Dichotomous Keys

Our Example: A Shark

Shark/Skate/Ray Classification Example: Great White Kingdom Animalia Plylum Chordata Class Chrondrichthyes (Cartilaginous fish) Order Lamniformes (Mackerel sharks) Family Isuridae (White shark, 2 mako, longfin, shortfin) Genus Carcharodon (Greek=big tooth) Species carcharias

Sharks Use this labeled diagram to understand the terms needed to identify a shark.

Sharks key 1A Body shaped like a kite if viewed from the top-go to statement 12 1B Body not shaped like a kite if viewed from the top-go to statement 2

2A Pelvic fin not present and nose shaped like a saw ..............................Saw shark 2B Pelvic fin present

3A Has six gill slits...................Cow shark 3B Has five gill slits

4A One dorsal fin..........................Cat shark 4B Two dorsal fins

5A Mouth at the front of the head rather than back along underside of head..............................Whale Shark 5B Mouth back along underside of head

6A Head shaped like a T with eyes at ends of T..............................Hammerhead Shark 6B Head not shaped like a T

7A Top half of caudal fin same as bottom half 7B Top half of caudal fin different from bottom half

8A First dorsal fin very long-almost half the length of the body…… 8A First dorsal fin very long-almost half the length of the body…….False Catsharks and Gollumsharks 8B Smaller first dorsal fin length

9A Very long caudal fin, almost as long as whole body........................Thresher shark 9B Normal length caudal fin ……….

12A Has small dorsal fin near tip of tail......Skate 12B No dorsal fin near tip of tail.....Stingray

Take a piece of looseleaf and number it 1-14 Use the class handouts to help you identify the Family names of the sharks on the handout Do not write on the class set-answers will only be written on your looseleaf

Answers: 1.) Rajidae 2.) Aloplidae 3.) Pristophoridae 4.) Carcharhinidae 5.) Scyliorhinidae 6.) Rhinocodontidae 7.) Isuridae 8.) Squalidae 9.) Dasyatidae 10.) Scapanorhynchidae 11.) Pseudotriakidae 12.) Hexanchidae 13.) Sphyrnidae 14.) Mobulidae