LESSON 3: CNIDARIANS Flashcards
Cnidarian: Body Plan
Radial and Biradial symmetry
body parts are arranged concentrically
around an oral-aboral axis
Radial symmetry
a type of radial symmetry in which only
two planes through the oral-aboral axis divide the animal into mirror
images because the body contains a paired structure
Biradial symmetry
All other eumetazoans have a primary ______________
bilateral symmetry
Stinging cells
Cnidocytes
Phylum Cnidaria is a group of more than _______species
9000
Stinging Organelle
Cnidae
Cnidarians are an ancient group with the longest fossil history of any
animal phylum, reaching back more than _______ years
700 million years
Cnidae come in several types, including the common __________.
nematocysts
In terms of movement, Cnidarians can be:
-Sessile
-Slow moving or Slow Swimming
Cnidarians are quite efficient predators of organisms that are much swifter and more
complex.
efficient predators
_______ frequently live as mutualists in the
tissues of cnidarians
Algae
Alagae reside in some ________________ and in reef-building
corals
freshwater hydras
The presence of algae in reef-building corals limits coral reefs to relatively_____________
shallow, clear water
Why do corals usually seen in shallow and clear water?
So that Algae that reside them can perform photosynthesis effectively
6 classes of Phylum Cnidaria
- Hydrozoa
- Scyphozoa
- Cubuzoa
- Anthozoa
- Staurozoa
- Myxozoa
These corals are an essential component of coral reefs, and reefs are
extremely ______________ in tropical waters
important habitats
Four classes of Cnidaria that were traditionally recognized
- Hydrozoa
- Scyphozoa
- Cubuzoa
- Anthozoa
been proposed for a group of odd animals
whose bodies resemble polyps with a medusa-like region on the top
Staurozoa
sixth cnidarian class of highly modified
parasitic forms
Myxozoa
Cnidarians prefer what conditions:
-Mostly Marine, some freshwater
-Warm Temperature
-Tropical Regions
-Shallow, clean Waters
__________ are usually found attached to mollusc shells, rocks,
wharves, and other animals in shallow coastal water
Colonial hydroids
_______________________________ occur in open seas and lakes, often far from shore
Floating and free-swimming medusae
Example Colonies that have floats or sails, where wind carries them
-Portuguese man-of-war
-Velella
Cnidarians sometimes live symbiotically with other animals, often as ___________on the shell or other surface of their host.
commensals
Some ________, _________, and ________eat hydroids bearing nematocysts and use these stinging structures for their own defense
ctenophores, molluscs, and flatworms
___________________ is used for jewelry and ornaments
Precious coral
________________ may be of some importance as food for commercially valuable fishes
Planktonic medusae
Certain hydroids and sea
anemones commonly live
on ___________________, giving the
crabs some protection
from predators
snail shells inhabited by hermit crabs
Cnidarians: Body Form
-Dimorphism
-often polymorphism
___________ are used for buildings
coral rock
Types of Cnidarians based on body forms
-Polyp (hydroid form)
-Medusa (jellyfish form)
has a sedentary or sessile lifestyle
Polyp (hydroid form)
has a floating or free-swimming existence
Medusa (jellyfish form)
Most polyps have___________
tubular bodies
The ____________ of the polyp is
usually attached to a
substratum by a pedal disc or
other device
aboral end
Polyps may reproduce asexually by:
-Budding
-Fission
-Laceration of the Pedal Disc
a knob of tissue forms
on the side of an existing polyp and
develops a functional mouth and
tentacles
budding
A bud that detaches from the polyp
that made it is a ________-
clone
Clones can also be formed by _______
fission
Polyps that do not bud are ________; others form _____________
-solitary
-clones or colonies
When buds stay
attached to the polyp
that made them, a
colony forms, and food
may be shared through
a ________________
common gastrovascular cavity (1 para sa tanan)
Polyp in a colony performs different functions, and they are called the __________
Zooids
Different Zooids
-Gastrozooids
-dactylozooids
-gonozooids
Polymorphic colonies are common in class _________
Class Hydrozoa
dactylozooids
for defense
gastrozooids
for feeding
gonozooids
for making sexually reproducing stages
Symmetry: body parts
arranged in fours
tetramerous symmetry
A colony that contains several body forms
polymorphic (Polymorphism)
Physical characteristics and movement of Medusae
-bell-shaped or umbrella-shaped bodies
-tetramerous symmetry
-free-swimming
Medusa: the _____ is usually centered on the
concave side
Mouth
The Tentacles of Cnidarians extend from the ____________
Rim of its Umbrella
Superficially, polyps and medusae seem very different, but each has retained the ____________ basic to the phylum
saclike body plan
two tissue layers with an extracellular matrix (ECM), both found in polyp and medusa
Mesoglea (jellylike layer)
Mesoglea is much thicker in _____
Medusa
The thick mesoglea in Medusa form _______, making it more ________.
