Chapter 33 Porifera (Sponges), Cnidarians (hydra, jellyfish, sea anemone, some corals) Ctenophores (...
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Transcript of Chapter 33 Porifera (Sponges), Cnidarians (hydra, jellyfish, sea anemone, some corals) Ctenophores (...
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
Animalia: A Progression of Complexity• As we begin discussing the animal kingdom-Consider
that as animal phyla diverge, organs and organ systems are added, increasing complexity.– Tissues ( # germ layers) – Body symmetry – Internal body cavity – Organs and Organ systems:
• integumentary system - protection (injury, infection, water loss) • digestive system - food processing • nervous system - coordination; response to environment• reproductive system – asexual or sexual, external or internal• excretory system - removal nitrogenous waste from body fluid • skeletal system - structural support • circulatory system - internal distribution of materials • respiratory system - gas exchange (O2 in, CO2 our)
Noted from: http://www.bio.miami.edu/dana/160/160S06_14.html
I. Porifera
• Invertebrate (no backbone)
• Asymmetrical
• No true tissues or organs
• No gastrula stage (embryonic development)
• Less cell specialization than other animals
• All species -Aquatic
• Adult is Sessile (attach to surface, do not move)
http://sps.k12.ar.us/massengale/images/brac-sponges-21.jpg
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 (http://www.ucmp.berkeley.edu/porifera/poriferalh.html) *larvae have flagella.)
• Represent transition from unicellular to multicellular life.
A. Basic Body plan of a Sponge
1. Asymmetrical2. Sessile3. Vocabulary of sponge parts:• Hollow cylinder shape, closed at bottom, opening
at top called Osculum.• Interior lined with Choanocytes – flagellated
cells that draw water into the sponge through pores in the body wall called Ostia.
• 2 layers of cells separated by mesohyl (a jelly like substance)
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)
Picture from: http://www-biol.paisley.ac.uk/biomedia/graphics/jpegs/SPICULES.gif
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
C. Reproductive System1. 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.
2. Sexuala. Sperm are released into water, enters next sponge through pores, choanocytes engulf sperm. Carry to ameobocytes, carry them to egg in mesophyl. Produces a flagellated Larvae (immature form)
b. Hermaphrodite- each sponge has both eggs & sperm
II. Cnidaria (Hydra, Jellyfish, Sea Anemones, some corals)
A. Body Plan1. Stages:
Medusa –bell shaped, swims
Polyp – vase-shaped, sessile2. 2 cell tissue layers-
Epidermis outside layer
Gastrodermis inside layer
-with Mesoglea in between)3. Gastrovascular cavity (gut)4. Tentacles
B. Digestive System/Waste1.Cnidocytes (special defensive cell) have
Nematocysts (coiled organelle with stinging filament)
2. Tentacles push prey through mouth & into gastrointestinal cavity 3. Digestion is
Extracellular, wastes
expelled through mouth.
http://www.emc.maricopa.edu/faculty/farabee/biobk/cnidaria_1.gif
C. Nervous System
1. 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
D. Classes1. Hydrozoa ( 3,700 species) ex- Obelia, Portuguese
Man-O War.2. Cubozoa ex- box jellies, sea wasp3. Scyphozoa “cup-animals” jellyfish4. Anthozoa (6,100 species) “flower animals” like sea
anemones, coralsQUESTIONS:• 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.)
E. Reproductive Systems-
• Some reproduce asexually (see Hydra-budding) especially in warmer temperatures.
• Sexual reproduction- – lower temps– hermaphrodites. – Motile sperm, egg in ovary.
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
http://www.ucmp.berkeley.edu/cnidaria/ctenophora.html
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.