Chapter 7: Cnidarians and Ctenophores Flashcards by Erin Wood

There are over ___ species of Phylum Cnidaria

900

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Where can you find Phylum Cnidaria?

Marina habitats; some freshwater

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A ____ is a unique defining feature of cnidarians.

cnidocyte

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What is the function of a cnidocyte?

Plays central role in prey capture and defense

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Each cnidocyte houses a ____ which is a fluid-filled membraneous capsule containing a long tubular invitation.

cnida

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How many types of cnida are there?

3 types

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The most common type of cnida is called a _____.

nematocyst

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What is on the surface of a nematocyst?

spines or barbs

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When a Cnidocyte is stimulated what happens?

A nematocyst tubule everts explosively out of the cell

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What does the nematocyst tubule do when it has been expelled?

Penetrates skin or surface and releases toxins that sting and/or trigger paralysis.

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The trigger for a nematocyst tubule to fire is called ____.

cnidocil

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Cnidocil is a type of ____

mechanoreceptor

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Where are Cnidarians most abundant?

Shallow marine habitats especially in tropical regions and warm areas

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True/False: Humans commonly consume Cnidarians

False: they are food for other animals but rarely for humans

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What are some importances of Cnidarians?

Reef-building corals
Provide substantial food for humans
Ecotourism
Jewelry and ornaments
Coral rock used for sculptures and buildings

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Cnidarians are ____ meaning they have two morphological types

Dimorphic

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What are the two morphological types of Cnidarians?

Polyp and Medusa

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Describe the lifestyle of a polyp?

Sedentary or sessile (does not move around)

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Describe the lifestyle of a medusa?

Floating or free-swimming

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Describe the oral end of a polyp

Mouth surrounded by tentacles
Leads to blind gut

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describe the aboral end of a polyp

Attached to substrate; via pedal disc

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What type of reproduction does a polyp do?

Asexual: Budding, Fission,

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A unique form of asexual reproduction in polyps is the laceration of the ____ ____. Describe this process

Pelvic disc; torn tissue will be broken off and develop into tiny new polyps

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What type of specific symmetry does a medusa have? What overall symmetry?

Tetramerous; raidial

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What does tetramerous mean?

Body parts are arranged in 4's

On a medusa, the mouth is centered on the ____ side

concave

Where are the tentacles on a medusa?

They extend from the rim of the bell

True/False: Colonial Polpys can move with the help of ocean currents

False: they are permanently attached to wherever they began to form

How do hydras/anemones move?

Gliding on their pedal disc

True/False: Medusae move freely

True: they have the easiest time moving

Medusae are monoecious/dioecious

Dioecious (have either male or female sex cells)

Name the types of digestion a cnidarian performs and describe them

Extracellular- enzymes are secreted by gland cells in the cavity Intracellular- nutritive-muscular cells phagocytize food particles

____ cells remove undigested particles that are eventually expelled from the body.

Ameboid

How many layers in the body wall of a hydra composed of? What are they?

2; epidermis and gastrodermis

Which layer is the epidermis

the outer layer

What lies between the layers of the body wall

Mesoglea

Describe the Mesoglea

Gelatinous extracellular matrix Thicker in medusae

What cells make up the gastrodermis (4)

Nutritive-muscular cells, interstitial cells, gland cells, cnidocytes

Nutritive-muscular cells contain ____ and form the _____ layer.

myofibrils; muscular

The gastrodermis also contains a _____ skeleton.

hydrostatic

What is the function of the hydrostatic skeleton?

Increases the volume of water in the gastrovascular cavity

What is special about interstitial cells?

They are undifferentiated stem cells and can transform into other cell types

What do gland cells do?

secrete digestive enzymes

What cells make up the epidermis? (6)

epitheliomuscular cells, interstitial cells, gland cells, cnidocytes, sensory cells, nerve cells

Epitheliomuscular cells form most of the ____.

epidermis

What are the functions of epitheliomuscular cells?

cover body, muscle contraction

What do sensory cells do?

synapse with nerve cells

What is the function of nerve cells?

Form synapses with sensory cells and other nerve cells Respond to stimuli

Where is a nerve net located?

base of epidermis and gastrodermis

What are the 6 classes of Cnidaria?