-Bulk of the animal
-more buoyant
Scientific term (accepted term) of jellyfishes
Jellies
Locomotion: Colonial Polyps
Permanently attached to the substratum
Locomotion: Hydras
move freely across a substrate by gliding on their pedal disc
Hydras movement is aided by ____________
Mucous secretions
___________ move similarly on their pedal discs.
Sea Anemone
Hydras can also use a ____________ movement, looping along a surface by bending over and attaching their tentacles to the substratum
“measuring worm”
Mechanism of medusa in moving freely
Swim by contracting its bell which expels water from the concave (oral side)
The muscular contractions of medusa are antagonized by the compressed ____ and ________
mesoglea and elastic fibers within it
The exact life cycle varies among the classes, but in general a zygote develops into a _________
free-swimming planula larva
The planula settles and _________into a polyp
metamorphoses
Classes of cnidaria that life cycle includes polyp to medusa
Hydrozoa and Scyphozoa
Fertilization of cnidarian typically occurs in _______
open water
are all polyp but both sexual and asexual reproduction occur in the polyp phase
Sea anemones and coral (Class Anthozoa)
have a conspicuous medusoid form, although most also have a polypoid larval stage
sea jellies (class Scyphozoa)
typically have life histories that feature both a polyp stage and a free-swimming medusa stage
Colonial hydroids(Hydrozoa)
Different body parts of Cnidarians
-Gastrovascular Cavity
-Mesoglea
-Gastrodermis (Endodermal)
-Epidermis (Ectodermal)
-Mouth
-Tentacles
which communicates with cavities in the tentacles
Mouth opening to the Gastrovascular Cavity
The mouth may be surrounded by an elevated _________or by ____________ in the medusa stage
Manubrium or elongated oral lobes
Manumbrium is the _______ of the cnidarian, where mouth is found on its end (in polyp)
Stalk
Different Cell in Cnidarian
-Gland Cells
-Nutritive-Muscular Cells
-Ameboid Cells
-Interstitial Cells
-particularly abundant around the mouth and in the pedal disc of hydra
-discharge enzymes that initiate extracellular digestion
Gland Cells
Gland cells secrete _______
Mucus or Adhesive Material
-phagocytize many food particles for intracellular digestion
-usually tall columnar cells that have laterally extended bases containing myofibrils
Nutritive-Muscular Cells
can carry undigested particles to the gastrovascular cavity, where they are eventually expelled with other indigestible matter
Ameboid Cells
Mesoglea is what(generally and for hydrozoan)?
-Gelatinous ECM without fibers
-Cellular element in Hydrozoan Polyp
-undifferentiated stem cells found among the bases of the epitheliomuscular cells.
-Can differentiate into other cells
Interstitial Cells
lies between the epidermis and the gastrodermis and adheres to both layers
Mesoglea
In Scyphozoan medusae, mesoglea has _________
Ameboid cells
In Anthozoans, mesoglea contains ___________ and _________
-Ameboid cells
-Epitheliomuscular cells
-form most of the epidermis
-serve both for covering and for muscular contraction.
