The Ecdysozoa The Ecdysozoa include the following phyla: Arthropoda, Onychophora, Tardigrada, Kinorhyncha, Priapulida, Loricifera, Nematoda and Nematomorpha.

The Ecdysozoa Characteristic shared by ecdysozoans Three-layered cuticle composed of organic material, which is periodically molted as the animal grows. The process of molting is called ecdysis and gives the group its name. The Ecdysozoans lack locomotory cilia, produce mostly amoeboid sperm. Their embryos do not undergo spiral cleavage as in most other protostomes.

Phylum Nematoda the roundworms

Phylum Nematoda Nematodes are among the most abundant animals on earth - over 25,000 species have been described. Majority of nematodes are free-living in every conceivable habitat. free-living species are commonly microscopic in size. A few species cause disease of great importance to humans and domestic and wild plants and animals.

Phylum Nematoda If all the matter in the universe except the nematodes were swept away,…we should find our world’s mountains, hills, vales, rivers, lakes and oceans represented by a thin film of nematodes. N.A. Cobb (1914, Yearbook of the United States Department of Agriculture) 5

Phylum Nematoda Parasitic and free-living Numerous and diverse 6.7 ml of coastal mud 1,074 individuals 236 species Rotting apple: 90 thousand individuals Farmland: 9 billion per acre 8

Phylum Nematoda Roundworms Dioecious (mostly) Tapered at both ends Pseudocoelomate Pseudocoel Complete digestive system Mouth and anus 9

Pseudocoelomate Characteristics “false” body cavity ectoderm pseudocoelom mesoderm Gut endoderm the pseudocoelom is lined by mesoderm on ONE side only 10

Characteristics of the Phylum Nematoda 11

Phylum Nematoda Triradiate pharynx Pharynx between mouth and esophagus 12

Photo by Agustín Jimenez 13

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Phylum Nematoda Body covered by: Cuticle Noncellular Molts 4 times during development 15

Elaboration of Cuticle Aspidodera 16

Phylum Nematoda Movement Contraction of muscles Longitudinal muscles Hydrostatic skeleton Fluid filled pseudocoel Cuticle Contraction of muscles Antagonized by pressure of pseudocoel and hydrostatic skeleton 17

Tube within a tube Female Esophagus Uterus Vulva 18

Tube within a tube Male Cloaca = common area for openings of genital pore and anus 19

Copulatory Spicules Hold vulva open during copulation 20

Reproduction Dioecious Some Monoecious (rare) Parthenogenesis Females reproduce without males Unfertilized eggs develop into new individuals Sometimes systems are mixed (heterogamy) Mate Finding Pheromones Thigmotaxis (papillae near reproductive structures) 21

Mating Behavior Male coils tail around female and searches for vulva. 22

Papillae Sensory structures 23

Characteristics of the Phylum Nematoda Nematode development is similar in all nematodes.  Consists of 4 juvenile stages between the egg and adult. Each stage is separated by a molt of the cuticle.   Hatch M1 M2 M3 M4 Egg J1 J2 J3 J4 Adult Juvenile stages may be passed within the egg, free-living in soil, parasitic in an intermediate host, or parasitic in definitive host. 24

parasite of soybean plants parasite of tomato plants Ecology Many nematodes are important parasites of both plants and animals. parasite of soybean plants parasite of tomato plants

Parasitic Nematodes 26

Order Oxyurida Rhoden and Bolek (2011)

Order Oxyurida Rhoden and Bolek (2011)

Order Oxyurida Enterobius vermicularis Large esophageal bulb Pinworms Enterobiasis Large esophageal bulb Sharp, pointed tail Alae at anterior end Cosmopolitan Common in people Relatively unpathological

Direct life cycle Adults live in ileocecal region of intestine (wander throughout gut) Feed on bacteria and organic material from cells At night, females migrate to anus and lay eggs (up to 16,000 each) Embryonates within 6 hours Infection via ingestion of embryonated eggs Or may hatch on perianal folds and wander up intestine

Symptoms and Pathology 1/3 asymptomatic Pruritus Lesions from feeding not significant Secondary infections can occur Itching can lead to secondary infections

Pinworm Neurosis Nervousness Children Parents Fidgeting, restlessness, irritable, nail biting, nose picking Due to toxemia and damage of epithelium Children Parents Obsessive cleaning

Diagnosis Scotch tape test Flashlight test Mebendazole Treat entire family

Diagnosis of Enterobius vermicularis Use of double-stick tape on a tongue depresser. This is pressed against the perianal folds where eggs will stick to the tape. Tape is then stuck onto a microscope slide and examined for eggs.  

Enterobius vermicularis Almost anybody can become infected with this parasite. No social class is exempt. These parasites soon become "family affairs". Once one person, usually a child becomes infected, other family members will undoubtedly also become infected.  

Epidemiology Very Prolific Eggs build up fast Clothing and bedding Eggs very light and float Easily distributed Eggs viable for up to a week

Prevention and Control Not very serious Good hygiene

Horse Pinworms, Oxyuris equi

Horse Pinworms, Oxyuris equi

Horse Pinworms, Oxyuris equi

Guinea worm (Dracunculus medinensis):

Guinea worm (Dracunculus medinensis): Transmitted by infected copepods in drinking water Juveniles move into the body cavity Female adult migrates to the subcutaneous tissue, causes an ulcer/blister, and releases juveniles through hole when host comes in contact with water

Guinea worm (Dracunculus medinensis): Traditionally removed by winding the worm around a stick over the course of several days This may be the basis for the Caduceus symbol used in the medical field

Juvenile Dracunculus medinensis and Copepod Intermediate host

Life Cycle

Drinking Water Guinea worm sufferers often try to ease the burning pain caused by the blister by stepping into water—the very same source of drinking water for their community.

Guinea worm (Dracunculus medinensis): Female worms cause allergic reactions during blister formation, causing an intense burning pain producing allergic reactions (rashes, nausea, diarrhea, dizziness, and localized edema). When the blister bursts, allergic reactions subside, but skin ulcers form, through which the worm can protrude. Only when the worm is removed is healing complete. Death of adult worms in joints can lead to arthritis and paralysis in the spinal cord.

Carter Center: Guinea Worm Eradication Jimmy Carter 39th President of the United States

Distribution

Controlled Immersion

Current Distribution

Chad, Ethiopia, Mali, and South Sudan