The voucher sheet project

Eyes Under Puget Sound

This month, we’re taking a break from our regularly scheduled critter post to tell you about an exciting venture we’ve been working on here in the benthic lab: the voucher sheet project.



Says, “WA State Department of Ecology Benthic Invertebrate Voucher Sheet.” Sections: Nomenclature, Distribution, Diagnostic Characteristics

The first page of a voucher sheet for Lucinoma annulata.

Since 1989, our Marine Sediment Monitoring Team has collected over 1,200 different types of sediment-dwelling invertebrates (also known as the benthos) from Puget Sound. As the team’s taxonomists, it is our job to put a name to each little face! We use several methods to be sure we have the names right, one of which is referencing voucher sheets. A voucher sheet is a short document that contains descriptions and photos of each species.

Sort it out 

It all starts when we sit down at our microscopes and open up jars containing hundreds of tiny preserved animals from our monitoring work in Puget Sound. Each jar gets dumped into a dish, and the animals are “morphotyped” — sorted into piles of similar-looking species based on their physical characteristics. Some species are distinct, and we recognize them right away. Others require delving into books, journals, online references and any other bits of information we can find in order to unravel the mystery of their identities.

Triptych: dish of critters, scientist at microscope with eyedropper and small jars, a gathering of small jars with critters inside

LEFT: A jar of marine worms gets emptied into a dish to await identification.

MIDDLE: In the process of morphotyping.

RIGHT: The completed sample, identified and labeled by species

Detective work  

Searching for taxonomic literature takes a LOT of time, and many references don’t contain illustrations. We’ve set out to help solve this problem by creating a set of Ecology publications called Benthic Invertebrate Voucher Sheets. It’s a large undertaking — we’ve completed 50 and have many more in the works!

The actual sheet that this image depicts is available from

A completed voucher sheet for the ostracod Euphilomedes carcharodonta.

What's in a voucher sheet, exactly?

Four delicate-looking worm feet shaped like pale flowers with one pointy appendage each and clumps of light brown straight hairs.

A close-up of the feet of the marine worm Cheilonereis cyclurus shows the tiny hairs and other features that make it distinct.

After we do our review of the literature, we create a voucher sheet that includes a basic classification, a general description and most importantly, a list of diagnostic characteristics which set that species apart from other similar-looking species. Using cameras attached to our microscopes, we take photographs of these diagnostic characteristics, even features as teeny as the hairs on a worm’s foot! These high-quality images illustrate exactly what to look for when we examine a specimen.

Benefits for Puget Sound and beyond 

By generating accurate data on what species are present in our samples, we can detect changes in the benthos over time as they respond to environmental stressors like those associated with climate change and pollution.

Scientist peers into microscope, and large image appears on computer monitor to the left of her.

Dany uses a microscope and attached camera to take a photo of a marine worm in the family Ampharetidae.

Voucher sheets not only help us correctly identify the critters we monitor, but they will also help other scientists doing similar work. Most species we collect aren’t limited to our region — many can be found all the way from Alaska to Mexico.

Scientists working in other regions can access our voucher sheets to help them correctly identify the invertebrates they collect. This is one way to improve taxonomic standardization — that is, making sure animals are identified the same way by taxonomists working in different areas — and expand the body of knowledge about our valuable biological resources.