-has contractile function
-aids for locomotion
-intercellular food digestion
Epitheliomuscular cells
a layer of cells lining the gastrovascular cavity, consists chiefly of large, ciliated, columnar epithelial cells with irregular flat bases
Gastrodermis
Gastrodermis contains the cells?
-nutritive-muscular cells
-interstitial cells
-gland cells
-Cnidocytes (except for Hydrozoa)
Gonads are ____________ in most Cnidarians
Gastrodermal
The Epidermis contains what?
-Epitheliomuscular cells
-Interstitial cells
-Gland Cells
-Cnidocytes
-Sensory and Nerve Cells
Gonads are ____________ in Hydrozoa
Epidermal
-containing cnidae
-occur throughout the epidermis. -may be between the epitheliomuscular cells or housed in invaginations of these cells * -they are most abundant on the tentacles
Cnidocytes
Contraction of these fibrils, cause _____________
Shortening the body or tentacles.
Differentiation of Interstitial cells produces
- cnidoblasts
-sex cells,
-buds,
-nerve cells,
-and others, but generally not epitheliomuscular cells (which reproduce themselves).
are scattered among the other epidermal cells, especially around the mouth and tentacles.
Sensory cells
The free end of each sensory cell bears a _________
flagellum
of the epidermis are often multipolar (have many processes), although in more highly organized cnidarians, the cells may be bipolar (with two processes).
Nerve cells
With two processes
Bipolar
have many processes
Multipolar
inside of the undischarged thread may bear tiny barbs, or spines, as in the most common cnida
nematocyst
-Over 20 different types
-are tiny capsules contained within cnidocytes
-This end of the capsule is covered by a little lid, or operculum
-The inside of the undischarged thread may bear tiny barbs, or spines, as in the most common is nematocyst
Cnidae
The end of the capsule (cnidae) are covered with little lid called?
Operculum
Except in Anthozoa, cnidocytes are equipped with a triggerlike __________, which is a modified cilium
Cnidocil
Hydrozoa: found where? Form?
-Marine(few freshwater)
-Colonial in form (Some occur only in medusae and have no polyp stage)
Most Variable Class of Cnidaria
Class Hydrozoa
Example of Hydrozoa that has no medusa stage
Freshwater Hydras
- contains the stored larva of hydrozoans
-Reduce Medusae
Gonophores
Example of hydrozoa that has reduced medusae/ gonophores
Tubularia crocea
The common freshwater hydra is a ______________ and one of the few cnidarians found in fresh water
solitary polyp
Hydrozoa’s normal habitat is the underside of aquatic leaves and lily pads in cool, clean ______________________.
freshwater pools and streams
Example of hydrozoa that has symbiotic algae inside its gastrodermal cells. A bud with tentacles is attached to one side of the body
Green Hydras
The body of a hydra can extend to a length of __________ or can contract to a tiny, jellylike mass
25–30 mm
The pedal disc has gland cells that enable a hydra to __________________________
adhere to a substratum and also to secrete a gas bubble for floating
In the center of the disc of hydra may be an _________
excretory pore
hypostome, is encircled by ______________ that, like the body, can greatly extend when the animal is hungry
six to ten hollow tentacles
The mouth, located on a conical elevation called the __________
hypostome
Food for Hydras
-Small Crustaceans
-Insect Larvae
-Annelid Worms
Hydrozoan: In asexual reproduction, buds appear as ___________ of the body wall and develop into young hydras that eventually detach from the parent
outpocketings
Hydrozoan: In sexual reproduction, ___________ usually appear in autumn, stimulated by lower temperatures and perhaps also by reduced aeration of stagnant waters
temporary gonads
Hydrozoan: Testes or ovaries, when present, appear as __________ on the surface of the body
rounded projections
Hyrozoans: Eggs in the ovary usually ______________ and are fertilized by sperm shed into the water
mature one at a time
_______ is often used in laboratory exercises for beginning students to illustrate the hydroid type
Obelia
Structure of typical hydroid
-Base
-Stalk
-One or more terminal polyp (zooids)
Most zooids are feeding polyps called
hydranths, or gastrozooids
New polyps may be hydranths or reproductive polyps called
gonangia
Medusae are produced by _______within the gonangia
budding
Hydrozoan (medusa stage): The margin of the bell projects inward as a ___________, which partly closes the open side of the bell and functions in swimming
shelflike velum
is thumb-sized and commonly encountered on the Pacific Coast of North America, although the polyp stage has never been identified
Polyorchis penicillatus (medusa)
includes most of the larger jellies,
or “cup animals.”
