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Basal animals are also known as:
Parazoans. Non-coelomate invertebrates
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What are two things that basal animals do not have?
- Do not have tissues and organs
- Do not have a definite symmetry
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Phylum Porifera aka...
Sponges
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What is the major group of basal animals (parazoans)?
Phylum Porifera (Sponges)
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How many species are in phylum Placozoa?
- Only one
- Trichoplax adhaerens
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Trichoplax adhaerens looks like a...
- "hairy pita bread"
- A bilayer of a few thousand cells
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How does Trichoplax Adhaerens reproduce?
By dividing into two individuals or by budding off many multicellular individuals.
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6 traits of Phylum Porifera:
- 1. Marine AND freshwater
- 2. Size ranges from a few mm to 2 meters in diameter
- 3. Most asymmetrical... a few with radial symmetry
- 4. Larval sponges are free swimming
- 5. Adult sponges remain attached to substrate for the remainder of life
- 6. Sponges defend themselves by producing chemicals that repel predators
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Sponges reproduce (sexually/asexually)
Both! Sexually and asexually
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What is unique about larval sponges?
They are free swimming
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How do sponges defend themselves?
Producing chemicals that repel predators
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Phylum porifera (sponges) exist in what type of water environment?
Both marine and freshwater.
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What is unique about the cells of a sponge?
- If all the cells are separated, the cell types will seek each other out and reassemble the entire sponge.
- No other animal can do this!
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In sponges, there are 8 types of cells with specialized functions (CAPPMOSS)...
- 1. Choanocytes
- 2. Amoebocytes
- 3. Pinacodem
- 4. Porocytes
- 5. Mesohyl
- 6. Osculum
- 7. Spicules
- 8. Spongin
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Specialized sponge cell type 1: choanocytes
- collar cells
- water circulation through sponge
- capturing, engulfing, digesting food particles
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Specialized sponge cell type 2: Amoebocytes
- Distribute nutrients through sponge
- TOTIPOTENT CELLS
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Specialized sponge cell type 3: Pinacoderm
- made of flattened cells
- make up other epithelium
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Specialized sponge cell type 4: Porocytes
flattened cells that line the pores of the ostia
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Specialized sponge cell type 5: Mesohyl
- Gelatinous, protein-rich matrix
- located between inner and outer cell layers
- NOT THE SAME AS MESODERM!
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Specialized sponge cell type 6: Osculum
- Large openings where water exits the sponge
- Osc= mouth
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Specialized sponge cell type 7: Spicules
needlelike structures made of calcium carbonate or silica
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Specialized sponge cell type 8: Spongin
tough protein fibers that make up the skeleton of some sponges
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Differentiate between ostia and oscula:
- Ostia: where water enters the sponge
- Oscula: where water exits the sponge
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In sponges, asexual reproduction occurs by...
fragmentation
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In sponges, sexual reproduction involves...
fusion of sperm and egg
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Sponges are hermaphroditic, meaning...
they have both male and female parts
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Parazoan vs Eumetazoa:
- Parazoan: Animals without true tissue
- Eumetazoa: Animals WITH true tissue
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True or false: All cnidarians are carnivores...
True!
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Most of the 10,000 species of cnidarians are (marine/freshwater) but very few live in (marine/freshwater).
- Most are marine
- Few are freshwater
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Are cnidarians diplo or triploblastic? Why?
- Diploblastic.
- They have no mesoderm
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Cnidarians have (organs/tissue) but no (organs/tissue).
- They have tissues
- They do not have organs
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Which of the following systems does the cnidarian have?
E. nervous
they have a nervous net
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Nematocycts are unique to this phylum.
Cnidaria
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What are the two body plans of cnidarians?
- Polyp -- typically sessile
- Medusa -- swims freely in water
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In both basic body plans of cnidarians, the mouth opens into a _____ and is surrounded by tentacles.
GVC (Gastrovascular cavity)
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True or false: The GVC in cnidarians is a stomach.
