Chapter 8 Sponges, Cnidarians, Comb Jellies, and Marine Worms Objectives • Describe the structure and function of sponge biology. • Understand the role sponges play in ecoystems. • Differentiate between Cnidarians and ctenophores • Describe how cnidarians capture food items and protect themselves from predators. Objectives • Describe the structure of marine worms. • Define and give examples of meiofauna. • Describe the body structure of polychaetes and explain how their form relates to their function. I. What Are Animals? • Animal characteristics: 1. multicellular – distinguishes them from bacteria and most protists 2. eukaryotic cells without cell walls – distinguishes them from bacteria, fungi, algae and plants 3. heterotrophs 4. motile - (with the exception of adult sponges) Marine Phyla 1. Porifera - sponges 2. Cnidaria – corals, anemones, jellies 3. Ctenophores – comb jellies 4. Platyhelminthes – flatworms, turbellaria 5. Nematoda – round worms 6. Mollusca – snails, clams, squid, octopus 7. Annelida – sea worm, tube worm 8. Arthropoda – lobster, crab and krill 9. Echinodermata – sea stars, sea urchins, sea cucumber 10. Chordates – tunicates, salps, fish, reptiles, birds, & marine mammals II. Sponges • Phylum Porifera • Basic characteristics: – simple – asymmetric – sessile—permanently attached to a solid surface – have many shapes, sizes and colors – approximately 5,000 species of sponges
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Chapter 8
Sponges, Cnidarians, Comb Jellies, and Marine Worms
Objectives
• Describe the structure and function of sponge biology.
• Understand the role sponges play in ecoystems.
• Differentiate between Cnidarians and ctenophores
• Describe how cnidarians capture food items and protect themselves from predators.
Objectives
• Describe the structure of marine worms.
• Define and give examples of meiofauna.
• Describe the body structure of polychaetes and explain how their form relates to their function.
I. What Are Animals?
• Animal characteristics:1. multicellular
– distinguishes them from bacteria and most protists
2. eukaryotic cells without cell walls– distinguishes them from bacteria, fungi,
algae and plants
3. heterotrophs4. motile - (with the exception of adult
• Body is built around a system of water canals–ostia—tiny holes or pores through which
water enters the sponge’s body–spongocoel—spacious cavity in the sponge–osculum—large opening through which
water exits from the spongocoel
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Sponge Structure and Function
• Lacking tissues, sponges have specialized cells– collar cells (choanocytes) use their flagella
to provide force for moving water through the sponge’s body
–pinacocytes provide an outer covering for the sponge
–archaeocytes—cells that resemble amoebas, and can move through the body• can assume any of the other cell forms, or
transport materials
Sponge Structure and Function
• Structural materials– spicules—skeletal elements that give
support to a sponge’s body, which are produced by specialized cells and composed of calcium carbonate, silica or spongin• spongin—a protein that forms flexible fibers
Sponge Structure and Function
• Sponge size and body form–Size
• limited by water circulation
–Body Form• asconoid—simplest form; tubular and always
small• syconoid—some folding of body-wall• leuconoid—many-chambered sponges with the
highest degree of folding
Sponge Structure and Function
• Nutrition and digestion– filter feeders – sponges are one of the few animals that
can capture particles 0.1 to 1.0 micrometers in size
Sponge Structure and Function
• Reproduction in sponges–asexual reproduction
• budding—a group of cells on the outer surface of the sponge develops and grows into a tiny new sponge, which drops off
• fragmentation—production of a new sponge from pieces that are broken off
– sexual reproduction• eggs usually develop from archaeocytes and
sperm from modified collar cells• larval stage is a planktonic
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Ecological Roles of Sponges• Competition
–compete for space to attach with corals and bryozoans
• Predator-prey relationships– few species eat sponges
• spicules are like needles• some produce chemical deterrents
*major food source for hawksbill sea turtles
Ecological Roles of Sponges
• Symbiotic relationships–sponges are mutualistic or commensalistic
hosts to many organisms• e.g. mutualistic bacteria
–many organisms live within the canals or spongocoel, for protection, water flow
Ecological Roles of Sponges
• Sponges and nutrient cycling–boring sponges recycle calcium as they
Sponges of New EnglandFinger Sponge (Haliclona oculata) –Short stalk with flat to rounded finger-shaped branches. Light brown, gray-brown, or purple in color. Found attached to rock habitat from low tide line to 400'. Grows to 18" high.
Red Beard Sponge (Microciona prolifera)- Short branching sponge with flattened branches. Differs from Finger Sponge in color – orange to red. Found on rock, pilings and other solid substrate. Grows up to 8" high. Subtidal depths.Bread Sponge (Halichondria parma) -
Encrusting sponge found on rock, pilings, etc. Colors vary from brown, orange, yellow and green. Occurs in many shapes, but normally has cone-shaped bulges. Can grow to several feet in diameter. Can be difficult to identify. Intertidal to 200'.
Common Palmate Sponge (Isodictyapalmata) - Sponge with more flattened than rounded branches. Holes (oscula) in sponge are very obvious - more so than any other branching sponge in the region. Grows to 12" high. Color yellow, brown to orange. Found sub-tidally.
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II. Cnidarians: Animals with Stinging Cells
• Phylum Cnidaria• Named for their cnidocytes—stinging
cells• Cnidocytes are used to capture prey
and protect the animal
A. Organization
• 1. Radial symmetry• 2. Often exhibit 2 body plans within
their life cycles:–a. polyp—a benthic form characterized by
a cylindrical body with an opening at 1 end
–b. medusa—a free-floating stage (jellyfish)
B. Stinging Cells
• 1. Cnida—stinging organelle within a cnidocyte–Used for prey capture & defense