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When we asked Kefyn Catley how he thinks students shouldgo about identifying their arthropod specimens, he said,"That’s the 64,000-dollar question."

Identifying arthropods is a challenge, even to Kefyn, who spends his days iden-tifying Australian ground spiders at the American Museum of Natural History.He also writes identification keys, which are used to classify specimens downto the species level. This sort of work is called systematics.

"Systematics deals with species," Kefyn explained. "The unit we study is thespecies, not populations or individual organisms." But identifying an organismto species can be very difficult, he said, even for experienced scientists. Kefynthinks it is more realistic for students to group arthropods by order and try toidentify them further by families.

Kefyn recommends putting everything that has been collected into alcohol,except butterflies and moths. Most will be dried and pinned later on, but soft-bodied specimens, such as spiders and caterpillars, must be kept in alcohol, hetold us. Then the sorting can begin.

Identification involves a series of steps, Kefyn explained. "Systematists beginwith the largest classification—the phylum Arthropoda—and keep narrowing itdown—through subphylum, class, order, family, genus, until they get to species.You may not get as far, but the procedure is the same," he said.

"Start by making a very gross first cut: separating things with wings from thingswithout wings. Next divide those into very basic groups: beetles, ants, flies,wasps, for example," he said. Do not be surprised if you have a lot of beetles,Kefyn mentioned as an aside, since beetles are the largest group of organismson the planet.

He advised using a picture key such as is found in many field guides or asking

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a local museum or naturalist to recommend a key to arthropods most likely tobe found in your area. When you use such a key, you will be sorting accordingto appearance, or morphospecies.

"Basically, you’re eyeballing your specimens, looking at the differences andsimilarities. Sort your specimens according to shape, color, number of legs,and any other differences you can discover, and see how many groupings(what scientists call taxa) you come up with and how far you can take it," hesuggested.

"If you are able, for example, sort all the things that appear to be beetles. Nextseparate the long, narrow beetles from the round beetles. Then take a closerlook at the long, narrow beetles and see characteristics that some share, likethe same type of antennae or the shape of their wing covers. This is the type ofprocess of elimination that scientists use all the time to group organisms. Indoing so, you may be sorting beetles into families, or even genera, withoutknowing it. This first step can take place by just using your powers of obser-vation—you don’t even need a key," he said.

"Some students may want to specialize in a particular group," Kefyn suggest-ed. "Some might want to tackle the bees, others might take on the ants. Thatway you’ll end up with experts in the class who can share their knowledgewith others, which is what entomologists do all the time."

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