- FALSE!
- Cnidarians do not have ANY organs
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They two-layered body wall of cnidarians is made up of: ______ and _____.
epidermis and gastrodermis
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What holds the epidermis and gastrodermis together in cnidarians?
An acellular mesoglea-middle glue
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The GVC in cnidarians serves as a ______ skeleton.
Hydrostatic
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In cnidarians, polyps will sometimes build an exoskeleton of ____ or _____ _____ for extra support.
chitin or calcium carbonate
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True or false: Sea anemones have no skeleton; neither do Medusae.
True!
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Medusa forms are (solitary/colonial) while polyps can be (solitary/colonial).
- Medusa -- Solitary
- Polyps -- Colonial
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In the life cycle of cnidarians, some have...
- 1. Polyps only
- 2. Medusa only
- 3. Both polyps and medusa (sexes are separate)
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Gonorchism
- Refers to the life cycle of cnidarians having both polyp and medusa.
- Both sexes are seperate
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The life cycle of cnidarians:
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In some, but bot all species of cnidarian, the polyp can produce other polyps asexually by...?
- Dividing
- Budding
- Or breaking off bits that regenerate
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What is a major evolutionary innovation of cnidarians?
digestion
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Why can cnidarians take in larger prey items than a sponge?
- Extracellular digestion of food inside the GVC.
- Once partial digestion occurs in the GVC, other cells take up fppd fragments by phagocytosis.
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Namatocysts:
microscopic stinging capsules
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What are some details about nematocysts?
- capsule everts upon proper stimulation
- Releases barbs (some have venom) that immobilize or kill prey
- Only discharged once
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Cnidarians are grouped into four (or five) classes:
- 1. Class Anthozoa-flowering animals
- 2. Class Cubozoa-box jellies
- 3. Class Hydrozoa-the hydroids
- 4. Class Scyphozoa-cup animals
- 5. Class Staurozoa-star jellies
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Cnidarian class #1: Anthozoa
- "Flowering animals"
- include sea anemones and corals that exist as solitary or colonial polyps
- Form Coral Reefs
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Cnidarian class #2: Cubozoa
- Box Jellies
- medusa stage dominant (polyp reduced or unknown)
- poison stronger than cobra venom
- image-forming eyes
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Cnidarian class #3: Class Hydrozoa
- The hydroids
- both polyp and medusa stages in life
- only class with freshwater members
- some marine hydroids and medusae are bioluminescent
- Portuguese man-of-war
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Cnidarian class #4: Scyphozoa
- Jellyfish or "cup animals"
- medusa more prominent and conspicuous
- propel through ocean by jetting water from GVC
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Cnidarian class #5: Staurozoa
- Star Jellies
- Once included in class scyphozoa
- resembles a medusa but is attached to substrate by a stalk like structure
- Planula larva creeps rather than swims or drifts
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Phylum Ctenophora aka...
Comb jellies (cteno = comb)
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Do ctenophora live in freshwater or ocean water?
In the ocean, never freshwater
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4 unique characteristics of Phylum Ctenophora:
- 8 rows of combelike plates of fused cilia along two long retractable tentacles
- colloblasts: cells that release strong adhesive
- largest animal to use cilia for locomotion
- many are bioluminescent
- may be triploblastic and have bilateral symmetry
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This is the largest animal to use cilia for locomotion...
Ctenophora (comb jellies)
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Bilatarian Acoelomates key feature:
- Bilateral symmetry
- functional specializations: anteriorly located nerve receptors
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Phylum Platyhelminthes aka...
- Flatworms
- (platy=flat + helminthe= worm)
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General traits of phylum platyhelminthes:
- flattened and solid body (aside from incomplete digestive cavity)
- free-living flatworms live in marine, freshwater, and moist terrestrial habitats
- scavengers or carnivores
- move with cilliated epithelial cells and well developed muscles
- parasitic flatworms live inside bodies of other animals; rage from 1 mm to many meters.
