Parasites from Miscellaneous Phyla & Apicomplexa (non-malaria) (Lab 11)

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1 Parasites from Miscellaneous Phyla & Apicomplexa (non-malaria) (Lab 11) Phylum Mollusca; Class Bivalvia; Family Unionidae Glochidium larvae Freshwater unionid mussels are able to colonize upstream habitats by producing larvae that parasitize fish. The larvae burrow into fin and gill tissues where they feed upon host fluids as a true parasite. Upon completion of development, the juveniles drop off hosts, who have moved up and downstream since infection, burrow into the substrate of the stream and become filter feeders. CBS Z 1480, 10X Phylum Annelida; Class Hirudinea Leech Leeches are segmented worms with two suckers. Although many are true predators of invertebrates, their infamous reputation comes from the few species that are micropredators on vertebrates. 92W 1851, Dissecting scope Phylum Annelida; Class Hirudinea Leech The species on display was taken from a bat ray in the Gulf of Mexico., Dissecting scope Phylum Nematomorpha Horsehair Worm These fairly large worms have juvenile stages that parasitize the body cavities of large arthropods. When nematomorphs mature in terrestrial hosts, their hosts seek out and enter freshwater which stimulates the worms emerge resulting in host death. This specimen was found in a well in Brazil. The sudden appearance of adult horsehair worms in water troughs led to the folk wisdom explanation that these worms developed from hairs that had been shed by drinking horses. Nematomorphs can be distinguished externally from nematodes by the presence of blunt (rather than pointed) ends., Dissecting scope

2 Phylum Nemertea Carcinonemertes Most nemerteans are free-living predatory worms that catch their prey with a conspicuous proboscis that you cannot see on these specimens. Members of the family represented by these specimens are symbionts that feed on the eggs of crabs. They live in the external egg masses of egg-bearing females and feed on the eggs and are known as egg predators., Dissecting Scope Kingdom Plantae Haustoria of Dodder This twig is from an oak growing across the street from the Life Science Building. It was parasitized by a dodder plant whose yellow tendrils have since fallen off. Open wounds or scars where the dodder s haustoria penetrated the host tree are visible., Dissecting Scope Kingdom Plantae Dodder Although some species of dodder contain low numbers of chloroplasts giving them a slight yellow green tinge, the plants are true parasites as they acquire nutrients from host plants. This specimen was taken from Dauphin Island.

3 Kingdom Plantae Indian Pipe This specimen was collected from the pine forest along the university s Nature Trail. Indian pipes have no chlorophyll and can be recognized in the wild by their opaque white coloration. The dark coloration of this specimen is an artifact of preservation. Indian pipes actually parasitize ectomychorrhizal fungi that form mutualistic associations with plants. The parasitic plant extracts sugars from the fungus that were produced in the tree. Phylum Myxozoa PANSPOROBLAST The cyst located on gills of this fish is a pansporoblast and is filled with spores that will infect any predatory fish that feeds on this host. CBS PS 445, 10X Demonstration Sheets for Apicomplexa Coccidea that are not malaria (Lab 11) Figures and page numbers from Roberts & Janovy 8 th ed, 2009 Phylum Apicomplexa; Subclass Gregarinasina; Suborder Septatorina Cephaline Gregarines Gregarines in this suborder are common in insects. The two slides on display are cross-sections through larval mealworms. Members of the Septatina or cephaline gregarines are characterized by a septum that divides the cell into two sections. The posterior portion or deutomerite contains the nucleus. Observe the protomerite, septum, epimerite (hard to see), deutomerite, and nucleus in deutomerite. PS 415, 40X

4 Phylum Chordata; Subphylum Vertebrata; Class Osteichthyes CANDIRU These catfish live in the Amazon and Orinoco Rivers of South America. They feed on gills of other fish which they locate by following an ammonia trail. Strictly speaking, their trophic and ecological interactions classify them as micropredators and along with vampire bats, they have adapted a life-style that is close as vertebrates have come to true parasitism. Occasionally candiru, responding to ammonia in a urine stream from a mammal taking a leak in a stream, will become lodged in the urethra of the unfortunate victim. Phylum Cnidaria; Class Anthozoa Parasitic Sea Anemone Edwardsia sp. This specimen (undescribed species) was collected from the medusa stage of another cnidarian, the moon jellyfish Aurelia, in the Gulf of Mexico. The parasite feeds on the gonads of its hosts. Due to the fixation process, the tentacles of the sea anemone have withdrawn into its body cavity., Dissecting Scope Healthy Human Lung Tissue Compare with the adjacent display taken from a patient with a chronic infection of Toxoplasma gondii. CBS H7745, 10X

5 Family Sarcocystidae Toxoplasma gondii Lung tissue from a person, probably with a suppressed immune system, suffering from an infection of T. gondii. In situations such as this, the fast growing type of merozoite (= tachyzoites) destroy cells causing extensive lesions in the lung, liver, brain, heart, and eyes. Compare the density of cells and the surface area available for oxygen absorption in this sample with the healthy lung tissue in the adjacent display. Carolina , 10X Family Sarcocystidae Tachyzoite stage of Toxoplasma gondii Merozoite stage known as tachyzoites (tachy = rapid) in the peritoneal fluid of a mouse. These organisms cause toxoplasmosis in humans. Felines, such as the domestic cat, are definitive hosts. See Figure 8.14 (p. 136). CBS PS 965, oil Family Sarcocystidae Toxoplasma gondii in Brain Cysts containing bradyzoites in brain tissue. In healthy vertebrate (nonfeline) intermediate hosts with non-compromised immune systems, T. gondii will eventually become quiescent and form cysts such as these in the central nervous system. Although alive, the parasites stop reproducing asexually. Sounding like the plot of a science fiction story, infected hosts (including humans) walk around with another organism literally living in their brains. The parasite relies upon consumption of the intermediate host by a feline predator for completion of its life-cycle. Lab studies have shown that infected mice change their behavior and do not avoid areas scented with cat urine as do uninfected mice. More recently, a study in Europe found that a higher percentage of men involved in automobile accidents possessed antibodies to T. gondii than expected suggesting infected men may lose their sense of danger. 92W 4841, 40X