Sponges, Cnidarians, and Ctenophores Chapter 33. Phylum Porifera Section 33.1.
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Transcript of Sponges, Cnidarians, and Ctenophores Chapter 33. Phylum Porifera Section 33.1.
Phylum PoriferaSection 33.1
Phylum Porifera
Latin for “Pore-Bearing”
Asymmetric Body Structure
Sponges
• Aquatic animals• Represent transition from
unicellular to multicellular life• No true tissue or organs
• 5,000 species (most marine)• Various colors, shapes, sizes, etc.
• Adults are sessile
Sponge Body Plan:
• Two layers of cells separated by mesohyl (jellylike substance)
• Body wall forms a hollow cylinder that is open at the top
More Sponge Parts:
• Choanocytes (collar cells): flagellated cells that draw water into the sponge
• Ostia (pores): pores that penetrate the body wall that allow water into the sponge
• Osculum: opening at the top of the sponge
Sponge Support System
• Simple skeleton made up of spongin and/or spicules• Spongin: tough, flexible protein fibers• Spicules: tiny, hard particles of calcium
carbonate or silicon dioxide• shaped like spikes
Spongin
Spicules
Sponge Anatomy
Feeding & Digestion
Filter feeders of plankton and other small organisms
Steps in feeding & digestion:1. Choanocytes beat & draw water into ostia
• Then collect food from water2. Nutrients pass from choanocytes to
amoebocytes • Crawling cells that deliver nutrients to rest
of the body3. Wastes and CO2 diffuse into the water and
goes out the osculumvideo
Water Flow:
Asexual Reproduction
• Regeneration: • regrowth of missing cells
• Budding:• sometimes the bud breaks off the parent
and becomes a new organism • or it may remain attached to the parent
and develop into a sponge colony
Environment gone bad?
Gemmules: food filled ball of amebocytes protected by protein & spicules• Can survive harsh conditions• Similar to endospore of bacteria
Sexual Reproduction
1. Sperm of one sponge enters pores of a different sponge
2. Choanocytes engulf the sperm3. Sperm transferred to ameobcytes4. Then transferred to egg in mesohyl5. Egg is fertilized6. Swimming larva leaves the
sponge and settles on an object to become an adult
Hermaphrodites
• Why doesn’t self-fertilization usually occur in an hermaphroditic species?
• Answer:• Less genetic diversity thus less of a
change to survive an environmental change (evolution would not occur as much)
Phyla Notecards:
• First side:• Phylum name• Example organisms• Drawing of organism
• With color!
• Opposite side:• Body symmetry• Mobility (adult & larval
stages)• Feeding methods• Reproductive methods• Defense mechanisms• Environment/habitat
Cnidaria & CtenophoraSection 33.2
Phylum Cnidaria
General Characteristics:
• Radial symmetry• Have tissues and simple organs• Aquatic (mostly marine)
Phylum Cnidaria
Body Plans:
• Medusa: bell-shaped specialized for swimming
• Polyp: vase-shaped specialized for sessile living
More Body Parts:
• Two cell layers:•Epidermis: outer
layer•Gastrodermis:
inner layer
• Mesoglea: • jellylike material
between two layers
Continued…
• Gastrovascular cavity: center of body with a hollow gut and mouth
• Tentacles: flexible extensions surrounding the mouth• Moves food in
Feeding & Defense:
• Cnidocytes: specialized cells used for defense and capturing prey• Gives the phylum its name!
• Nematocyst: organelle within cnidocyte with a long filament and a poison tip• Trigger response
Video
Nervous System:
• Nerve net: diffused web of interconnected nerve cells• No brain• No cephalization
• Can respond to stimuli • Nerve net contractile cell contraction of
whole body
• Can control swimming & feeding
Classification:
Four classes:
1. Class Hydrozoa2. Class Cubozoa
3. Class Scyphozoa4. Class Anthozoa
Class Hydrozoa:
• Colonial organisms (combo of polyp & medusa form)• Each organism has a specialized function for the
colony
• Exception: hydras – only polyps, NOT colonial
• Examples: Portuguese man-of-war, hydra, and Obelia
Video
Class Cubozoa:
• Commonly known as box jellies• Cube shaped medusa
• Some have cnidocytes that can cause death to humans• Example: Sea wasps
Class Scyphozoa:
• Commonly known as jellyfish• The medusa form is dominant• Some have poisonous nemotocytes
that can cause pain and death
• Biotechnology with Jellies video
Class Anthozoa:
• Meaning: flower animals• Dominant form = polyp• Examples: coral & sea anemone
• Some have symbiotic relationships with other species:• Coral with algae• Sea anemone with clownfish
Nemo!
Coral And Algae
Phylum Ctenophora
Distinguishing Characteristics:
• Meaning: comb holder• Commonly called comb jellies
• Move by beating cilia
• Contain colloblasts that secrete a sticky substance that blinds prey• Do not have cnidocytes (like other jellies)
Continued…
• Apical organ: sensory structure that determines orientation in the water
• Bioluminescence: production of light through chemical reactions
Phyla Notecards:
• First side:• Phylum name• Example organisms• Drawing of organism
• With color!
• Opposite side:• Body symmetry• Mobility (adult & larval
stages)• Feeding methods• Reproductive methods• Defense mechanisms• Environment/habitat
Class Notecards:
• First side:• Class name• Example organisms• Drawing of organism
• With color!
• Opposite side:• Unique characteristics• Description of
representative organism • Info about an organism
listed in the book
• Environment/habitat