Demonstration Sheets for Turbellaria, Monogenea & Larval Trematodes (Lab 1)
Phylum Platyhelminthes; Class Turbellaria
Dugesia
Be able to recognize the following: 1. Pharynx, 2. Digestive tract (three branches), 3.
Mouth; 4. Eyespots
ZD 1-1; Magnification 4X
Phylum Platyhelminthes; Class Turbellaria
Dugesia
Cross-sections of anterior, middle and posterior regions. Note the cilia on the
epidermis and be able to identify the digestive cavity. This species is free-living and is
not a parasite. It is exhibited to show the characteristics of the class.
ZD 1-22; Magnification 10X
Phylum Platyhelminthes; Class Turbellaria
Bdelloura
Found on gills of horseshoe crabs. Be able to recognize the following: 1. Caudal
adhesive disc, 2. Mouth, 3. Pharynx, 4. Eyespots
Wards 92W 0810; Dissecting
Phylum Platyhelminthes; Class Monogenea
Ergocotyle
Notice the bear trap-like hooks on the opisthaptor. These worms parasitize gills
and can kill sharks in public aquaria. Host was a bonnet-head shark in the Tennessee
Aquarium that had been born in cavity.
Magnification 10X
Phylum Platyhelminthes; Class Monogenea
Neobenedenia
Observe the characteristic hooks on the OPISTHAPTOR.
Magnification 4X
Phylum Platyhelminthes; Class Monogenea
Gyrodactylus
Important pests of trout, bluegills and goldfish in fish ponds. VIVIPAROUS (= live birth)
Parasites are adults at birth. Offspring developing in uterus of parent have developing
embryos in their uteruses, an adaptation resulting in exponential population growth.
See pages 303-304 of your text & Fig 19.14.
PS 1202; Magnification 40X
Phylum Platyhelminthes; Class Monogenea;
Neopolystoma
Parasitic in urinary bladder of turtles. This specimen was taken from a red-bellied slider
collected in the Mobile Delta. The opisthaptor does not have hooks nor anchors.
Specimen; dissecting scope
Phylum Platyhelminthes, Class Trematoda, Subclass Digenea
Eggs of Schistosoma mansoni
This is a very important human parasite in Asia. The eggs are found in feces of
infected humans. If the person defecates in freshwater, a free swimming “miracidia”
larva will emerge from the egg. Eggs of the trematode genus Schistosoma can be
recognized by the presence of a pointed spine.
92W 5167; Magnification 40X
Phylum Platyhelminthes, Class Trematoda, Subclass Digenea
Miracidia
Trematode larval stage that infects the 1st intermediate host, always a mollusk.
Note that the organism has a relatively large eyespot and the external surface appears
“fuzzy” due to the presence of cilia.
Turtox P5.126; Magnification = 40X
Phylum Platyhelminthes, Class Trematoda, Subclass Digenea
SPOROCYST
Found in the 1st intermediate host (usually gastropod snails). Sporocysts are
basically sacs whose internal lining asexually produces embryo-like clones. Unlike
another trematode stage found in 1st intermediate host e.g. rediae, sporocysts do NOT
have mouths. Snail hosts are castrated.
PS 1420; Magnification = 4X
Phylum Platyhelminthes, Class Trematoda, Subclass Digenea
REDIAE
Found in the 1st intermediate hosts (usually gastropods). These stages
reproduce asexually (daughter rediae are visible inside these specimens). They castrate
their snail hosts.
PS 1430; Magnification = 40X
Phylum Platyhelminthes, Class Trematoda, Subclass Digenea
CERCARIAE of Schistosoma
This swimming stage hatches from a redia in the 1st intermediate host and
burrows into the skin of people working in rice paddies. This infective stage is not
reproductive. Each larva has to potential to become only one adult
Magnification = 10x
Phylum Platyhelminthes, Class Trematoda, Subclass Digenea
Cercaria
This family of digenetic trematodes produces very large (relatively speaking)
cercariae & can be found in Alabama freshwater streams. Predatory fish are attracted to
the big, slow-swimming cercariae and “feed” (Deep thought: Who feeds upon whom?)
upon them. Adult worms are in the digestive tracts of predatory fish.
92W 5010; Dissecting scope
Phylum Platyhelminthes; Class Trematoda; Subclass Digenea
Metacercariae
The metacercariae of this species of trematode, Microphallus turgidus are common in
grass shrimp in local salt marshes. The larvae are visible as circular balls within the
muscle tissue in the tail. Sometimes there may be over 50 metacercariae in one shrimp
as seen in the adjacent photo. The bright red metacercariae in the photo are examples
of hyperparasitism as they are infected with a haplosporidian protozoan.
Specimen; dissecting microscope