Chapter 9 Phylum Cnidaria

Class Scyphozoa

"True jellies" that have rhopalia which house chemoreceptors, statocysts, and maybe ocelli (Subclass Scyphomedusae)

Class Anthozoa Subclass Hexacorallia Order Actiniaria

-Attach to substrate with pedal disc, which can help them move; -feeding behavior often chemically controlled and may induce bending of tentacle toward mouth or swallowing

Phylum Ctenophora

-Biradial symmetry with no head, but oral-aboral axis present -Most monoecious and free swimming larva develop gradually into adult, no metamorphosis ex. Pleurobrachia-2 tentacles trail in water catching passing prey with epidermal glue cells

Class Anthozoa Subclass Octocorallian

-Colonial, wiith gastrovascular cavities that communicate through a system of gastrodermal tubes that run through mesoglea -Limy spicules, fused spicules, or horny proteins

Phylum Ctenophora

-Comb jellies; 8 rows of comblike plates of cilia -Marine and primarily found in warmer waters; most free swimming, yet are at the mercy of tides and strong currents -May swim to deep water to avoid storms

Hexacorallia mutualisic relationships

-Dinoflagellates within tissues -crabs hold anemone against shell until anemone is attached ex. Damselfishes (anemone fish) Mucus on skin keeps anemone's nematocysts from firing

Class Anthozoa Subclass Hexacorallia Order Actiniaria

-Sea anemones found in coastal areas, especially in warmer waters -Separate sexes or hermaphroditic; monoecious species are protandrous (sperm first, then egg) -Asexual reproduction via pedal laceration or longitudinal fission

Class Staurozoa

-Stauromedusans are the only extant species -No polyp phase, is attached to medusa and undergoes sexual reproduction

Class Cubozoa

-They are strong swimmers and are medusa predominant (polyp inconspicuous or even unknown) -The base of each tentacle is flattened into a tough blade that is usually 2-3cm and almost square-shaped in section -cube or box jellies

Class Anthozoa Subclass Ceriantharia

-Tube anemones found in warmer waters that are solitary and burrow to oral disk in soft sediment -Produce tubes of secreted mucus and threads of nematocyst-like organelles that withdraw into tubes for protection

Class Scyphozoa: Cassiopeia

-Typically on its back, known as the upside down jelly and have a symbiotic relationship with dinoflagellates -No tentacles on umbrella margin or oral arm

cnidocytes

-cells that penetrate prey, inject toxin, entangle prey, or secrete adhesive substance -They have organelles called cnidae -Once cnida discharged, these are absorbed and replaced

Hydra reproduction

Asexual and sexual; most dioecious

coral bleaching

Becoming more of a problem with increasing ocean temperatures as heat damages part of the photosynthetic mechanism, so buildup of harmful oxidants cause Zooxanthellae to die or be expelled

Stomphia (sea anemone)

Class Anthozoa: Subclass Hexacorallia; move when sense touch of sea star and from liquids from star

mouth => stomach => radial canals => ring canal => tentacles

Class Hydrozoa food path

Scyphomedusae

Class Scyphozoa, is a subclass of medusoid Cnidarians whose manubrium often has four frilly oral arms for capturing and ingesting prey, no velum

medusae

Cnidarian body forms that often have tetramerous symmetry and have statocysts and ocelli

hydranths or gastrozooids

Cnidarian feeding polyps

budding, fission, or pedal laceration

Cnidarian polyp reproduction

budding and pedal laceration

Cnidarian polyps may reproduce by which of the following? Mark all that apply. a) sexual b) budding c) pedal laceration d) meiosis

gonangia or gonozooids

Cnidarian reproductive polyps

ocelli

Cnidarian sensory structures for light reception in medusae body forms

statocysts

Cnidarian sensory structures for orientation in medusae body forms

Class Scyphozoa: Aurelia

Common life cycle throughout Scyphozoa; a few species larva develop directly into medusa, no polyp

Zooxanthellae

Forms an endosymbiotic relationship with corals and performs photosynthesis.

Class Hydrozoa: Hydra

Freshwater hydrozoan found on underside of aquatic leaves and lily pads

Cnidarian hydrostatic skeleton

Gastrovascular cavity acts as this; most body support comes from buoyancy of water

Class Anthozoa Subclass Hexacorallia Order Scleractinia

Hard (stony) corals that secrete calcareous cup, have no pedal disc and can retract into cup for safety

green hydras

Have symbiotic relationship with green algae in gastrodermal cells

Hydra development

Holoblastic cleavage of zygote to form blastula; cysts form around embryos for winter survival

Class Hydrozoa

Hydroids, hydrocorals (fire corals), Portugese man-of-war (Physalia)

pneumatophore

Hypothesized to be from original larval polyp with gas inside similar to air

Class Hydrozoa

Most are marine and colonial with asexual polyp and sexual medusa; medusae may remain attached to colony or be absent; the gametes are shed by gonophores if medusae is absent; free swimming planula larvae

damselfish (anemone fish)

Mucus on skin keeps anemone's nematocysts from firing

Class Scyphozoa Rhizostoma

No tentacles on umbrella margin or oral arm

Phylum Cnidaria characteristics

Organization: tissue level, diploblastic Symmetry: generally radial, also biradial and tetramerous Digestion: extracellular, incomplete digestive tract Excretion: diffusion Respiration: diffusion Nervous System: nerve net Skeleton: hydrostatic skeleton Reproduction: asexual and sexual Larva: planula

aquatic, mostly marine

Phylum Cnidaria is found in which kind of environment?

