Exercise 7 - Nematoda

• Phylum Nematoda - Morphologically, they are characterized as being round, bilaterally symmetrical and unsegmented. They are pseudocoelomate, with cuticle and a complete digestive tract. Circulatory and respiratory systems are absent.
• Nematodes are sexually dimorphic, with the female usually larger than the male.
• What are the two classes under Phylum Nematoda?

  1 Class Aphasmidia (Adenophorea)

  2 Class Phasmidia (Secernentea)
• Class Aphasmidia - Phasmids lacking, amphids usually well developed, excretory system of renette cells (glandular); cauda and hypodermal glands common, mostly free-living, but includes some parasites. Trichuris, Trichinella.
• Class Phasmidia - Phasmids present near posterior tip, amphids poorly developed, excretory system of canals with or without associated glandular cells. Both free- living and parasitic. Ascaris, Ancylostoma, Enterobius.
• Trichuris (whipworm). The shape and general appearance of this worm resembles a whip, hence the name whipworm.
• They are common inhabitants of the caecum and large intestine of many animals, including dogs, rodents, pigs, monkeys, and man.
• The anterior part of the body is hair-like, the lash comprises roughly three-fifth of the body, while the robust posterior comprises the remaining part
• A spear-like projection at the anterior extremity enables the parasite to penetrate and attach itself to the intestinal mucosa of the host.
• The slender anterior portion contains a long esophagus, which resembles a string of beads.
• Each bead represents a cell (stichocyte).
• It terminates into the anal opening, located at the extreme posterior end of the body.
• Males nematodes have a single long spicule, retractile into a sheath, with a spiny, bulbous end.
• In contrast, the female has a blunt posterior
• Trichinella. The trichina worm, though an intestinal parasite as an adult, is quite different from other intestinal worms. The serious and often fatal results of this worm are due to the adult worm in the intestine.
• T. spiralis are encysted larvae lying parallel to the muscle fibers of the host.
• The cyst is made up of an inner fibrous layer surrounding the worm and an outer hyaline layer.
• Enterobius. The worm is popularly called pinworm, seatworm or threadworm (E. vermicularis).
• The mouth, provided with three distinct retractile lips, leads into the esophagus with a distinct esophageal bulb.
• Ancylostoma. The adult hookworm lives in the intestine of dogs, cats and man.
• This worm has large wide buccal capsule with 3 pairs of ventral teeth.
• The large flaring male bursa, supported by long slender rays, has short, stout copulatory spicules, arranged in a manner characteristic of the species.
• Turbatrix aceti (common vinegar eel). This free-living nematode thrives in the associated bacteria of non-pasteurized vinegar (“sukang puti”).
• Ascaris. We will examine one of the largest known species of nematode, the intestinal roundworm Ascaris, which occurs in the intestines of humans and pigs.
• Males can be easily distinguished by their curved tails with a pair of copulatory spicules, which protrude from the cloaca (serving as sperm guide), while females have blunt tail.
• What type of nematode, its class, as well as its sex does the picture below shows?

  Ancylostoma (Hookworm) which belong to Class Phasmidia

  Sex: Female

  
• What type of nematode is this?

  Trichuris trichiura (whipworm) belong to Class Aphasmidia

  
• What type of nematode is this and what's its gender?

  Ascaris (male) belong to Class Phasmidia

  
• What type of nematode is this and what's its gender?

  Ascaris (Female)

  
• What type of nematode is this?

  Turbatrix aceti which belong to Class Phasmidia

  
• What type of nematode is this?

  Trichinella spiralis belongs to Class Aphasmidia

  
• What type of Nematode, its sex, and class where it belong shows in the picture below?

  Genus: Ancylostoma (Hookworm)

  Class: Class Phasmidia

  Sex: Male