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BDV101 > Phylum Cnidaria > Flashcards

Phylum Cnidaria Flashcards

1
Q

The phylum name comes from Cnidaria, the Greek word ____ meaning ___

A

knide= nettle and aria=like/connected wit

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2
Q

Cnidarians have diversified into a wide
range of ___ and _____

A

sessile
motile forms

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3
Q

Example of Cnidarians

A

Sea-jellies
Coral colonies
Sea anemones
Sea pens
Sea fans

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4
Q

Cnidarians are an ancient phylum of

A

eumetazoans

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5
Q

Cnidarians body type

A

Radial symmetry

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6
Q

Cnidarians body organization

A

Diploblastic (2 primary germ layers - ecto and endo; lacks mesoderm)

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7
Q

Jelly-like layer between endo and ecto but not a tissue layer

A

Mesoglea

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8
Q

The basic body plan of a cnidarian is a__________, the _______.

A

sac with a central digestive compartment

gastrovascular cavity

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9
Q

Alternation of generations in cnidarians: 2 body plans

A

Polyp and medusa

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10
Q

Illustrate polyp and medusa

A

-

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11
Q

Fig. 2. Polyp and medusa forms of cnidarians.
The body wall of a cnidarian has two layers of cells: an outer layer of ______ (darker blue; derived from ectoderm) and an inner layer of ______ (yellow; derived from endoderm)…..

A

epidermis
gastrodermis

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12
Q

Fig. 2. Polyp and medusa forms of cnidarians.
_____ begins in the ____ and is completed inside _____ in the gastrodermal cells.

Sandwiched between the epidermis and gastrodermis is a gelatinous layer, the ____.

A

Digestion
gastrovascular cavity
food vacuoles
gastrodermal cells

mesoglea

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13
Q

Characteristics continued:
Body cavity: ____
Digestive system: ____

A
  1. Acoelom (body plan that lacks true body cavity called coelom)
    • Mouth
      - Gastrovascular cavity (first)
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14
Q

are cylindrical forms that adhere to the substrate by the aboral end of their (the end opposite the mouth) and extend their tentacles, waiting for prey.

Examples:

A

Polyps

Ex: Hydras, Sea anemones

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15
Q

Although polyps are primarily sedentary, many
polyps can move slowly across their substrate using _____ of their body.

Reminders: When threatened by a predator, some sea anemones can detach from the substrate and “swim” by bending their body column back and forth, or thrashing their tentacles

A

muscles at the aboral end

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16
Q

Resembles a flattened, mouth-down version of the polyp. It moves freely in the water by a combination of passive drifting and contractions of its bell-shaped body

Example:

A

Medusa (Plural: medusae)

Ex: Free-swimming jellies

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17
Q

Cnidarians reproduction:

A

Sexual:
Asexual: Budding and regeneration

18
Q

Life cycle of the Hydrozoan “Obelia”

A

The life cycle of the hydrozoan obelia involves both asexual and sexual reproduction:

  1. Asexual Reproduction (Budding)
  2. Budding creates colonies of polyps
  3. These Polyps produces medusae (jellyfish) thru sexual reproduction (meiosis)
  4. Medusae releases eggs and sperm in the water =Fertilization
  5. The zygote develops into Planula (larva)
  6. Planula settles and develops into a polyp….
    Mature polyp reproduces asexually thru budding completing the cycle
19
Q

Cnidarians have no organs or organ systems. Gas exchange is done by

A

Diffusion

Circulation and Respiration: Diffusion
Excretion: Mouth

20
Q

Describe the nervous system of Cnidarians

A

Rudimentary nervous system
- Decentralized nerve net of interconnected neurons
- Nerve net encircles body (first) - coordinates nerves and muscles

21
Q

Defense against predators & Capture of Prey

A

Cnidocytes

22
Q

____ called ____ are stinging capsule

A

Cnidae
nematocysts

23
Q

A cnidocyte of a hydra. This type of cnidocyte contains a stinging capsule, the ____ , which contains a coiled thread. When a “trigger” is stimulated by touch or by certain chemicals, the thread shoots out, puncturing and injec ting poison into prey

A

nematocyst

24
Q

____ occur in their simplest forms in cnidarians. Cells of the epidermis (outer layer) and gastrodermis (inner layer) have bundles of microfilaments arranged

A

Contractile tissues and nerves

25
Q

The gastrovascular cavity acts as a _____ against which the contractile cells can work. When a cnidarian closes its mouth, the volume of the cavity is fixed, and contraction of selected cells causes the animal to change shape

A

hydrostatic skeleton

26
Q

Movement and Coordination of Cnidarians:

Movements are coordinated by a ____

Cnidarians have no brain, and the noncentralized nerve net is associated with ___ distributed around the body. Thus, the animal can detect and respond to stimuli from all directions.

A

nerve net.

sensory structures

27
Q

Four important Cnidarians Classes

A

Anthozoa
Scyphozoa
Hydrozoa
Cubozoa

28
Q

Polyps with a flowerlike appearance
Ø No medusa stage
Ø All marine, found all over the world

A

Class Anthozoa

29
Q

Class Anthozoa: A mouth opening is surrounded by tentacles bearing ___

A

Cnidocytes

30
Q

Example of Class Anthozoa

A

Includes sea anemones, corals, sea fans, and sea whips

31
Q

Class: Dominant stage is the medusa
Ø Polyp is absent or reduced
Ø Cup-shaped umbrellas
Ø Includes true jellyfish

A

Class Scyphozoa

32
Q

Species range from 2 cm in length to the largest scyphozoan species, ____, at 2 m across. Jellies display a characteristic bell-like body shap

A

Cyanea capillata

33
Q

Mostly marine
Ø Alteration of generation (polyp and medusa stages) is usually exhibited
Ø Includes hydroids, fire corals, and Portugese man-of- war

A

Class Hydrozoa

34
Q

Class Hydrozoa:
The characteristic shared by all of these species is that their gonads are derived from ____, whereas in all other cnidarians, they are derived from ___

A

epidermal tissue
gastrodermal tissue

35
Q

Exist only in the polyp form
- favorable conditions: reproduce
asexually by budding
- harsh conditions: reproduce
sexually forming resistant zygote

A

Hydrozoan: Hydra

36
Q

box jellyfish, are a relatively recent
evolutionary lineage within cnidarians. Ø They have a box-shaped medusa and well-developed
eyes, allowing them to detect light and navigate their
environment

A

Cuboza

37
Q

Cubozoans have muscular pads called _____ at the corners of the square bell canopy, with one or more tentacles attached to each pedalium. In some cases, the digestive system may extend into the____

A

pedalia

38
Q

Cubozoans typically exist in a ___ that develops from a larva. The polyps may bud to form more polyps and then transform into the medusoid forms

A

polyp form

39
Q

The_____ also known as a sea wasp or marine stinger, releases a toxin so powerful that it causes a rapid spike in blood pressure, which can cause cardiac arrest and lead to death

A

box jellyfish (Chironex fleckeri),

40
Q

Many jellies are ____. Food captured by ___ is transferred to specialized oral arms that lack nematocyst for transport to the mouth

A

bioluminescent
nematocyst- bearing tentacles

BDV101 (3 decks)

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