Activity 3. Cnidarians

7/31/2019 Activity 3. Cnidarians

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Cnidaria (Grknide, nettle + L. aria; like orconnected with

With more than 9,000 species Cnidocytes = which contain stinging

organelles (cnidae)

Cnidae come in several types includingthe common nematocysts

Nematocysts are used only bycnidarians


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Phylum Coelenterata

Gr. koilos, hollow, + enteron, gut + L. ata,

characterized by


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BODY PLANS: Have two body forms MEDUSA & POLYPS

Have Radial Symmetry

Known for Cnidocytes contain stinging cells such as nematocyst

REPRODUCTION: Reproduce Sexually & Asexually

Free-swimming larva - planula

CNIDARIAN CLASSES:

o Anthozoa sea anemones and corals (polyps; no medusa stage)

o Hydrozoa fire corals, Portuguese man-of-war, hydras

o Scyphozoa jellyfish medusa form is dominant but may begin as polyp

o Cubozoa

box jellyfish & sea wasp


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Entirely aquatic (mostly marine)

With oral and aboral ends

Radial symmetry or biradial symmetryaround a longitudinal axis Radial symmetry = body parts are arranged

concentrically around an oral-aboral axis

Biradial symmetry = is basically a type of radialsymmetry in which only two plane through theoral-aboral axis divide the animal into mirrorimages

No definite head


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Exoskeleton or endoskeletonchitinous,calcareous, or protein components in

some Body with 3 layers: epidermis and

gastrodermis , mesoglea (acellular)

Gastrovascular cavity orcoelenteron(often branched or dividedwith septa) = with a single opening thatserves as mouth and anus


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Extensive tentacles usually encircling themouth or oral region

Special stinging-cell organelles calledcnidae, in particular nematocyst, ineither epidermis or gastrodermis or inboth

Monoecious and dioecious


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Two basic forms:

Polyps

Or hydroid form

Adapted to asedentary or sessile

life

Medusae

Or jellyfish form

Adapted for afloating or free-swimming existence


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Polyps

Have tubular bodies

Mouth surrounded by tentacles (defines theoral end)

Mouth leads into a blind gut orgastrovascular cavity

Aboral end is usually attached toasubstratum by a pedal disc or other device


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Reproduceasexually by:

Budding

Fission Pedal laceration

Zooids

buds that remains attached to the polyp:gastrozooids (for feeding)dactylozooids (for defense)gonozooids (for making sexually reproducing stages)


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Usually free-swimming

Have bell-shaped or

umbrella-shaped bodies Tetramerous symmetry (body parts

arranged in fours)

Mouth is usually centered on theconcave side

Tentacles extend from the rim of theumbrella


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Jellylike layer of mesoglia is thickerconsisting the bulk of the animal and

making it more buoyant

medusae arecommonly called jellyfishes


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Algae frequently live as mutuals intissues of cnidarians, notably in some

freshwater hydras and reef-buildingcorals.

The presence of algae in reef-buildingcorals limits the occurrence of coral reefsto relatively shallow, clear water wheresunlight is sufficient for photosyntheticrequirements of the algae


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Hydras as food for mollusc and flatworms

Live as commensals on shells and other

surface of host (sea anemones andcertain hydroids)

Economic value of reef

Reef provide substantial amounts of food forhuman (fish and other animals associatedwith reefs


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Includes:branching, plantlike hydroids

Flowerlike sea anemones Architects of the ocean floor- gorgonian

corals (sea whips, sea fans, etc)

Stony coralswhose thousand of years ofcalcareous housebuilding great reefs

and coral islands.


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Class Hydrozoa Hydra

Obelia

Goneonemus

Class Scyphozoa Jellyfishes

Class Anthozoa Sea anemone

Stony corals

Class Cubozoa

The basis of classification is the adult forms whether polyp or medusa.


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Fresh water members of this class livesingly, but the marine forms live singly or

form polymorphic colony. Though only polyp or medusa is found

but sometimes both polyp or medusamay be found in the same animal.

