Giant Squid Taxonomy
Class Cephalopoda

NOMENCLATURE IDENTIFYING CHARACTERISTICS
Kingdom: Animalia  
Phylum: Mollusca
  1. Soft body

  2. Siphon (funnel)

  3. Shell (may be internal or non-functional)

  4. Radula* often present

    *The radula is a chitinous ribbon (with rows of teeth) that cover a tongue-like muscle in the cephalopod mouth. It is used to drill holes through shells and shove food down the throat.

Class: Cephalopoda
  1. Bilaterally symmetrical

  2. Crown of circumoral (around the mouth), mobile appendages bearing suckers or hooks (except in Nautilus)

  3. Bipartite (two-part), chitinous jaw apparatus that looks like a parrot beak

    Diagram of squid beak

    and a chitinous radula (band of teeth) overlaying the tongue-like musculature

    Photograph of squid radula

  4. Well-developed nervous system and eyes

  5. A funnel for expelling waste, ink, eggs, and providing jet-propulsion

  6. Rapid color change made possible by chromatophores (elastic pigment sacs) and iridocytes (reflective plates) in the skin

  7. Usually with calcareous (calcium carbonate) shell

    1. coiled, chambered, as in Nautilus

      Diagram of Nautilus
    2. straight, chambered like fossil and internal shells

      Diagram of fossil shell
    3. chalky, layered cuttlebone of cuttlefish

      Diagram of cuttlebone

    4. gladius (pen) made of chitin (like a shrimp shell) of squids

      Diagram of gladius made of chitin

    5. Absent or rudimentary (tiny shell that does not do anything but tells us that the ancestors had shells, like the legs of boa constrictors) stylets of octopods

    Diagram of stylets of octopods

Subclass Coleoidea
  1. Calcareous, chitinous, or cartilaginous shell (if present) internal in a special sac inside the body

  2. Tube-like funnel

  3. Only 8-10 outer circumoral appendages, with suckers (at least in the young)

  4. One pair of gills
Order Teuthoidea
  1. 10 circumoral appendages, the fourth pair (tentacles) contractile (able to be pulled back toward the body) but not retractile (able to be pulled back into the body)

  2. Suckers with a horny ring, often with hooks

  3. Gladius chitinous, rod or feather shaped

  4. Posterior fin lobes fused

    Diagram of fin lobes

  5. Suckers or hooks stalked

    Diagram of suckers or hooks stalked
Suborder Oegopsida
  1. Eyes open, no membrane

  2. Gonoducts paired

  3. Hooks present in many groups

    Diagram of squid hooks

  4. No suckers on buccal lappets**

    Diagram of squid without suckers on buccal lappets

    **Buccal lappets are small triangular flaps that support the buccal membranes that hold the mouth in place; buccal lappets sometimes bear suckers.

Family Archieteuthidae
Genus Architeuthis
  1. Very large (to over 18 meters or 60 feet; the mantle can exceed 2 meters)

  2. Eyes huge, volleyball size, no eyelid sinus

  3. Tentacles very long, up to 2 to 3 times the length of the body and arms

  4. Tentacular club, narrow with four rows of large suckers on manus, and many rows on carpus

  5. Concave medial (toward the middle) posterior (toward the tail) borders of fins

  6. Carpal knobs in cluster (fixing apparatus) alternate with carpal suckers; very numerous; sucker/knob pairs extend far proximally on stalk

  7. Fin length occupies about posterior quarter of the mantle and tail


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