Siphonostomatoida

Article By:

McLaughlin, Patsy A. Shannon Point Marine Center, Western Washington University, Anacortes, Washington.

Last reviewed:June 2020

DOI:https://doi.org/10.1036/1097-8542.625850

An order of Copepoda, whose members are parasites of marine and freshwater fishes or a variety of invertebrate hosts. In fact, it is estimated that 67% of the copepod parasites of fishes belong to the order Siphonostomatoida. Their obvious success in the parasitic mode of life appears at least in part to be a result of two morphologic adaptations. The first is the modification of the buccal apparatus (mouth and oral appendages). The siphonostomatoid mouth forms a tube or siphon through the partial or complete fusion of the labrum (“upper lip”) and labium (“lower lip”) around the esophageal opening. The resulting mouth cone has a small opening near the base through which the mandibles are free to enter. The mandibles themselves are styliform (see illustration) and may or may not be armed with denticles. The maxillae are subchelate or brachiform, superficially resembling a human arm, and serve as the appendage for attachment to the host. The second adaptation is the development of a frontal filament, which is a larval organ of attachment. In those siphonostomatoids that possess a frontal filament, the brachiform second maxilla may be used to manipulate the frontal organ; in some species, fusion of those two structures forms the attachment structure. See also: Copepoda; Parasitology

The content above is only an excerpt.