Gastrovascular cavity is directlyconnected with mouth.


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Alternation of generation is found in thelife cycle.

Ciliated planula larva is found. No stomodeum, velum present in

medusa.

Radial canals in medusa are notbranched.

Gametes develop from ectoderm.


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Kingdom Animalia

Phylum Cnidaria

Class Hydrozoa OrderHydroida

SuborderHydrida

Family Hydridae Genus Hydra

Species: Hydra vulgaris

http://animaldiversity.ummz.umich.edu
http://animaldiversity.ummz.umich.edu/site/accounts/pictures/Animalia.htmlhttp://animaldiversity.ummz.umich.edu/site/accounts/pictures/Cnidaria.htmlhttp://animaldiversity.ummz.umich.edu/site/accounts/pictures/Hydrozoa.htmlhttp://animaldiversity.ummz.umich.edu/site/accounts/pictures/Hydroida.htmlhttp://animaldiversity.ummz.umich.edu/site/accounts/pictures/Hydrida.htmlhttp://animaldiversity.ummz.umich.edu/site/accounts/pictures/Hydridae.htmlhttp://animaldiversity.ummz.umich.edu/http://animaldiversity.ummz.umich.edu/http://animaldiversity.ummz.umich.edu/site/accounts/pictures/Hydridae.htmlhttp://animaldiversity.ummz.umich.edu/site/accounts/pictures/Hydrida.htmlhttp://animaldiversity.ummz.umich.edu/site/accounts/pictures/Hydroida.htmlhttp://animaldiversity.ummz.umich.edu/site/accounts/pictures/Hydrozoa.htmlhttp://animaldiversity.ummz.umich.edu/site/accounts/pictures/Cnidaria.htmlhttp://animaldiversity.ummz.umich.edu/site/accounts/pictures/Animalia.html


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Kingdom Animalia (animals) Eumetazoa (metazoans)

Phylum Cnidaria (cnidarians)

Class Hydrozoa (hydralike animals,hydroids, and hydrozoans)

OrderHydroida (medusae)

SuborderHydrida

Family Hydridae Genus Hydra

Species Hydra utahensis
http://animaldiversity.ummz.umich.edu/site/accounts/classification/Animalia.htmlhttp://animaldiversity.ummz.umich.edu/site/accounts/classification/Eumetazoa.htmlhttp://animaldiversity.ummz.umich.edu/site/accounts/classification/Cnidaria.htmlhttp://animaldiversity.ummz.umich.edu/site/accounts/classification/Hydrozoa.htmlhttp://animaldiversity.ummz.umich.edu/site/accounts/classification/Hydroida.htmlhttp://animaldiversity.ummz.umich.edu/site/accounts/classification/Hydrida.htmlhttp://animaldiversity.ummz.umich.edu/site/accounts/classification/Hydridae.htmlhttp://animaldiversity.ummz.umich.edu/site/accounts/classification/Hydra.htmlhttp://animaldiversity.ummz.umich.edu/site/accounts/classification/Hydra.htmlhttp://animaldiversity.ummz.umich.edu/site/accounts/classification/Hydridae.htmlhttp://animaldiversity.ummz.umich.edu/site/accounts/classification/Hydrida.htmlhttp://animaldiversity.ummz.umich.edu/site/accounts/classification/Hydroida.htmlhttp://animaldiversity.ummz.umich.edu/site/accounts/classification/Hydroida.htmlhttp://animaldiversity.ummz.umich.edu/site/accounts/classification/Hydrozoa.htmlhttp://animaldiversity.ummz.umich.edu/site/accounts/classification/Hydrozoa.htmlhttp://animaldiversity.ummz.umich.edu/site/accounts/classification/Cnidaria.htmlhttp://animaldiversity.ummz.umich.edu/site/accounts/classification/Cnidaria.htmlhttp://animaldiversity.ummz.umich.edu/site/accounts/classification/Eumetazoa.htmlhttp://animaldiversity.ummz.umich.edu/site/accounts/classification/Eumetazoa.htmlhttp://animaldiversity.ummz.umich.edu/site/accounts/classification/Animalia.htmlhttp://animaldiversity.ummz.umich.edu/site/accounts/classification/Animalia.html


