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