Dichotomous Key/Cephalopoda

Dichotomous Key

Cephalopoda
Kingdom	Animalia
Phylum	Mollusca
Class	Cephalopoda

1

• External shell
  • Present - Nautiloidea
  • Not present - 2

2: Coleoidea

• Modified (or lost) arm pair
  • Arm pair IV - 3
  • Arm pair II - 4

3: Decapodiformes

• Cornea
  • Present - 6
  • Not present - 5

4: Octopodiformes

• Photophores
  • Present - Vampyroteuthis infernalis
  • Not present - Octopoda

5

• Shell shape
  • Horn-shaped - Spirula spirula
  • Other or not present - 7

6: Sepioidea

• Cuttlebone
  • Present - Sepiidae
  • Not present - 8

7

• Gladius
  • Present - Oegopsida
  • Not present - 10

8: Sepiolida

• Depressions on funnel locking-apparatus
  • One - Sepiolidae
  • Two, or apparatus fused - Sepiadariidae

9

• Adhesive organ on dorsal surface of mantle
  • Present - Idiosepiidae
  • Not present - Myopsida

10

• Branchial canals in gills
  • Present - 11
  • Not present - 9

11: Bathyteuthoida

• Buccal connectives attaching to border of arms IV
  • Dorsal border of arms IV - Bathyteuthidae
  • Ventral border of arms IV - Chtenopterygidae