Porifera (Sponges),

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Chapter 33

• Porifera (Sponges),
• Cnidarians (hydra, jellyfish, sea anemone, some
  corals)
• Ctenophores ( comb jellies)

pictures from http//www.bio.miami.edu/dana/160
/160S06_14.html http//sps.k12.ar.us/massengale/
images/brac-sponges-21.jpg
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SPONGES
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Why are sponges considered animals?

• Early biologists thought they were plants.
• BUT- Have 2 key characteristics of animals
• Heterotrophic
• Multicellular
• (Reproduction is asexual or sexual)
• (Mobility- adults are sessile- but some species
  can move up to 4mm/day larvae have flagella.)
• Represent transition from unicellular to
  multicellular life.

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Phylum Porifera

• Invertebrate (no backbone)
• Asymmetrical
• No true tissues or organs
• All species -Aquatic
• Adult is Sessile (attach to surface, do not move)

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B. Digestive System/Wastes

• 1. Filter Feeding- bits of organic matter or
  bacteria
• 2. Amoebocytes- crawling cells that deliver
  nutrients from choanocytes to the rest of the
  body
• 3. Digestion is Intracellular
• -wastes CO2 expelled with water as it passes
  through osculum

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• Choanocytes in the interior layer draw water
  through the ostia that penetrate the body wall.
• The water leaves through the osculum.

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A simple Sponge
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Sponge Skeleton

• 2 types support- (different sponges use one or
  both)
• Spongin - tough, flexible protein fibers
• or
• Spicules hard calcium carbonate (like in
  limestone, teeth bones) or hard silicon dioxide
  (quartz, glass)

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C. Reproductive System

• Sponges can reproduce asexually and sexually
• 1. Asexual
• a. Budding- part of the parent pinches off
  forms a new organism
• b. Gemmules a reproductive structure in
  sponges,
• -produced in harsh conditions
• -a food-filled ball of amoebocytes in a
  protective coat
• c. Regeneration- regrowth of missing cells.

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Sexually

• Joining of egg and sperm
• Hermaphrodite- each sponge has both eggs sperm

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Sexual Reproduction
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Phylum Cnidaria

• Radially symmetrical
• More complex than sponges
• Have tissues and few simple organs
• (Hydra, Jellyfish, Sea Anemones, some corals)

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2 Body Forms

• Polyp
• vase-shaped,
• Sessile
• Hydra, sea anemone

• Medusa
• bell shaped,
• Free swimming
• Jellyfish

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• POLYP
• MEDUSA

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4 Groups

• Class Hydrozoa
• This class includes Obelia, man-o-war, and the
  hydra.
• Hydrozoans may live as polyps, medusae, or mixed
  colonies.
• Class Cubozoa
• This class includes box jellies.
• Cubozoans spend most of their lives as medusae.

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Obelia
Hydra
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• Class Scyphozoa
• This class includes jellyfish.
• Scyphozoans spend most of their lives as medusae.
• Class Anthozoa
• This class includes sea anemones and corals.
• Anthozoans live only as polyps.

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Jellyfish
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Sea anemone
Coral
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• Most live individually except hydra coral
• Coral live in colony of polyps
• Most live in salt water except for Hydra

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Digestive System/Waste

• Cnidocytes (special defensive cell) have
  Nematocysts (coiled organelle with stinging
  filament)
• Tentacles push
• prey through mouth
• into gastrointestinal cavity
• Digestion is
• Extracellular, wastes
• expelled through mouth.

http//www.emc.maricopa.edu/faculty/farabee/biobk/
cnidaria_1.gif
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Nervous System

• Nerve Net -Nerve cells located below epidermis
  near the mesoglea interconnect and form a nerve
  net throughout the body.
• Cnidarians have both muscle fibers and nerve
  fibers, making these animals capable of
  directional movement.
• 2. Movement using pulsing tentacles

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Reproductive Systems-

• Some reproduce asexually (see Hydra-budding)
  especially in warmer temperatures.
• Sexual reproduction-
• lower temps
• hermaphrodites.
• Motile sperm, egg in ovary.

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Medusa

• Can reproduce either sexually or asexually
• Sexually
• Fertilized eggs become larva
• Larva settle and form polyp
• Asexually
• Young medusa bud and break off

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Reproduction in Aurelia (jellyfish)
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Polyps

• Asexually- buds fall of the parents
• Sexually- egg and sperm

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D. Classes

• 1QUESTIONS
• Use your book to describe one organism from each
  of the 4 classes.
• List diagram the steps in describing the
  cnidarian hunting feeding process (use terms
  for special parts.)

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III. Ctenophora (100 species)

• Ctenophora means comb holder- named for the 8
  comb-like rows of cilia that run along outside of
  these animals
• How are they different than jellyfish?
• A. Movement - beating cilia

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B. Digestive

• -ctenophores are voracious predators.
• -Unlike cnidarians, they lack stinging cells. (no
  cnidocytes)
• -Instead,to capture prey, have sticky cells
  called colloblasts. located on ends of 2
  tentacles.
• -In a few species, special cilia in the mouth are
  used for biting gelatinous prey.

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• Nervous- have an apical organ for sensing
  environment.
• D. Bioluminescence glow with light they produce
  with chemicals

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• Most are hermaphroditic
• Often called comb jellies