Flatworms, Roundworms, & Segmented Worms. Phylum Platyhelminthes Flatworms Flat and thin bodies...
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Transcript of Flatworms, Roundworms, & Segmented Worms. Phylum Platyhelminthes Flatworms Flat and thin bodies...
Flatworms, Roundworms, & Segmented Worms
Phylum Platyhelminthes
• Flatworms• Flat and thin bodies• Bilateral symmetry • Most are parasitic
Phylum Platyhelminthes
• Flatworms include planarians, flukes, and tapeworms
• 20,000 species of flatworms
Miscellaneous Information- Flatworms
• Movement- use of moving bodies of water or damp soil, or larger animals transporting them
• Nutrition- parasitic; the flatworm will take in food through same opening it eliminates waste
• Circulatory system- Gastrovascular cavity with one opening
• Digestion and excretion occur through same opening• Reproduction- flatworm splits in two forming a new
flatworm
Tapeworms Information• Can get tapeworm
infection by ingestion of food or water contaminated with tapeworm eggs or larvae
• Can cause intestinal infections
• Symptoms- poor appetite, diarrhea, weakness, gastrointestinal discomfort
Phylum Nematoda
• Roundworms• Ex. Pinworms and
hookworms• 90,000 species of
nematodes• Bilateral Symmetry • Live in wet soil or water• Eat dead leaves and other
materials• Some eat insects that
destroy plant roots• Some destroy plant roots
Flatworm Head
• Head holds attachment hooks for host attachment
• 2 eyespots to help detect light
• Also contains brain called 2 simple brains called ganglia- simple bundles of nerves
Phylum Nematoda
• Some roundworms can live in humans and make them sick
• Roundworms have a complete digestive tract with 2 openings
Nervous System of Roundworms
• Two nerve cords that transmit impulses in the roundworm
Miscellaneous Information- Roundworms
• Reproduction- sexually, eggs deposited in soil after fertilization
• Bilateral symmetry• No formal respiration, circulation, skeletal
systems
Phylum Nematoda
Phylum Annelida
• Annelids are segmented worms• Bodies are divided into many sections or
segments• Live in moist soil, freshwater, or saltwater • 15,000+ species of annelids• Examples: earthworms and leeches
Phylum Annelida
• Earthworms– Have bristlelike Setae on each segment- helps in
movement– Tunnel through soil to eat small pieces of food– Tunnels will loosen the soil and allow air to enter
which helps plants to grow
Leeches and Us
• Used in medicinal treatment• Abscesses, painful joints, glaucoma,
myasthenia, and to heal venous diseases and thrombosis
Phylum Annelida
Miscellaneous Information- Segmented Worms
• Nervous system- ganglia nerve centers in each segment that are connected by nerve cords to brain
• Closed circulatory system- like humans • Gas exchange through skin- need for worm to live near
water • Digestion- complete internal digestive tract that runs
length of body– Gizzard- muscular sac and hard particles help grind soil and
food before they pass into intestine Nephridia- collect/remove waste from each segmentPg. 731 is a good reference for earthworm body
Miscellaneous Information- Segmented Worms
• Reproduction- Hermaphrodites• Produce both eggs and sperm
Phylum Annelida
• Leeches– Eat small invertebrates– Can attach to skin of vertebrates and feed on its
blood– Anesthetics in chemicals of bite to prevent pain– Leech secretes chemical so blood does not clot
Bilateral Symmetry and Body Plans
• All bilaterally symmetrical animals developed from 3 embryonic cell layers:– Ectoderm– Endoderm– Mesoderm
– 3 types- Acoelomates, Pseudocoelomates, Coelomates
Acoelomates
• Develop from the 3 layers but have no body cavities
• Digestive tract extends throughout body• May have been first group of animals to
evolve• Ex. Flatworms
Acoelomates
Pseudocoelomates
• Develop from the 3 layers• BUT also has a space that develops between
the endoderm and mesoderm- called a pseudocoelom (difference between flatworm and roundworm)
Pseudocoelomates
Coelomates
• Body cavities form from Coelom (fluid filled space that is completely surrounded by mesoderm where specialized organs and organ systems, serves to cushion and protect organs)
• Humans, insects, fishes• Example: Earthworm • Greatest diversity among animals
Coelomates
Earthworm
Compare and Contrast
• Flatworm and Earthworm digestive tracts • One opening to flatworm’s digestive tract (pharynx)• Earthworm’s digestive tract has 2 openings (mouth
and anus)
3 types of worms Segmented Worms Roundworms Flatworms
Phylum Annelida Phylum Nematoda Phylum Platyhelminthes
Segmented/sectioned bodies, bilateral symmetry
Bilateral symmetry Bilateral symmetry, flat and thin bodies
Moist soil, freshwater, or saltwater
Wet soil or water Parasitic- live inside a host or in water
Complete digestive tract- 2 openings (mouth and anus)
Complete digestive tract with 2 openings (mouth and anus)
One digestive opening (pharynx)
Coelomate- form from coelom (fluid filled space surrounded by mesoderm)
Pseudocoelomate- develop from 3 layers, with space between endoderm and mesoderm called Pseudocoelom
Acoelomate- develop from 3 layers but have no body cavities
Earthworms, leeches Pinworms, hookworms planarians, flukes and tapeworms