Class Scyphozoa (Gr. skyphos, cup)
Hydrozoan: Medusa with typical tetramerous arrangement
Gonionemus
occurs commonly in caves and crevices in coral reefs. These fragile colonies branch in only a single plane and may be white, pink, purple, red, or red with white tips
Stylaster roseus (order Stylasterina)
Hydrozoan: are hydrozoans that form floating colonies
Siphonophores
Other hydrozoans secrete massive calcareous skeletons that resemble true corals thus sometimes called as
Hydrocorals
-Example of Siphonophore
-a rainbow-hued float, probably a modified polyp, which carries it at the mercy of winds and currents
Physalia (Portuguese man-of-war)
-Example of hydrocorals
-Stylaster roseus (order Stylasterina)
-Millepora (order Milleporina)
form branching or platelike colonies and often grow over the skeletons of gorgonians. They have a generous supply of powerful nematocysts that produce a burning sensation on human skin
Millepora (order Milleporina)
Common name: Fire Coral
A few Scyphozoans may attain a bell diameter of ________ and diameter of _________ long. (Provide Example)
Bell Diameter: Exceeding 2m
Tentacles: 60-70m
Example: Cyanea
Size Range of Scyphozoans
2-4 cm in diameter
The medusae of scyphozoans, unlike
those of hydrozoans, have no _________
no velum
A North Atlantic species
of Cyanea reaches a bell diameter exceeding 2 m. Many fishermen know it as “sea blubber.”
Cyanea capillata
Scyphozoans: _________ has eight
such notches. While others may have 4 to 16
Aurelia (L. aurum, gold)
-sense organ
-bears a statocyst
for balance, two sensory pits
containing concentrations of
sensory cells, and sometimes an
ocellus
rhopalium
Moon jelly ___________ (class Scyphozoa) is worldwide in distribution.
It feeds on planktonic organisms caught in mucus on its umbrella
Aurelia aurita
The tentacles, the manubrium, and often the entire body surface of
scyphozoans are well supplied with ____________
nematocysts
The sexes are separate in scyphozoans; their gonads are located in
the _____________
gastric pouches
Fertilization is __________ in scyphozoan, with sperm carried by ciliary currents into the
gastric pouch of the female
internal
Zygotes of scyphozoan may develop in _______-or may be brooded in folds of the
oral arms.
seawater
By a process called _________, the scyphistoma of Aurelia forms a series of saucerlike buds and becomes a__________
-strobilation
-Strobila
Aurelia: series of saucerlike buds
ephyrae
The ciliated planula larva attaches and develops into a _____________, a
hydralike form that may bud to make other polyps
scyphistoma
When the ______________, they grow into mature jellyfish
ephyrae break free
Class Staurozoa is commonly called __________
stauromedusans
A cnidarian class where all of its species does not have a medusa phase
Class Staurozoa
Staurozoa: The solitary polyp body is stalked
and uses an __________ to attach
to seaweeds and other objects on
the sea floor
adhesive disc
__________________ in class Staurozoa is an unusual cnidarian. The oral end of the animal resembles a medusa
Thaumatoscyphus hexaradiatus
Thaumatoscyphus hexaradiatus has ____________________, ending in tentacle clusters, surrounding the mouth.
eight extensions (“arms”)
-medusa is the predominant form
-the polyp is inconspicuous and in most cases
unknown.