Anthozoa, Myxozoa, Staurozoa, Scuphozoa, Cubozoa, Hydrozoa

Most class hydrozoa organisms are in ____ and ____ form

marine; colonial

What are the stages of class hydrozoa?

asexual polyp and sexual medusa

What is the exception to class hydrozoa in terms of reproductive forms?

Hydra; does not have a medusa stage

What are statocysts? Where are they located?

Small organs of equlibrium; on the bell of a hydrozoan

What are ocelli?

Light sensitive organs

What is an example of a Siphonophore Hydrozoan?

The Portuguese Man-of-War

What is unique about the Portuguese Man-of-War?

They have a modified polyp that is an air sac filled with secreted gas

Class Scyphozoa are also called ____ ____.

true jellies

What is an example of Class Scyphozoa?

The Lion's mane jellyfish

What are the different bell shapes present in Class Scyphozoa?

shallow saucer, helmet, goblet

The ____ in Class Scyphozoa is the sense organ.

Rhopalium

Each Rhopalium in Class Scyphozoa has a ____ (sense organ) that aids in balance.

statocyst

Some Rhopalium in Class Scyphozoa has a ____ which is a simple photoreceptor.

ocellus

True/False: As Scyphozoans develop they have no parental care and develop in the seawater

True; parents do not care for offspring

In Scyphozoans planula larva will develop into a ____.

scyphistoma

Describe a scyphistoma

Hyrda-like form

The process by which a ephyrae becomes a strobila is called ____.

strobilization

What happens to an ephyrae when they break free?

They grow into mature jellies

True/False: Class Staurozoa do not have a medusa phase.

True

Describe the anatomy of a Staurozoan

Stalked body, basal adhesive disc that can attach to substrate with clusters of nematocysts

What type of reproduction does Class Staurozoa do?

Sexual

The predominant body form of Class Cubozoa is a ____.

medusa

Describe the shape of the bell in class Cubozoa

Box shaped

Rhopalia are sensory structures in Class Cubozoa that contain what?

6 eyes each

What is the main food of Class Cubozoa?

fish

Some species of Class Cubozoa exhibit complex _____ ____. Such as ( EX.)

Mating Behaviors; males pass spermatophores to female for fertilization

What is an example of Class Cubozoa that is found in Austrialia

Irikanji jellyfish

How many species make up Class Myxozoa?

2180+ species

Class Myxozoa is made up of ____ _____.

obligate parasites

What are the two aquatic hosts for Class Myxozoa?

Fish and Annelid worms

What is bad about Class Myxozoa? (Economic Impact)

They damage commercially valuable fish

What happens to a fish infected by Class Myxozoa?

They contract whirling disease which causes deformities and decreases the ability to swim.

Class Anthozoa are also called what?

flower animals

Do Class Anthozoa have a medusa stage?

What are the 3 subclasses of Anthozoa?

Zoantharia/Hexocorallia, Ceriantipatharia, Octocorallia

What are examples of Zoantharia/Hexocorallia?

sea anemones, hard corals

Zoantharia/Hexocorallia have a ____ body plan meaning they are based on 6 or multiples of 6.

Hexamerous

What are example of Ceriantipatharia?

Tube anemones and Thorny corals

What are examples of Octocorallia?

Soft corals (sea pens, sea fans, sea pansies)

Octocorallia are ____ meaning they are built on a plan of 8.

octomerous

Zoantharian Corals live in what?

calcareous cups made of calcium carbonate

Gastrovascular cavities of Octocorallian coral polyps communicate through ____ which is a system of gastrodermal tubes.

solenia

Soft corals contain ____ a stiff yet flexible protein.

Gorgonin

What is the function of gorgonin?

Structural support

What animal interaction occurs in coral reefs?

mutualism

What is overenrichment?

Dumping too many nutrients into the ocean

What are some threats facing coral reefs?

Overfishing, pesticides, oil spills, climate change, tourists, coral bleaching

What is coral bleaching?

A process in which the water becomes too warm and corals become white and brittle and die. Zooxanthellae are expelled when under stress.

Describe the structure of Ctenes

8 longitudinal rows of transverse plates bearing long cilia

Ctenes have a ____ level of organization

tissue

Are Ctenes diploblastic or triploblastic?

diploblastic

_____ is the organ of equilibrium in Ctenes

Statocyst

Are statocysts monoecious or diecious?

monoecious

Chapter 7: Cnidarians and Ctenophores Flashcards

(103 cards)