Phylum Cnidaria

What happens during fertilization and its growth into a polyp

After the egg is fertilized, a zygote grows and blastula develops, becoming a free-swimming larva that swims until it attaches to a surface to grow into a polyp

What is the advantage of a motile form in the life cycle of many cnidarians?

Allows the organism to get away from predators and can move to places that have an abundance of food. A motile form allows them to go get their food than waiting for it in a sessile form

Reefs that encircle a lagoon but not an island

Atolls

Runs parallel to shore and has a wider and deeper lagoon

Barrier Reef

Only tube anemones and thorny corals

Ceriantipatharia

All marine; occurs in deep and shallow water and in polar seas as well as tropical seas

Class Anthozoa

Many forms are supported by skeletons

Class Anthozoa

Polyps have a flowerlike appearance

Class Anthozoa

There is no medusa stage

Class Anthozoa

In transverse section the bells are almost square; a tentacle or group of tentacles is found at the corner of each square

Class Cubozoa

Medusoid is the predominant form, polypoid is inconspicuous and in most cases unknown

Class Cubozoa

Majority are marine and colonial in form

Class Hydrozoa

Typical life cycle includes both an asexual polyp and a sexual medusa stage

Class Hydrozoa

Class includes most of the larger jellyfishes; movement is by rhythmical pulsations of the bell

Class Scyphozoa

Life cycle does not contain a medusa phase; the top of the polyp resembles a medusa

Class Staurozoa

What forms by budding during asexual reproduction?

Clones or colonies

The most productive of all ecosystems?

Coral Reefs

All cnidarian forms fit into one of two morphological types: a polyp or a medusa

Dimorphism

The presence of both polyp and medusa body forms in one life cycle is called ________.

Dimorphism

List and describe at least three ecological roles of members of the Phylum Cnidaria

Ecological roles: coral reefs houses many species Jellyfish are predators in the food web and are also prey for a lot of species (keep it in order) Sea anemones provide a place for fish to hide The organisms are a vital part of the aquatic community

Muscular contractions via?

Epitheliomuscular cells

True or False: Asymmetry exists in this phylum

False; radial symmetry and biracial symmetry only exists

Elimination: of undigested food wastes

Food wastes are eliminated through the mouth since the jellyfish does not have an anus (the jelly fish can't do anything with it)

Close to a landmass with either no lagoon or a narrow lagoon between reef and shore

Fringing Reefs

eight pinnate tentacles and eight unpaired, complete septa

Have octamerous symmetry

Sea anemones, hard corals

Hexacorallia (or Zoantharia)

Called true or stony corals

Hexacorallian Corals

Just like a sea anemone's, a coral polyp's gastrovascular cavity is subdivided by septa arranged in multiples of six

Hexacorallian Corals

No pedal disc, the epidermis at the base of the column secretes a limy skeleton cup

Hexacorallian Corals

In Class Cubozoa, the stings of some species can be fatal to who?

Humans

The fertilization of the egg cells occur where?

In the water

An example of a medusa body form is a _________.

Jellyfish

Sexual Reproduction: reproduction using gametes

Jellyfish are either male or female. In the medusa form, eggs and sperm are produced. The males release their sperm into the water and the female takes in the sperm. The sperm then fertilizes the egg. After fertilization of the egg, it becomes a free swimming planula larvae that goes off on its own

Asexual Reproduction: reproduction without using gametes

Jellyfish have two different body forms - the medusa and the polyp. During the polyp form, jellyfish can reproduce asexually by a process called budding.

Motility

Jellyfish move by a rhythmical pulsation. They squeeze their bodies in order to move themselves forward

Jellyfish Form- floating or free swimming, bell or umbrella shaped body, symmetry where body parts are arranged in fours, tentacles extend outward from the rim of the umbrella

Medusa

What is the dominant stage of the cnidarian shown in the transparency?

Medusa

Explain the evolutionary significance of the multicellular life form of members of the phylum cnidaria

Members of the phylum cnidaria are significant to evolution when compared to unicellular forms because multicellular life forms had to evolve and be dependent upon other cells. Multicellular organisms are also more specialized unlike unicellular life forms

What lies between the two body layers?

Mesoglea

The medusa is free-swimming and is therefore described as _________.

Motile

Cnidocytes present the house stinging organelles called?