-In transverse section, medusa bells are almost
square
-A tentacle or group of tentacles occurs at each
corner of the square at the umbrella margin
Class Cubozoa
Cubozoa: The base of each tentacle is
differentiated into a flattened, tough
blade called a ____________
Pedalium
Cubozoa: ____________each house six eyes, of three different types, in addition to other
sense organs.
Rhopalia
The umbrella margin of Cubozoa is not scalloped, and the subumbrella edge turns inward to form a _________
velarium
increasing swimming efficiency, but it differs structurally
Velarium
-are obligate parasites whose typical life cycle has two aquatic hosts
-one of the smallest genomes in the animal
kingdom.
Myxozoans
two aquatic hosts of myxozoan
a fish and an annelid worm (sometimes a bryozoan)
Members of at least one species of Cubozoa exhibit complex mating behaviors,
including ___________ as the male passes a spermatophore to the female
twined tentacles
-is a large cubomedusa
called the sea wasp.
-Its stings are dangerous and sometimes
fatal.
-Witnesses have described victims as
covered with “yards and yards of sticky
wet string.”
Chironex fleckeri
____________ in trout develops when young fish eat an infected
annelid or when fish skin is penetrated by spiny parasitic spores
released from an annelid.
Whirling disease
The infection by myxozoa will spread by cell division by _______________
new cell growing inside older cells
Inside the trout, parasite cells divide and spread, colonizing ____________.
cartilage in the skull and spine
After cell division, very tough _________ develop and leave the fish
myxospores
The myxospores will be eaten by
Tubifex worms
Fish infected with whirling disease, ___________, exhibit skeletal deformities and odd behaviors, reducing survival
(Myxobolus cerebralis
Myxozoans have been known since the 1880s, with more than __________
species identified
2180 species
-The sister taxon to Myxozoa is freshwater cnidarian
-is an endoparasitic cnidarian that retains key
cnidarian features including cnidocytes with nematocysts
-has a free-living phase that resembles a cluster of medusae with distinct
tentacles, but produces an infective sexual stage that enters the oocytes of
fishes such as paddlefish or sturgeon
Polypodium hydriforme
Myxozoa: When Fish reproduce, Inside the oocytes, a planula-like larval stage feeds on yolk and develops into a ______
stolon
Myxozoa: When the fish host spawns and oocytes are released into freshwater,
the stolon ________________________
breaks into individual medusa-like sections
-“flower animals,” are polyps with a flowerlike appearance
-There is no medusa stage
-all marine and occur in
both deep and shallow water and in
polar seas as well as tropical seas
-They vary greatly in size and may be
solitary or colonial
-Many are supported by skeletons
-Biradial symmetry
-no special organs for respiration or excretion.
Class Anthozoa
are the
familiar and colorful “flower animals” of tide pools, rocks, and
pilings of the intertidal zone. Most, however, are subtidal, their
beauty seldom revealed to human eyes
Sea anemones
Example of Sea Anemone under class Anthozoa nga namention sa ppt ni sir
Bunodosoma grandis
Class Anthozoa has three subclasses:
- Zoantharia (or Hexacorallia)
- Ceriantipatharia
- Octocorallia (or Alcyonaria)
-composed of the sea anemones, hard
corals, and others
-Septa are paired on each side
Zoantharia
which includes only tube anemones and thorny corals;
Ceriantipatharia
containing soft and horny corals, such
as sea fans, sea pens, sea pansies, and others
Octocorallia
Zoantharians and ceriantipatharians
have a _______________ (based on
six or multiples of six) or polymerous
symmetry and have simple tubular
tentacles arranged in one or more
circlets on the oral disc.
