Radiata Metazoa Ancestral colonial flagellate Deuterostomia Eumetazoa Protostomia

“Radiata” Metazoa Ancestral colonial flagellate Deuterostomia Eumetazoa Protostomia Bilateria Phylum: Nematoda pseudocoelomate Nematoda Nemertea Rotifera Arthropoda Annelida Mollusca Platyhelminthes Chordata Echinodermata Brachiopoda Ectoprocta Phoronida Ctenophora Cnidaria Porifera

Kingdom: Animalia Phylum: Nematoda (formerly Aschelminthes) • non-segmented, smooth worms • tapered at both ends • bilateral symmetry • >80, 000 species described • most common soil inhabitant • 15, 000 parasitic species • generally less than 5 cm (some parasitic ones longer) • covered in thick, tough, protective cuticle • cuticle is a syncitial epidermis • molt several times during lifespan • triploblastic • pseudocoelomate- 1 st group to evolve a body cavity

Kingdom: Animalia Phylum: Nematoda (formerly Aschelminthes) pseudocoelomate- coelom partially lined with mesoderm

Advantages of Evolution of a Body Cavity • fluids moving within cavity can function as circulatory system • fluid in cavity makes body rigid allowing for muscle driven body movement, a “hydrostatic skeleton” • organs can function without being deformed by body movement • food movement not controlled by locomotion of animal making digestion and waste removal more efficient

Kingdom: Animalia Phylum: Nematoda (formerly Aschelminthes) • complete digestive system • one-way digestion (mouth and anus) • tube within a tube • nervous system • sensory structures and ganglia at head • nerve ring with ganglia around the pharynx • ventral and dorsal nerve cords • reproduction is sexual • most have separate males and females (dioecious) • reproductive organs in body cavity • females release chemical attractants

Kingdom: Animalia Phylum: Nematoda (formerly Aschelminthes) • locomotion • longitudinal muscles under epidermis • no circular muscles • can only undulate side-to-side (whip-like motion) • no cilia • “hydrostatic skeleton” aids in movement • excretory system • waste moved via fluid in body cavity • may have excretory ducts/pores as well as gland cells for waste removal • no respiratory or circulatory system • gas exchange by diffusion • food and nutrients distributed via fluid in body cavity

Kingdom: Animalia Phylum: Nematoda (formerly Aschelminthes) cross-section

Phylum: Nematoda, Genus: Ascaris lumbricoides • parasite of humans that causes ascariasis • largest intestinal roundworm (15 -35 cm) • can block intestine, bile duct, pancreatic duct • in tropical, sub-tropical areas with poor sanitation • caused by accidental ingestion of fertilized eggs • most common human helminth infection worldwide • infection easily treated with anti-helminthic drugs.

Phylum: Nematoda Hookworms hookworms attached to intestinal mucosa • adults attach themselves to intestinal mucosa • feed off of blood • can cause severe anemia • humans contract when larval form bores through skin after contact with contaminated soil • treatment: freezing if still on skin, anti-helminthic drugs

Phylum: Nematoda Pinworms • geographically found everywhere, common here • common in school age children, spread by oral-fecal route • adult male 1 -3 mm, female 8 -13 mm • live in large intestine • eggs ingested hatch in small intestine, then migrate to large intestine to mature • eggs can survive 2 -3 weeks outside human body • treatment: anti-helminthic drugs kill larvae and adult, not eggs Beware the 10 second rule!

