Visit the
Molecular Expressions Website

Photo Gallery
Silicon Zoo
Chip Shots
Screen Savers
Web Resources
Java Microscopy
Win Wallpaper
Mac Wallpaper
Custom Photos
Image Use
Contact Us

Oblique Digital Image Gallery

Fish Louse

Fish lice are ectoparasites that infest marine and freshwater fishes. Unlike other blood-sucking invertebrates bearing the common name of louse, the fish louse is more closely related to lobsters, shrimp, and water fleas than they are to insects such as the human head or body louse. However, in an analogous fashion to true lice, members of the crustacean genus Argulus pierce the skin and inject digestive enzymes into the host with a highly modified mouthpart known as a stylet. Subsequently, the parasitic insects then suck out blood, mucus, and partially digested body fluids.

Although the fish louse poses no health threat to humans, it is of economic importance because their presence makes marketing a fish catch nearly impossible. Famous for their tenacious hold on a host fish's skin or gills, fish louse use small spines, hooked appendages, and a pair of large ventral suckers to latch onto their prey. Argulus species are known to travel thousands of miles during massive fish migrations, sometimes at impressive swimming speeds. Fish lice are also capable of moving very quickly on hosts and can often be observed without magnification crawling over their skins.

The life cycle of the fish louse is near perfectly adapted to the episodic or seasonal appearance of migratory fishes. Male and female lice mate while clinging on the host fish. After mating the fertilized female drops off to lay her eggs on aquatic plants and other submerged substrates. With 500 eggs in a strip and a life cycle that lasts anywhere from 40 to 100 days, populations of fish lice can rapidly escalate. This is particularly worrisome for aquaculturists and others managing contained fish populations in ponds, aquaria, or hatchery raceways.

Contributing Authors

Cynthia D. Kelly, Thomas J. Fellers and Michael W. Davidson - National High Magnetic Field Laboratory, 1800 East Paul Dirac Dr., The Florida State University, Tallahassee, Florida, 32310.



Questions or comments? Send us an email.
© 1995-2022 by Michael W. Davidson and The Florida State University. All Rights Reserved. No images, graphics, software, scripts, or applets may be reproduced or used in any manner without permission from the copyright holders. Use of this website means you agree to all of the Legal Terms and Conditions set forth by the owners.
This website is maintained by our
Graphics & Web Programming Team
in collaboration with Optical Microscopy at the
National High Magnetic Field Laboratory.
Last Modification Friday, Nov 13, 2015 at 02:19 PM
Access Count Since September 17, 2002: 12858
Visit the website of our partner in introductory microscopy education: