I. Rotifera and NematodaNematode Body Shape and LocomotionNematode Digestive SystemNematode ReproductionIV. Phylum MolluscaBIO SCI 100 1st Edition Lecture 9 Outline of Last Lecture I. Coral ReefsII. Phylum PlatyhelminthesIII. Phylum Platyhelminthes: DiversityOutline of Current Lecture I. Typical Cestode Lifecycle: Beef tapewormII. Rotifera and NematodeIII. Phylum RotiferaIV. Phylum NematodeV. Phylum MolluscaCurrent LectureI. Typical Cestode Lifecycle: Beef tapeworm1. Cysts consumed in rare beef develop into adult worms in humans are main host.2. Hooks on wall of human intestines and reproduces sexually.3. Proglotids release egg & sperm; enter environment via human feces.4. Cattle (intermediate host) consume contaminated water.5. Cysts enter beef muscle and are eaten by humans.These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Several types of tapeworms infect humans.- Pork tapeworm particularly serious because it encysts in the human brain.I. Rotifera and Nematoda- Both phyla are psuedocoelomates.- The pseudocoelom is:o Fluid filled cavity.o Creates a hydrostatic skeleton.o Supports muscle contraction.o Not lined with a peritoneum.II. Phylum Rotifera:- Microscopic animals.- Found in fresh water & moist soil.- Bilateral symmetry.- Triploblastic: three tissue layers.- Specialized organ systems:- Nervous system- Complete digestive tract- Body covered with a secreted cuticle that is non-living- Free living onlyRotifer Reproduction- Parthenogenesis reproduction: o Females produce diploid (2N) egg.o The diploid egg cannot be fertilized. o They develop into females.o Sexual reproduction:o Females produce haploid (1N) egg.o If haploid egg is unfertilized it develops into male that produces sperm.o Fertilized eggs develop into females.III. Phylum Nematoda- Commonly called “roundworms”.- Most numerous metazoan animals on earth.- Specialized organ systems—nervous & complete digestive tract.- Triploblastic: three tissue layers.- Bilateral symmetry and cylindrical.- Body covered with a secreted cuticle that is non-living.- Free-living or parasitic; every habitat and climate.Nematode Body Shape and LocomotionOuter wall covered in a cuticleFluid filled psuedocoel: Hydrostatic skeletonLocomotion by ‘whip-like’ motion using longitudinal musclesPharynxNervous system- Nerve ganglion: ring of nervous tissue around the pharynx.- Two nerve cords: o One dorsal and one ventral run the length of the body.Nematode Digestive System- Food passes through the mouth (anterior end) and into a muscular pharynx.- Muscular contraction of pharynx moves food through intestines.- Waste eventually passes out of the animal via the anus (complete digestive system).Nematode Reproduction- Mostly dioecious: sexual reproduction—separate sexes.- Males have curled tails to grasp females and use these tails called spicules to insert sperm into females during copulation.- Nematode organs are primarily for feeding and reproducing.Hookworms - Common in the southern US, sub-tropics & tropics.- Larvae live in soil; contact & penetrate bare skin (bare feet).- Eventually migrate to intestines, mature, reproduce and feed.- Eggs released in hosts feces.- Causes anemia.Pinworms - Most common nematode infection of humans in US.- Common in temperate zones (WI) worldwide.- Primarily infecting children.- Infects large intestine.- Eggs cause itching & scratching around anus.- Infection spreads when eggs are ingested, usually due to inadequate hand-washing.- May cause weight loss, but often no symptoms.Roundworms - Common worldwide.- Eggs in the soil in warm, moist climates.- Eggs are swallowed.- Develop into larvae.- Reproduce in the intestines.- Eggs spread from feces to soil.- Infection spread through inadequate hand-washing.Heartworms - Larvae transmitted to dog through infected mosquito bites.- Grow to adulthood and migrate to the heart.- Cause scar tissue to form, and eventually stop blood flow.IV. Phylum Mollusca- 4 Classes:o Polyplacophora: Chitons.o Gastropoda: Snails & nudibranchs.o Bivalvia: Clams.o Cephalopoda: Octopus, squid & cuttlefish.- Mollusc means “soft body”- 90, 000 living species- Triploblastic: having three true tissue layers (endoderm, mesoderm, ectoderm)- Bilateral symmetry - Cephalization evident- Distinct organ-systems: nervous, respiratory & circulatoryBody cavity: Coelomate- First group with a true coelom- The fluid-filled coelom acts as a hydrostatic skeleton- Peritoneum--lines the coelom; covers & anchors organsBody Plan: Two main parts- Head-Foot: Feeding, sensory & locomotion- Visceral mass: Contains two major organ systems: digestive, circulatory, respiratory, and reproductive.- 3 Anatomical Features Unique to Mollusc’s:o The muscular Foot, for locomotion or attachment.o The Radula, for feeding by scraping.o The Mantle; may secrete a shell that grows throughout the animal's life.Respiratory system: gills in mantle cavity. - Water flows through mantle cavity and across gills.Circulatory system: - Heart with two or three chambers.- Few blood vessels.Digestive system: ‘Kidney’ opens into mantle cavity to get rid of wastes.- Reproductive system: usually dioecious.o Lay eggs, which hatch into larvae.o Free-swimming larval stage; band of cilia.o