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Class Hydrozoa Order Hydroida

Suborder Anthomedusae

Freshwater species

Hydranths lack achitinous covering

With no medusa stage

Length up to 25-30 mm


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ZOOIDSMostly HYDRANTHS(Gastrozooids

feeding polyp

STALK

BASE (basal disc

or pedal)


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http://www.geochembio.com/biology/organisms/hydra/
http://www.geochembio.com/biology/organisms/hydra/http://www.geochembio.com/biology/organisms/hydra/


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Class Hydrozoa

Order Hydroida

Suborder Leptomedusae


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Dioecious

Gametes are fertilized in the water and thezygote develops into a planula larva whichsettles into substrate and metamorphose intocolony


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Kingdom: Animalia

Subkingdom: Eumetazoa

Phylum: Cnidaria Subphylum: Medusozoa

Class: Hydrozoa

Subclass: Leptolinae Order: Leptomedusae

Suborder: Proboscidoidea Family: Campanulariidae

Genus: ObeliaPeron and Lesueur, 1810

Species: Obelia dichotoma

Obelia geniculata Obelia longissima

Obelia bidentata

http://en.wikipedia.org/wiki/Obelia
http://en.wikipedia.org/wiki/Animalhttp://en.wikipedia.org/wiki/Eumetazoahttp://en.wikipedia.org/wiki/Cnidariahttp://en.wikipedia.org/wiki/Medusozoahttp://en.wikipedia.org/wiki/Hydrozoahttp://en.wikipedia.org/wiki/Leptolinaehttp://en.wikipedia.org/wiki/Leptomedusaehttp://en.wikipedia.org/w/index.php?title=Proboscidoidea&action=edit&redlink=1http://en.wikipedia.org/wiki/Campanulariidaehttp://en.wikipedia.org/wiki/Obeliahttp://en.wikipedia.org/wiki/Obeliahttp://en.wikipedia.org/wiki/Campanulariidaehttp://en.wikipedia.org/w/index.php?title=Proboscidoidea&action=edit&redlink=1http://en.wikipedia.org/wiki/Leptomedusaehttp://en.wikipedia.org/wiki/Leptolinaehttp://en.wikipedia.org/wiki/Hydrozoahttp://en.wikipedia.org/wiki/Medusozoahttp://en.wikipedia.org/wiki/Cnidariahttp://en.wikipedia.org/wiki/Eumetazoahttp://en.wikipedia.org/wiki/Animal


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The medusa of Gonionemus. hydrozoa

http://webs.lander.edu/rsfox/invertebrates/gonionemus.html
http://webs.lander.edu/rsfox/invertebrates/gonionemus.htmlhttp://webs.lander.edu/rsfox/invertebrates/gonionemus.html


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Anthozoans include

corals, sea anemones,sea pens, and seapansies.

These animals are eithersolitary or colonialpolyps that liveattached to a substrate(surface).

Of the 6,000 knownanthozoan species,corals comprise about

2,500 species.


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Sea anemones and corals have polypsand no medusae

Corals are colonial and secrete calciumcarbonate skeletons. Coral reefs are theaccumulation of these skeletons.


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The Class Anthozoa is further divided into three subclasses:Octocorallia, Zoantharia, and Tabulata (extinct colonialcorals).

Subclass Octocorallia. Polyps are characterized byhaving eightpinnate (side- branching) tentacles.Octocorallians include gorgonian corals, sea pens, seapansies, organ- pipe corals, and soft corals (orderAlcyonacea). Most are colonial.

Subclass Zoantharia. Polyps are characterized by havingtentacles in multiples of six. Zoantharian tentacles arerarely pinnate. Black corals and reef-building corals (orderScleractinia) are members of this subclass. Reef-buildingcorals are also known as "hard corals" or "stony corals".Zoantharians may be either solitary or colonial.


