Question

⦁ Identify all of the sharks below using the dichotomous key provided.
1. A. Body kite-like in shape (if viewed from the top) .................................. Go to statement 12
B. Body not kite-like in shape (if viewed from the top) ............................ Go to statement 2

2. A. Pelvic fin absent and nose saw-like ...................................................... Family Pristiophoridae
B. Pelvic fin present .......…........................................................................ Go to statement 3

3. A. Six gill slits present ...........................................................................….. Family Hexanchidae
B. Five gill slits present ......................................................................…….. Go to statement 4

4. A. Only one dorsal fin ..........................................................................…... Family Scyliorhinidae
B. Two dorsal fins ..................................................................................... Go to statement 5

5. A. Mouth at front of snout…………..........……………………………………….…….… Family Rhinocodontidae
B. Mouth on underside of head ............................................................... Go to statement 6

6. A. Head expanded on side with eyes at end of expansion ……………….….. Family Sphymidae
B. Head not expanded .............................................................................. Go to statement 7

7. A. Top half of caudal fin about the same size as bottom half …………….... Family Isuridae
B. Top half of caudal fin different in size than bottom half ……….…………. Go to statement 8

8. A. First dorsal fin very long, almost ½ total length of the body….………… Family Pseudotriakidae
B. First dorsal fin regular length ……………………..................................…….. Go to statement 9

9. A. Caudal fin very long, almost as long as entire body ………………………... Family Alopiidae
B. Caudal fin regular length ................……………………………………………....…. Go to statement 10

10. A. A long needlelike point on end of nose ............................................... Family Scapanorhynchidae
B. Nose without long point ...................................................................... Go to statement 11

11. A. Orange fin absent ....................................……………………………………….…..... Family Squalidae
B. Orange fin present ..........................................……..................................... Family Carcharhinidae

12. A. Small dorsal fin present

Answer 1

this is kind of hard to explain but pick a shark, go to statement 1, if statement A is true follow the directions and go to statement 12, otherwise, if statement B is true, go to statement 2 like it says

then you'd follow the directions at the next statement until you get to the point where it says what kind of shark it is

Answer 2

for example, I'm going to pick shark 10, then using statement 1, it's body is not kite-like if viewed from above, so I go to statement 2

statement 2 --> shark 10 has a pelvic fin, so I go to statement 3

statement 3 --> shark 10 has 5 slits (I hope i counted correctly ;-;) so I go to statement 4

statement 4 --> it has 2 dorsal fins, so I go to statement 5

statement 5 --> mouth is on the underside, so I go to statement 6

statement 6 --> head is not expanded, go to statement 7

statement 7 --> top half of caudal fin is different in size (I think... I'm not 100% sure what they mean by this) go to statement 8

statement 8 --> dorsal fin is regular length --> go to statement 9

statement 9 --> caudal fin is long ---> Family Alopiidae ---> stop and pick another shark to classify

Answer 3

you need to know a bit of terminology regarding the fins to be able to answer this

Answer 4

@Pixel