Student Stuff
What is a key?
A key is a device that aids in the identification of an organism. Keys are commonly found in scientific papers.
- Sample scientific paper title page (12k PDF)
- Sample scientific paper key (20k PDF)
Are there different types of keys?
Yes, there are many types of keys. Some just contain text, but others include images (visit the fish key on the AMOL site). In more recent years computer-based keys that often require special software have become popular (view crustacea.net and FaunaKeys).
What is a dichotomous key?
The most commonly used key in scientific publications is called a dichotomous key. This type of key requires users to choose one of two alternatives at each step. Each pair of choices is called a couplet. Each choice either gives the name of the organism or directs the user to another couplet further down in the key. Some keys contain many couplets.
Identify a fish using a key.
The simple key below contains only two couplets. It can be used to identify the three species of bullseyes that occur in the Sydney region.
Try to key out the fish in the image. If you don't know the names of the fins of a fish you can view the fish figure. More information on fish terminology is available in the glossary.
View larger image.
| Couplet 1 | |
|---|---|
| The body has bold brown stripes on the sides. |
You have keyed out a Common Bullseye.
Check if you are correct. |
| The body does not have bold brown stripes on the sides. | Go to couplet 2 |
| Couplet 2 | |
|---|---|
| The dorsal, anal and caudal fin tips are black (view fish figure with fins labelled). The body is grey above and yellow-bronze on the sides. |
You have keyed out a Black-tipped Bullseye/.
Check if you are correct. |
| The dorsal, anal and caudal fin tips are not black (view fish figure with fins labelled). The body is silvery to bronze often with a diffuse brown bar behind the gill cover. |
You have keyed out a Small-scale Bullseye.
Check if you are correct. |
