By: Trent Paffenroth Dustin Denzer Alyssa McDonald

Type of Monogenea Physical Characteristics Roughly ten millimeters long Six muscular suckers One pair of large hooks (Hamulus) Sixteen small hooks Definitive Host- Common Frog Lives in the bladder of Rana temporaria (Brown frog) Found in Europe Not a threat to humans

Eggs are laid when host begins mating. Eggs hatch days later in spawning pool. By this point tadpoles should be hatched and growing. Attaches to the gills of the host, internal or external. If Polystoma infects a young tadpole (external gill) it becomes neotonic (abnormal cycle).

Neotonic form produces eggs within days. These eggs then hatch within days in warmer water, by this time all tadpoles should be maturing. If it infects an older tadpole that is maturing (internal gill) it remains immature (normal cycle) Synchronizes reproduction and maturation with host.

Target Tissues: Primarily gills Appearance: Two to four eye spots; one pair of large anchor hooks; scallop-shaped head Size: Approx μm in length Movement: Free-moving, though anchor end often attached to fish tissue Egg-layer: pathogen of hatchery fish AmLE

Target Tissues: Primarily skin and fin Appearance: Two pairs of anchor hooks; v-shaped “head” Size: Approx mm in length Movement: Free-moving, though anchor end often attached to fish tissue Live-bearer; may be able to see fully-developed embryo with hooks inside adult

Loss of blood Erosion of epithelium Access for secondary bacterial or fungal infections Gill irritation stimulates excess mucous production Massive die-offs

Every 24 hours, 4-10 eggs are deposited by a single worm during the summer months Greater amount of eggs with increasing temperature Eggs need 4-5 days between 20° and 28° C for embryonation When temperatures drop this slows and eventually becomes completely suppressed Seems like a good thing, but really: The eggs don’t die, they will eventually hatch out in the spring when the temperatures warm up again, infected the young fish

Usually infect: trout, bluegills, and goldfish Massive infections are due to their rapid maturation It is possible to see several generations of worms within a single worm (Russian Doll arrangement) Young worms are unable to swim, but transfer isn’t hard within hatcheries because the next host is so close Control methods: Pesticide Rotonone, small volumes of aqueous aluminum and sulfuric acid