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Unit 5, Part 1: Phylums: Porifera, Cnidaria, Ctenophora
Phylum Porifera:
They are primarily marine animals
Made of loosely organized cells
There are about 9,000 species
Main Characteristics:
They are asymmetrical
Spongocoel: central cavity (branching chamber) through which water circulates
They have no tissues or organs
They have an Osculum: openings where water leaves out from
Cell types of Porifera:
Pinacocytes: cells that line the outer surface
Porocytes: openings where water entered and these cells regulate water circulation
Mesohyl: jellylike layer of cells that lies under pinacocytes
Mesenchyme cells: amoeboid cells that function for reproduction, transporting and storing food (they do not filter out food)
Choanocytes: (collar cells) that line the inner chamber and has flagellum that creates water currents and filters out food particles
Sponge Skeleton Makeup:
Spicules: needle like spikes
Spongin: fibrous material made of collagen
Body Forms:
Three Types of Body Forms
Ascon: vase like body form
Sycon: body form where walls appear folded
Leucon: body form with extensively branched canal system
Water Currents:
Water enters through the porocytes
The water then enters into the spongocoel where the choanocytes that line the walls whip their fagellum around to seperate the water from the food
The water exits out through the osculum
Maintenance Functions:
Sponges are filter feeders through choanocytes
Mesenchyme cells distribute food to the other cells of the sponge
Waste is eliminated through simple diffusion
Sponges have no nerve cells
Reproduction:
Monoecious: both sexes occur in the same individual
These sponges DO NOT self-fertilize
Sperm exits through the osculum and then enters another sponge through incurrent water
The fertilization then results in flagellated larvae
Asexual Reproduction: Gemmules
Gemmules are resistant capsules containing mesenchyme cells (amoebic cells)
These gemmules occur when conditions are unfavorable
These gemmules can then reorganize into a sponge
Classes of Porifera:
Class Calcarea:
Spicules of calcium carbonate
These sponges are responsible for the limestone in the ocean
Capable of all body forms
All marine
Class Hexactinella: “glass sponges”
Spicules of silica (glass)
Can have sycon or leucon body form
All marine
Class Demospongiae:
Brightly colored
Spicules or sponging (or both)
Only leucon body forms
Freshwater or marine
These are bath sponges
Class Homoscleromorpha
Simplest ones
Small or absent spicules
All marine
Phylum Cnidaria:
Main Characteristics:
Mostly marine
Over 9,000 species
Radial symmetry
Diploblastic; has only two germ layers
Body Wall:
Epidermis: outer layer of the body wall
Gastrodermis: inner layer of the body wall
Mesoglea: the jelly-like material between the epidermis and gastrodermis'
Cnidocytes:
These are stinging cells that are made of either gastrodermal or epidermal cells
Cnidocytes produce cnida
Cnida: fluid filled capsule containing coiled hollow tube
Nematocysts: type of cnida used in food gathering and defense (they deliver paralyzing toxin)
Reproduction: (Dioecious)
Alternation of generations: the life cycle of cnidarians includes both body forms
Polyp stage:
Usually asexual and sessile during this stage
Mouth is surrounded by tentacles and the aboral end is attached to substrate
Medusa stage:
Free swimming
Shaped like an inverted bowl
Mouth centrally located and facing down
Maintenance Functions:
Gastrovascular Cavity; digestions, exchange of gases and waste, discharge of gametes
Most eat small crustaceans or fish
Enzymes help digest in food vacuoles
“Skeleton”:
Hydrostatic Skeleton: water filled gastrovascular cavity contracts and causes movements as it propels itself
Polyps:
move through somersaulting and gliding along the substrate
Medusae:
move through swimming and floating
Nerve Cells:
Most primitive nerve cells in animal kingdom
Have no brain
Located below epidermis and form a nerve net
Conducts impulses around body in response to stimulus
Waste:
Large surface area to volume ratio
Waste is eliminated through diffusion
They only have one opening so waster is disposed through the mouth
Reproduction:
Cnidarians (jellyfish) are dioecious
Meaning that each individual has one sex (male or female)
Life Cycle:
After fertilization of and egg than a blastula is formed
This blastula matures into free swimming planula larva
The planula larvaa then settles on a substrate as a polyp
Medusa body stage forms from budding polyp
Classes of Cnidarians:
Class Hydrozoa:
Small, mostly marine
But, they do have some freshwater species
Some do not have a medusa stage
Can exist as colonial polyps through budding (diagram)
Gastrozooid: feeding polyp
Gonoozoid: reproductive polyp
Class Staurozoa:
All marine
Lack a medusa stage
Crawling planula larvae
Class Scyphozoa:
All marine
True “jellyfish”
Dominant medusa stage
Class Cubozoa:
Cube shaped medusa
Polyps are small
Active swimmers
Some are very dangerous
Class Anthozoa (Anemones):
Lack medusa
Solitary or colonial
Anemones, soft or stony corals
All marine
Phylum Ctenophora:
Comb jellies
Same basic characteristics as cnidarians
Bioluminescent
Comb Rows:
Rows of thousands of cillia that are used for motion
Colloblasts:
