More Aquatic Insects of Montana and Wyoming

Crawling water beetle

Haliplus from Niobrara Conservation District.

Earlier, I promised to follow up with some discussion based on some of my Aquatic Insect photographs.

Technical mumbo-jumbo

I like this photograph. It is a composite image of about 20 photographs–each taken at a different depth of field–then integrated using image analysis software. I took it while working on the Wyoming Educational Benthic Imaging project. During the project I worked for EcoAnalysts, but the budget required much of my personal time (nights and weekends)for, therefore i specifically retained the artist’s copyright, while allowing limited copyrights to both EcoAnalysts Inc. and the Wyoming Association of Conservation Districts.  If you are interested in using these pictures, please write me and I will provide the necessary permissions–Just be sure to give credit where it is due 🙂

About the Critter

The subject is  Haliplus sp., a haliplid beetle (Coleoptera: Haliplidae). The common name for this family of beetles is the “crawling water beetles”.

In life, when you find one of these tiny guys (~2 mm) they usually appear to be frantically running along the bottom of a pool or your collection jar. Although they “crawl,” they appear to do so at great speed, frantically.  Definitely distinct from the slow methodical crawling of some of the damselflies or dragonflies, as well as from the smooth, multidimensional swimming of Dytiscids, Noterids, and Hyrophilids.  The adult haliplids push themselves downward as they swim which helps them disappear in to the fine sediments that are often collected with them.

lateral view of Haliplus sp.

One of the things that make haliplids unique is that they breathe air from an air bubble that they carry around with them.  Of course, other beetles (e.g., Dytiscids, Hydrophilids), and even some hemipterans (e.g., Corixidae, Notonectidae) also breathe air from bubbles carried around with them. However, the method of retaining the bubble is unique from all other groups of aquatic insects.  Halipidae are united by the morphological expansion of the rear coxae (think hip joints) into large flat plates, which hold a portable air bubble against the body (see above). This is one of the first key characters in many keys to identifying aquatic beetles, and if you’ve never seen it, the text can be confusing. Fortunately, a picture is worth a thousand words and once you see it you will never mistake any other feature for the expanded coxal plates of  the Haliplidae.  Most photographs of this feature exhibit the full-on ventral view– which is useful and shows the lovely sculpture of each plate (bottom)… but it is hard to appreciate the role the feature in respiration from this view.  For this reason, i really like my oblique angle shots (above).

A number of years ago I saw a film made of one of these beetles feeding before. i think it was by Win Fairchild or one of his students. the mouth parts acted like a little sewing machine pulling filamentous algae through like thread… their were spines on the mouth parts that were spaced appropriately for size of some filamentous algae. the spines pierced each cell, and sucked the juices out… so the thread of algae went in green, and came out empty clear cells…. very efficient.

Well that’s all the time for now… if you’d like to discuss… please post a comment. or use my contact page.

Ventral Peltodytes

Standard ventral view

The vental view shows how plates from below.

Tags: , , , , , ,

Comments are closed.