hexamerous body plan
Examples of Octocorallian mentioned
-Orange sea pen (Ptilosarcus gurneyi)
-gorgonian
Octocorallians are __________ (built on
a plan of eight) and always have eight
pinnate (featherlike) tentacles arranged
around the margin of the oral disc
octomerous
Anthozoa: The gastrovascular cavity is large and partitioned by ________, or mesenteries, that are inward extensions of the body wall
septa
Sea Anemone size
Diameter: 5 mm or less to 100 mm
Length: 5 mm to 200 mm long
Sea anemones are cylindrical, with a
___________ arranged in one
or more circles around the mouth on
the flat oral disc
crown of tentacles
The slit-shaped mouth of sea anemones leads into a __________
pharynx
Example of Anemone fish that nestles in the tentacles of its sea anemone host. Anemone fishes do not elicit stings from their hosts but may lure unsuspecting other fish to become meals fort he anemone
Orangefin anemone fish (Amphiprion chrysopterus
-At one or both ends of the mouth of sea anemone is a ciliated groove called a ___________, which extends into the pharynx
-This create water currents directed into the pharynx
siphonoglyph
By studying the mucus of anemone fishes, biologist __________ was able to develop a protective lotion for swimmers.
Amit Lotan
Zoantharian Coral: Stony corals look like miniature sea anemones that live in_______________ they themselves have secreted
calcareous cups
is not a reef-building coral (ahermatypic) and has no symbiotic zooxanthellae in its tissues
Tubastrea sp. (Cup coral)
The polyps of _____________, a zoantharian coral are tightly withdrawn in the daytime but open to feed at night
Montastrea cavernosa
Like that of anemones, a coral polyp’s
gastrovascular cavity on zoantharian corals is subdivided by septa arranged in multiples of six (hexamerous), and its hollow tentacles surround the mouth, but there is no _________
no siphonoglyph
Boulder star coral, __________________
(subclass Zoantharia, class Anthozoa).
Colonies can grow up to 10 feet (3 m) high.
Montastrea annularis
Almost all are colonial in Octocorallian Corals, and the gastrovascular cavities of polyps in colonies communicate through a system of gastrodermal tubes called __________
solenia
Octocorals include
-soft corals
-sea pansies
-sea pens
-sea fans
-other gorgonian corals (horny corals).
Octocorallian Corals: These corals have
an endoskeleton of__________, often with a hardstructural protein, which may form an axial rod
limy spicules
A soft coral, _______________ (order
Alcyonacea, subclass Octocorallia, class Anthozoa),on a Pacific coral reef. The showy hues of this soft coral vary from pink and yellow to bright red and contribute much color to Indo-Pacific reefs
Dendronephthya sp.
The graceful beauty of octocorals—in
hues of yellow, red, orange, and
purple—helps to create the
_________________ of coral reefs
“submarine gardens”
Gorgonin has chemical similarities to __________and to _________; it is
responsible for structural support in horny corals, including gorgonians
keratin and to collagen
Soft corals have fleshy bodies with calcareous spicules in the mesoglea, but
the skeletons of other octocorals typically combine fused or separate
spicules with a stiffened yet flexible protein called _________.
gorgonin
Because skeletal structures are secreted within the mesoglea, most octocorals have an _____________
endoskeleton
among the most productive of all ecosystems, and their diversity of life forms is rivaled only by tropical rain forest
Coral Reefs
Reef-building corals have mutualistic algae (_________________) living in
their tissues
zooxanthellae
Coral reefs are large formations of _______________ in shallow tropical seas laid down by living organisms over thousands of
years
calcium carbonate (limestone)
The most important organisms that take dissolved calcium and
carbonate ions from seawater and precipitate it as limestone to form
reefs are
reef-building corals and coralline algae
Some octocorals and hydrozoans (especially __________________ the “fire coral,” contribute in some measure to the calcareous material, and an enormous variety of
other organisms contribute small amounts
Millepora spp.
Zooxanthellae recycle ___________________________ that otherwise
would be lost, and they enhance the ability of the coral to deposit calcium carbonate.
phosphorus and nitrogenous waste compounds
The highly beneficial symbiosis between corals and zooxanthellae is threatened by _____________ where corals become white and
brittle after expelling their zooxanthellae.
coral bleaching
Zooxanthellae needs sunlight to perform photosynthesis, reasons why they are usually found in ______ and ______ waters.
30 degrees south and 30 degrees North
