A biologist is using a dichotomous key to identify fish. 1. (a) Has a single dorsal fin ® 5
(b) Has a double dorsal fin ® 2
2. (a) One fin is spiny, the other is smooth ® 3
(b) One fin is not spiny or smooth ® 4
5. (a) Has small fin on back near tail ® 6
(b) Has no fin on back near tail ® 7
6. (a) Has barbs near the mouth ® Catfish
(b) Does not have barbs near the mouth ® 10
7. (a) Tail is asymmetrical ® 8
(b) Tail is symmetrical ® 9
10. (a) Scales are small ® Trout
(b) Scales are large ® Whitefish

What is the next step to take to identify a fish that has a single dorsal fin and no fin on the back near the tail?
step 5
step 2
step 7
step 6