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Classification:

Kingdom Animalia (animals)Phylum Coelenterata (corals, jellyfish, sea anemoneshydroids)

Class Anthozoa meaning "flower-like animals"(corals and sea anemones)

Order Actiniaria.


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Diadumene dia


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The sea anemone is considered to be the flower

of the sea. Sea anemones look like plants, but

they are really meat-eating animals.

Sea anemones come in different sizes and many

different colors.The sea anemone can attach

itself to rocks or coral. In the center of the seaanemone is their mouth. In order for the sea

anemone to eat, they must wait for their food to

swim by. Then they sting it with their tentacles,

and then push it into their mouth.

Sea anemones spend most of their lives in one

place. They can attach themselves to rocks.

Some even bury themselves in the mud.


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Class AnthozoaSubclass Zoantharia (Hexacorallia)

OrderScleractiniaGenus Meandrina (Brain coral)

Genus Astrangia (Eyed coral)Genus Fungia (Mushroom coral)Genus Acropora (Staghorn, elkhorn, Antler coral)Genus Porites (reef coral)Genus Oculina


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This Class contains the largerjellyfishes,with some reaching two metres acrossthe bell and with tentacles 30 metres

long.

They are mainly marine and free floating,

though they can "swim" by pulsations ofthe bell. In this Class the polyp stage iseither reduced or absent. There arearound 215 species.


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Class Scyphozoa

Order Semaeostomeae

http://www.discoverlife.org/nh/tx/Cnidaria/Jellyfish/

Aurelia(Desor, 1848) Sea nettle

http://cas.bellarmine.edu/tietjen/AnimalDiversity/Lab4%20Porifera%20and%20Cnidaria.htm
http://www.discoverlife.org/nh/tx/Cnidaria/Jellyfish/http://www.discoverlife.org/20/q?search=Aureliahttp://cas.bellarmine.edu/tietjen/AnimalDiversity/Lab4%20Porifera%20and%20Cnidaria.htmhttp://cas.bellarmine.edu/tietjen/AnimalDiversity/Lab4%20Porifera%20and%20Cnidaria.htmhttp://cas.bellarmine.edu/tietjen/AnimalDiversity/Lab4%20Porifera%20and%20Cnidaria.htmhttp://cas.bellarmine.edu/tietjen/AnimalDiversity/Lab4%20Porifera%20and%20Cnidaria.htmhttp://www.discoverlife.org/20/q?search=Aureliahttp://www.discoverlife.org/nh/tx/Cnidaria/Jellyfish/


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Aurelia sp. is a typicalexample

The lappets come in pairs,and between them is a senseorgan called a rhopaliumcontaining a statocysts togive the animal information

on its equilibrium andorientation, sensory pits, and,in some species, ocelli (simpleeyes).


Aureliarhopallium,a multifunction sensory organ
http://cas.bellarmine.edu/tietjen/AnimalDiversity/Lab4%20Porifera%20and%20Cnidaria.htmhttp://cas.bellarmine.edu/tietjen/AnimalDiversity/Lab4%20Porifera%20and%20Cnidaria.htmhttp://cas.bellarmine.edu/tietjen/AnimalDiversity/Lab4%20Porifera%20and%20Cnidaria.htmhttp://cas.bellarmine.edu/tietjen/AnimalDiversity/Lab4%20Porifera%20and%20Cnidaria.htm


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The oral arms captureprey.

The tentacles are armedwith nematocysts (seeillustration on the right), asis the entire body surface.