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Digestion in flatworms:
- incomplete gut that is branched
- functions in both digestion AND distribution of food
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Excretion and Osmoregulation in platyhelminthes:
- primary function of excretory system is water balance
- waste diffuses into gut and expelled through the mouth
- flame cells with "flickering" flagella move water and excretory substances
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What are flame cells and where are they found?
- cells with "flickering" flagella that move water and excretory substances
- Found in excretory system of platyhelminthes
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Nervous system and sensory organs of platyhelminthes:
- anterior cerebral ganglion
- nerve cords and cross connections that have ladder-like appearance
- eye spots distinguish light from dark
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Platyhelminthe reproduction:
- most are hemaphroditic
- cross-fertilization is internal
- can regenerate missing parts
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What are the 3 classes of Platyhelminthes?
- 1. class Turbellaria (turbulant air=flame cells)
- 2. Class Trematode: flukes
- 3. Class Cestoda: tapeworms
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Platyhelminthe class 1: Turbellaria
- "turbulent air=flame cells"
- free-living flatworms such as Planarians
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Platyhelminthe class 2: Trematoda
- Flukes
- life cycle most often involves two or more hosts
- many flukes cause disease in humans (schistomiasis - blood fluke)
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Explain the life cycle of Class Trematoda (flukes):
- involves two or more hosts
- intermediate host usually snail
- final host some type of vertebrate
- Schistosomiasis--snail--humans
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Platyhelminthes class 3: Cestoda
- tapeworms
- no digestive cavity -- absorbs nutrients through outer surface from host's intestine
- body portions: scolex, neck, proglottids
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Name the body portions of Platyhelminthes class Cestoda:
- Scolex for attachment
- neck
- proglottids=repetitive sections that are largely reproductive
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Pseudocoelomates have a body cavity that lies between tissues derived from ____ and tissues derived from ____.
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Pseudocoelom serves as _____ ______.
Hydrostatic skeleton
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Phylum nematoda aka...
Roundworms
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General characteristics of Nematoda:
- ecdysozoans that molt cuticles
- 20,000 recognized species
- marine and freshwater form
- many are parasites of animals and plants
- highly abundant in soil (millions)
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Explain the nematode structure:
- Bilateral, unsegmented worm
- flexible cuticle is molted as they grow
- oxygen and carbon dioxide exchange occurs through cuticle
- have longitudinal muscles, but NO circular muscles so can lengthen or shorten but can't change diameter.
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This type of worm has longitudinal muscles but no circular muscles.
Roundworms (Nematoda)
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Traits of Nematode reproduction:
- sexual reproduction
- gonochoric (seperate sexes)
- sexual dimorphism
- internal fertilization
- indirect development
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Gonochoric means...?
Separate sexes (nematodes)
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Sexual dimorphism means...?
Male and female look different
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Nematode lifestyles include the following...
- hunters
- parasites of plants or animals
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Nematode-caused human disease: Necator
- found in southern states causes anemia
- hookworms
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Nematode-caused human disease:Trichinella
- causes trichinosis
- mature worms form high resistant calcified cysts in muscle tissue
- Don't eat raw pork or bear meat
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This disease is caused by eating raw or undercooked pork or bear meat.
Trichinosis
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Nematode-caused human disease: Enterblus vermicularis
- Pinworms
- infect 30% of children and 16% of adults in the US.
- Live in human rectum and cause itching
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Pinworms are caused by what type of nematode?
Enterobius vermicularis
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Nematode-caused human disease: Ascaris lumbridoides
- Infects 1 in 6 people worldwide
- less common in areas of modern plumbing
- Lives in human intestines
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Nematode-caused human disease: Wuchereria Bancrofti
- filarial worms that cause elephantiasismainly seen in tropical areas
- transmitted by an intermediate bloodsucking host such as mosquito
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This nematode causes elephantiasis.
Wuchereria bancrofti
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