Cnidarian nerve net

Plexus of nerve cells at base of epidermis and gastrodermis that has axons, synapses, sensory cells or effector organs, neurotransmitters; Aids in swimming movements, pulsation rate, and tentacle movement

coral reefs

Produced primarily by Scleractian, reef-building corals and coralline algae

Class Anthozoa

Sea anemones ,tube anemones, hard (stony) corals, horny corals, soft corals

Class Hydrozoa: Hydrocorals

Secrete calcareous skeletons and resemble true corals (fire coral)

Subclass Octocorallia

Soft and horny corals, including sea fans, sea pens, and sea

Physalia

Tentacles are zooids which are single animals in a colony, and has a pneumatophore which is the float

d) brain

The Cnidarian nervous system includes all of the following EXCEPT? a) sensory cells b) axons c) neurotransmitters d) brain

Class Anthozoa Subclass Hexacorallia Order Antipitharia

Thorny or black corals that are colonial and are attached to a firm substrate; has horny skeleton with thorns; few species and found in warmer waters

True

True or False: Cnidae are organelles found within cnidocytes that aid in prey capture.

False

True or False: Cnidarians are most closely related to the Ecdysozoans.

True

True or False: In addition to digestion, the gastrovascular cavity of Cnidarians acts as a hydrostatic skeleton.

False

True or False: Medusa are the sedentary body form found in the Cnidarian life cycle.

False

True or False: The mesoglea is the outer body of Cnidarians and its cells can differentiate into a variety of cell types.

Subclass Cerianthaparia

Tube anemones and horny corals; are hexamerous

tempuerature, light exposure, salinity

What 3 abiotic factors are important for coral reefs?

Hydrozoa, Scyphozoa, Anthozoa, Cubozoa

What are the 4 classes of Phylum Cnidaria?

Scleractinia and Antipitharia

What are the Orders in Subclass Hexacorallia?

Hexacorallia, Cerianthaparia, Octocorallia

What are the three subclasses of Class Anthozoa?

on the outer layer

Where are the living organisms in coral reefs?

d) Anthozoa

Which of the following Cnidarian Classes includes the sea anemones and stony corals? a) Scyphozoa b) Cubozoa c) Hydrozoa d) Anthozoa

b) hydrostatic skeleton

Which of the following is a CORRECT characteristic of Cnidarians? a) bilaterally symmetrical b) hydrostatic skeleton c) respiration via a swim bladder d) triploblastic

d) intracellular digestion with a complete digestive tract

Which of the following is an INCORRECT characteristic of Cnidarians? a) diploblastic b) excretion by diffusion c) nerve net d) intracellular digestion with a complete digestive tract

nematocyst

a type of cnida covered by an operculum and used to inject toxin for prey capture and defense; may have triggerlike cnidocil

pedal laceration

asexual reproduction in which a piece of the pedal disk develops into a new polyp

Cnidarian polyps

body form that is sedentary or sessile; produce other _______ or medusa asexually

epidermis and gastrodermis

cells of _______ and ________ differentiate into various cell types for protection, food gathering, movement, digestion, and absorption in Cnidarians

Class Anthozoa

class that is solitary or colonial with no medusa stage

Hydrozoa gastrovascular cavity

continuous from mouth to tentacles

Cnidarian body wall

epidermis, mesoglea, gastrodermis

Cnidarian medusa

floating or free-swimming life that reproduce asexually or sexually and are dioecious; some life cycles lack this body form.

gastrovascular cavity

found in Phylum Cnidaria and functions in digestion, respiration, excretion, and reproduction (release of gametes)

gastrodermis

functions mainly in digestion for Cnidarians

mesoglea

gelatinous, acts as a type of elastic skeleton for Cnidarians

Cnidarian polyp colonies

may have morphologically distinct polyps for feeding (hydranths or gastrozooids), reproductive (gonangia or gonozooids), or defense

Cnidarian polyp buds

may or may not detach from parent

Hydromedusae

mouth extended at end (manubrium)

Plerurobrachia

organism in Phylum Ctenophora with 2 tentacles that trail in the water catching passing prey with epidermal glue cells

epidermis

outer layer of Cnidarian body wall

Class Hydrozoa: Physalia

portugese man-of-war

Class Anthozoa Subclass Hexacorallia

sea anemones and hard corals; are hexamerous

rhopalia

sensory stuctures in Class Scyphozoa that house chemoreceptors, statocysts and maybe ocelli

nematocytes

specialized organelles within cnidocytes that eject a stinging thread

Aurelia life cycle

zygote develops on arms of female-> ciliated planula larvae->planula settles ->early strobila->strobila-> ephyra-> medusa