
  • helps circulate nutrients
18
Q

what is the manubrium?

A

tube like structure that connects mouth to stomach