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The parasite isopods of the family Dajidae:
Lushious parasites of planktonic crustaceans! |
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The Dajidae isopods are ectoparasites of shrimp, mysids, and euphausiids. The female of Oculophryxus bicaulis Shields and Gomez (1996) is unique in its attachment to the eyestalk of the euphausiid host. The well-developed antennae encircle the eye peduncles of the host.
Oculophryxus bicaulis parasites to the euphausiids Stylocheiron affine Hansen, 1910 and S. longicorne G. O. Sars, 1938. It is distributed in the South China Sea, California Current, and Gulf of Mexico. We believe this parasite species has a circumglobal distribution bucause its hots have a broad distribution (see map).
The female is larger than the male and has an aberrant morphology. The male parasites live attached to the posterior part of the female near margin of the marsupium. The female feeds by sucking blood directly from the head of the euphausiid. The female may castrate their hosts as none of the infected hosts had reached matutity.
They are cool animals, aren't they? |
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Shields, D.J. & Gomez-Gutierrez, J. (1996) Oculophryxus bicaulis, a new genus and species of dajid isopod parasitic on the euphausiid Stylocheiron affine. Hansen. International Journal for Parasitology, 26(3): 261-268. |
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Lateral view of Oculophryxus bicaulis female attached to the eye stalk of Stylocheiron affine. The male is usually find it in the marsupium of the female. The size of the female parasite is about 18% the euphausiid size. |
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Electron transmission picture of the antena of Oculophryxus bicaulis female attached to the eye stalk of Stylocheiron affine (top left panel). The female sucks body fluids from the euphausiids using a tubular mandibule (top right panel). In the lower left panel is showed a detailed view of the female's marsupium. The male is usually find it in the marsupium of the female (bottom right panel). |
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Oculophryxus bicaulis has been find in two euphausiids: Stylocheiron affine Hansen and Stylocheiron longicorne Hansen.
These species have several ecophenotypes in the Ocean Pacific and O bicaulis has been recorded in the following forms:
Host Species & ecophenotype Infested by O bicaulis
Stylocheiron affine
West Equatorial yes (N=1)
California Current yes (N=27)
East Equatorial yes (N=1)
Indo-Australian ?
Central no
Stylocheiron longicorne
Short form yes (N=1)
Long form yes (N=1)
Indian Ocean form ? |
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List of Dajidae species of the world:
Dr. Jeffrey Shields' home page |
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Morphology of the female of the isopod Dajidae
Oculophryxus bicaulis. The ventral view shows
the internal eggs (rigth top). |
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Back to euphausiid's web page |
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