Chapter 7: Cnidarians and Ctenophores Flashcards
There are over ___ species of Phylum Cnidaria
900
Where can you find Phylum Cnidaria?
Marina habitats; some freshwater
A ____ is a unique defining feature of cnidarians.
cnidocyte
What is the function of a cnidocyte?
Plays central role in prey capture and defense
Each cnidocyte houses a ____ which is a fluid-filled membraneous capsule containing a long tubular invitation.
cnida
How many types of cnida are there?
3 types
The most common type of cnida is called a _____.
nematocyst
What is on the surface of a nematocyst?
spines or barbs
When a Cnidocyte is stimulated what happens?
A nematocyst tubule everts explosively out of the cell
What does the nematocyst tubule do when it has been expelled?
Penetrates skin or surface and releases toxins that sting and/or trigger paralysis.
The trigger for a nematocyst tubule to fire is called ____.
cnidocil
Cnidocil is a type of ____
mechanoreceptor
Where are Cnidarians most abundant?
Shallow marine habitats especially in tropical regions and warm areas
True/False: Humans commonly consume Cnidarians
False: they are food for other animals but rarely for humans
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
Cnidarians are ____ meaning they have two morphological types
Dimorphic
What are the two morphological types of Cnidarians?
Polyp and Medusa
Describe the lifestyle of a polyp?
Sedentary or sessile (does not move around)
Describe the lifestyle of a medusa?
Floating or free-swimming
Describe the oral end of a polyp
Mouth surrounded by tentacles
Leads to blind gut
describe the aboral end of a polyp
Attached to substrate; via pedal disc
What type of reproduction does a polyp do?
Asexual: Budding, Fission,
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
What type of specific symmetry does a medusa have? What overall symmetry?
Tetramerous; raidial
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?
No
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