Cells used to capture prey
Unit 5, Part 1: Phylums: Porifera, Cnidaria, Ctenophora
Phylum Porifera:
They are primarily marine animals
Made of loosely organized cells
There are about 9,000 species
Main Characteristics:
They are asymmetrical
Spongocoel: central cavity (branching chamber) through which water circulates
They have no tissues or organs
They have an Osculum: openings where water leaves out from
Cell types of Porifera:
Pinacocytes: cells that line the outer surface
Porocytes: openings where water entered and these cells regulate water circulation
Mesohyl: jellylike layer of cells that lies under pinacocytes
Mesenchyme cells: amoeboid cells that function for reproduction, transporting and storing food (they do not filter out food)
Choanocytes: (collar cells) that line the inner chamber and has flagellum that creates water currents and filters out food particles
Sponge Skeleton Makeup:
Spicules: needle like spikes
Spongin: fibrous material made of collagen
Body Forms:
Three Types of Body Forms
Ascon: vase like body form
Sycon: body form where walls appear folded
Leucon: body form with extensively branched canal system
Water Currents:
Water enters through the porocytes
The water then enters into the spongocoel where the choanocytes that line the walls whip their fagellum around to seperate the water from the food
The water exits out through the osculum
Maintenance Functions:
Sponges are filter feeders through choanocytes
Mesenchyme cells distribute food to the other cells of the sponge
Waste is eliminated through simple diffusion
Sponges have no nerve cells
Reproduction:
Monoecious: both sexes occur in the same individual
These sponges DO NOT self-fertilize
Sperm exits through the osculum and then enters another sponge through incurrent water
The fertilization then results in flagellated larvae
Asexual Reproduction: Gemmules
Gemmules are resistant capsules containing mesenchyme cells (amoebic cells)
These gemmules occur when conditions are unfavorable
These gemmules can then reorganize into a sponge
Classes of Porifera:
Class Calcarea:
Spicules of calcium carbonate
These sponges are responsible for the limestone in the ocean
Capable of all body forms
All marine
Class Hexactinella: “glass sponges”
Spicules of silica (glass)
Can have sycon or leucon body form
All marine
Class Demospongiae:
Brightly colored
Spicules or sponging (or both)
Only leucon body forms
Freshwater or marine
These are bath sponges
Class Homoscleromorpha
Simplest ones
Small or absent spicules
All marine
Phylum Cnidaria:
Main Characteristics:
Mostly marine
Over 9,000 species
Radial symmetry
Diploblastic; has only two germ layers
Body Wall:
Epidermis: outer layer of the body wall
Gastrodermis: inner layer of the body wall
Mesoglea: the jelly-like material between the epidermis and gastrodermis'
Cnidocytes:
These are stinging cells that are made of either gastrodermal or epidermal cells
Cnidocytes produce cnida
Cnida: fluid filled capsule containing coiled hollow tube
Nematocysts: type of cnida used in food gathering and defense (they deliver paralyzing toxin)
Reproduction: (Dioecious)
Alternation of generations: the life cycle of cnidarians includes both body forms
Polyp stage:
Usually asexual and sessile during this stage
Mouth is surrounded by tentacles and the aboral end is attached to substrate
Medusa stage:
Free swimming
Shaped like an inverted bowl
Mouth centrally located and facing down
Maintenance Functions:
Gastrovascular Cavity; digestions, exchange of gases and waste, discharge of gametes
Most eat small crustaceans or fish
Enzymes help digest in food vacuoles
“Skeleton”:
Hydrostatic Skeleton: water filled gastrovascular cavity contracts and causes movements as it propels itself
Polyps:
move through somersaulting and gliding along the substrate
Medusae:
move through swimming and floating
Nerve Cells:
Most primitive nerve cells in animal kingdom
Have no brain
Located below epidermis and form a nerve net
Conducts impulses around body in response to stimulus
Waste:
Large surface area to volume ratio
Waste is eliminated through diffusion
They only have one opening so waster is disposed through the mouth
Reproduction:
Cnidarians (jellyfish) are dioecious
Meaning that each individual has one sex (male or female)
Life Cycle:
After fertilization of and egg than a blastula is formed
This blastula matures into free swimming planula larva
The planula larvaa then settles on a substrate as a polyp
Medusa body stage forms from budding polyp
Classes of Cnidarians:
Class Hydrozoa:
Small, mostly marine
But, they do have some freshwater species
Some do not have a medusa stage
Can exist as colonial polyps through budding (diagram)
Gastrozooid: feeding polyp
Gonoozoid: reproductive polyp
Class Staurozoa:
All marine
Lack a medusa stage
Crawling planula larvae
Class Scyphozoa:
All marine
True “jellyfish”
Dominant medusa stage
Class Cubozoa:
Cube shaped medusa
Polyps are small
Active swimmers
Some are very dangerous
Class Anthozoa (Anemones):
Lack medusa
Solitary or colonial
Anemones, soft or stony corals
All marine
Phylum Ctenophora:
Comb jellies
Same basic characteristics as cnidarians
Bioluminescent
Comb Rows:
Rows of thousands of cillia that are used for motion
Colloblasts:
Cells used to capture prey