Aurelia sp. has relativelyshort tentacles, and feedson plankton. The planktonis passed to the mouth bycilia.

http://cas.bellarmine.edu/tietjen/AnimalDiversity/Lab4%20Porifera%20and%20Cnidaria.htmhttp://cas.bellarmine.edu/tietjen/AnimalDiversity/Lab4%20Porifera%20and%20Cnidaria.htmhttp://cas.bellarmine.edu/tietjen/AnimalDiversity/Lab4%20Porifera%20and%20Cnidaria.htmhttp://cas.bellarmine.edu/tietjen/AnimalDiversity/Lab4%20Porifera%20and%20Cnidaria.htm


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Aurelia, early strobila stageAurelia, late strobila stage

http://cas.bellarmine.edu/tietjen/AnimalDiversity/Lab4%20Porifera%20and%20Cnidaria.htmhttp://cas.bellarmine.edu/tietjen/AnimalDiversity/Lab4%20Porifera%20and%20Cnidaria.htm


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Aurelia, ephyra stage (young medusa
http://cas.bellarmine.edu/tietjen/AnimalDiversity/Lab4%20Porifera%20and%20Cnidaria.htmhttp://cas.bellarmine.edu/tietjen/AnimalDiversity/Lab4%20Porifera%20and%20Cnidaria.htm


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Sea Nettle scientific classification:Kingdom: AnimaliaPhylum: CnidariaClass: Scyphozoa

Order: SemaeostomeaeFamily: PelagiidaeGenus: ChrysaoraSpecies: Chrysaora fuscescens

Pacific Sea Nettle (Chrysaora fuscescens), Montery BayAquarium

Dec 2009, Photo by Mark Leavitt


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The cubozoan body is shaped like a square bell, with themouth suspended inside it on a tube (the manubrium) thatleads upward to the stomach, which is inside the top part

of the bell. Extending around the inside bottom of the bellis a ring of tissue called the velarium, and at the bottomcorners of the bell are muscular fleshy pads (pedalia), withone or more tentacles connected to each pedalium. Foursensory structures called rhopalia are located near thecenter of each of the four sides of the bell. Box jellyfishhave eyes that are surprisingly complex, including regionswith lenses, corneas, and retinas; however, box jellyfish donot have a brain, so how the images are interpretedremains unknown. Like all cnidarians, box jellyfish possessstinging cells that can fire a barb and transfer venom(Waggoner and Collins 2000).
http://www.newworldencyclopedia.org/entry/Eyehttp://www.newworldencyclopedia.org/entry/Eyehttp://www.newworldencyclopedia.org/entry/Eye


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Cubozoans are agile and active swimmers, unlike themore planktonic jellyfish. They have been commonlyobserved to swim a meter in just five to ten seconds,and there are unconfirmed reports of largespecimens of Chironex fleckeri swimming as fast astwo meters in one second (Waggoner and Collins2000). The high speeds are achieved through a kindof squirting action in which the medusa contractswhile the velarium at the bottom contracts evenmore, producing a constricted opening through

which the water is forcefully expelled.

Box jellies can be found in many tropical areas,including nearAustralia, the Philippines, Hawaii,and Vietnam.
http://www.newworldencyclopedia.org/entry/Australiahttp://www.newworldencyclopedia.org/entry/Philippineshttp://www.newworldencyclopedia.org/entry/Hawaiihttp://www.newworldencyclopedia.org/entry/Vietnamhttp://www.newworldencyclopedia.org/entry/Australiahttp://www.newworldencyclopedia.org/entry/Philippineshttp://www.newworldencyclopedia.org/entry/Hawaiihttp://www.newworldencyclopedia.org/entry/Vietnamhttp://www.newworldencyclopedia.org/entry/Vietnamhttp://www.newworldencyclopedia.org/entry/Hawaiihttp://www.newworldencyclopedia.org/entry/Philippineshttp://www.newworldencyclopedia.org/entry/Australia


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Kingdom:AnimaliaPhylum:CnidariaClass:CubozoaWerner,1975Order:CubomedusaeHaeckel 1877
http://www.newworldencyclopedia.org/entry/Animalhttp://www.newworldencyclopedia.org/entry/Cnidariahttp://www.newworldencyclopedia.org/entry/Ernst_Haeckelhttp://www.newworldencyclopedia.org/entry/Ernst_Haeckelhttp://www.newworldencyclopedia.org/entry/Cnidariahttp://www.newworldencyclopedia.org/entry/Animal

Activity 3. Cnidarians

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