Nematocysts

Circulation: transporting nutrients to all of its cells

Nutrients are transported to different cells by the canals. Nutrients can be easily absorbed since the layers of covering are so thin

Contains soft and thorny corals, such as sea pens, sea pansies and others

Octocorallia (or Alcyonaria)

Respiration: taking in of oxygen and getting rid of carbon dioxide

Oxygen diffuses into their cells because their outer layer and inner layer are so thin. The oxygen is stored in the mesoglea. Just how oxygen can pass from the water into their cells, carbon dioxide passes out the jellyfish the same way

Hydroid Form- sedentary or sessile, tubular bodies, mouth surrounded by tentacles, and may reproduce asexually by budding or fission

Polyps

Reproduction in Polyps

Reproduction occurs of growing buds that will become medusae. The buds that grow build up, eventually leaving the parent polyp and the cycle starts again

In the Class Cubozoa, __________ are present, each housing six eyes in addition to other sense organs

Rhopalia

Asexual reproduction commonly occurs by pedal laceration

Sea Anemones

Carnivorous

Sea Anemones

Cylindrical in form with tentacles arranged around the mouth of the flat oral disc

Sea Anemones

Polyps are larger and heavier than hydrozoan polyps

Sea Anemones

Sexes are separate in some, whereas others are hermaphroditic

Sea Anemones

Slit shape mouth leads into the pharynx --> gastrovascular cavity that is dived into six radial chambers by six pairs of primary septa

Sea Anemones

The polyp normally remains fixed to one place and is therefore described as _________.

Sessile

Gastrovascular cavities of the polyps communicate through a system of gastrodermal tubes called?

Solenia

What do sense organs include?

Statocysts (organs of balance) and ocelli (photosensitive organs)

Ingestion: Taking in food (Typical Jellyfish)

The cnidacyl is triggered and the thread shoots out into the organism to make it immobile so the jellyfish's tentacles can pull the prey into its mouth

Nervous System: coordinating movement and responding to stimuli

The coordination of a jellyfish is controlled by the nerve net, which are nerves located in the epidermis. Jellyfish also detect and respond to stimuli by the nerve net

Excretion: of metabolic wastes

The metabolic wastes of a jellyfish is excreted through the mouth since it has an incomplete gut (no anus). Every metabolic waste is passed through the mouth

Where do the tentacles encircle?

The mouth or oral region

Colonial and attach to firm substratum. Their skeleton is of a thorny material and has thorns

Thorny or black corals

True of False: Living polyps can retract into the safety of their cup when not feeding

True

True or False: Entirely aquatic (mostly marine)

True

Members of subclass Ceriantipatharia

Tube Anemones and Thorny Corals

Solitary and live buried up to level of oral disc in the sand

Tube anemones

Have unpaired septa

Tube anemones and Thorny Corals

Body form during the polyp stage

Tubular Body

Adult body is what?

Two layered (diploblastic)

Digestions: Breaking down its food into usable nutrients

When food enters the mouth, it then goes into the stomach and canals of the gastrovascular cavity, where it will be digested. Digestive enzymes are released from the cells that line the inner body cavity that break down the food

The polyp body from is generally responsible for ___________ reproduction.

asexual

Body form during the medusa stage

bell shape

The most important organisms that precipitate calcium carbonate to form reefs are?

hermatypic corals and corralling algae

An example of a cnidarians with a polyp body form is ________.

hydra

The polyp stage produces the _________ stage, which in turn produces the gametes - __________ and _________.

medusa, sperm, egg

Symmetrical and asymmetrical synapses

nerve net

Motility during the medusa stage

non sessile

In the Class Cubozoa, the base of each tentacle is differentiated into a flattened, tough blade called a _______.

pedalium

What are the two types of individuals?

polyps and medusae

Motility during the polyp stage

sessile

The medusa body form is responsible for ____________ reproduction.

sexual

A cnidarian ______ level of organization with _______ germ (cell) layers called the _________ and the _______.

tissue, 2, ectoderm, endoderm

Function of cnidarian structure is:

when an organism swims by the trigger (receives chemical and mechanical stimulation from prey) a thread shoots out into the prey to paralyze it or make is immobile. This allows the tentacles to bring the organism into the mouth and then into the gastrovascular cavity