Phylum: Nematoda Trichinella spiralis causes trichinosis • larvae encysted in striated muscle • cysts formed by host immune response • larvae passed to another organism when undercooked meat is eaten • in new host, cyst digested in stomach releasing worm, then adult develops in intestine • adult worms deposit larvae in lymph vessels and wall of intestine • larvae migrate throughout body • larvae that make it to muscle encyst in their new host

Phylum: Nematoda Trichinella spiralis causes trichinosis • humans can get from eating undercooked pork • most damage of infection is when 1/2 billion larvae bore through the body at once • severe cramping, fever, anemia, weakness • some victims may have permanent muscular damage; others may die • prevention: thoroughly cook pork, freeze pork • rare in developed countries

Phylum: Nematoda Trichinella spiralis causes trichinosis

Phylum: Nematoda Filaria worms • significant in human disease • intermediate host (vector) is arthropod • definitive host is a vertebrate • cause of. . . • elephantiasis in humans • heartworm in dogs

Phylum: Nematoda Filaria worms: Wuchereria bancrofti causes the disease elephantiasis • found in tropical and subtropical areas • spread by bite of certain mosquitoes • adult worms live in lymphatic system • accumulate to large numbers and block lymph flow • causes fluid accumulation, swelling, especially in the lower extremities

filaria worms cause the disease elephantiasis

Just FYI:

Phylum: Nematoda Filaria worm causes heartworm in dogs • intermediate host = mosquito • definitive host = dog • fatal to dog

“Radiata” Metazoa Ancestral colonial flagellate Deuterostomia Eumetazoa Protostomia Bilateria Phylum: Rotifera pseudocoelomate Nematoda Nemertea Rotifera Arthropoda Annelida Mollusca Platyhelminthes Chordata Echinodermata Brachiopoda Ectoprocta Phoronida Ctenophora Cnidaria Porifera

Kingdom: Animalia Phylum: Rotifera • microscopic (50µm - 2 mm long) • usually free-living, in moist soil or aquatic environments • corona • double crown of cilia at anterior end • look like rotating wheels when they beat • draw water current into mouth for feeding & locomotion • foot • at posterior end • when feeding, attaches to surface • nearby cement gland generates the adhesive • mastax • complicated muscular pharynx • seven hard jaw-like structures crush food

Kingdom: Animalia Phylum: Rotifera • pseudocoelemate • complete digestive system • have excretory and reproductive systems • no circulatory or respiratory system • reproduction can be sexual or by parthenogenesis • parthenogenesis- in some species females produce 2 different kinds of diploid eggs, female and male, that develop without fertilization to diploid adults • in some species, eggs can develop as dwarf males that cannot even feed themselves, only survive long enough to produce sperm to fertilize females (sexual dimorphismsexes take on 2 different forms)

Kingdom: Animalia Phylum: Rotifera cilia beat in opposite directions to create current (cement glands)

The Table for Nematoda: Symmetry: bilateral Segmentation: none Mesoderm present: yes, triploblastic, has only longitudinal muscles Type of body cavity: pseudocoelomate; fluid filled pseudocoel enclosed by cuticle forms hydrostatic skeleton Ciliated larva: have larva that molt (shed cuticle as they grow) Protostome: no? (this is under debate among scientists, newer molecular evidence may revise this) Cleavage/cells: determinate Nervous system: present; 2 nerve cords (dorsal & ventral)

The Table for Nematoda: Digestive system: complete one-way system (mouth & anus); pharynx usually muscular; some heterotrophs but mostly parasites Excretory system: yes, excretory ducts and pores to eliminate waste, some have gland cells and/or canal systems, too Reproductive system: sexes usually separate (dioecious); male reproductive tract opens to rectum forming common exit called the cloaca; female reproductive tract opening separate from digestive tract Circulatory system: none Members: hookworms, pinworms, common roundworm, trichinella Habitat: moist soil; the most numerous inhabitant of the soil; also found in aquatic environment; some parasites Relationship to other phyla: N/A

The Table for Rotifera: (If nothing is listed for a category, assume it is the same as for Nematoda. ) Reproductive system: sexual or by some by parthenogenesis (produce diploid eggs that grow to diploid adult without fertilization); some exhibit sexual dimorphism producing degenerate dwarf males that live only long enough to fertilize eggs Members: rotifers Habitat: freshwater and marine environments, moist soil Relationship to other phyla: cuticle suggests rotifers are close relatives of roundworms