Echinoteuthis Joubin, 1933

Introduction

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Figure. E. atlantica, in situ photograph from an ROV of NOAA's R/V OKEANOS EXPLORER near the ocean floor at 866 m depth.

Only one species (E. famelica) in Echinoteuthis is well known. Each species, of those known from subadults, is thought to occupy a different ocean: E. glaukopis - Indian Ocean; E. famelica - Pacific Ocean; E. atlantica - Atlantic Ocean. Two species (E. tyroi - Indian Ocean, and E. danae - Atlantic Ocean) are known only from paralarvae and may belong to the known species from their area.

Fig. Same squid as above. Arrow points to apparent window in the squid's eyelid over its photophore.

Brief diagnosis:

Species of Echinoteuthis ...

• with large eyelid photophore.
  
• without other photophores.
• Presumably with tubercules in paralarvae.
  

Characteristics

1. Arms
   1. Arms III distinctly longer than arms I.
      
      
2. Tentacles
   1. Little variation in sucker size over most of tentacular club.
   2. Club suckers large; reach a diameter of 0.3-0.4 mm in large squid.
      
      
3. Head
   1. Funnel pocket present.
      
      
4. Funnel
   1. Funnel locking-apparatus ear shaped with large tragus and weak antitragus; posterior margin not undercut.
      
      
5. Fins
   1. Fins slightly longer than broad (except, apparently in E. glaukopis).
      
      
6. Tubercules
   
   1. Tubercules absent from integument except in paralarvae.
      
      
7. Photophores and pigmentation
   1. Large round to oval photophore located on the anteroventral margin of each eyelid.
   2. No ocular or integumental photophores.
   3. Most pigment in closely-spaced chromatophores.
      
   

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   Figure. Lateral view of the head of E. famelica showing the size of the eyelid photophore (arrow). The rather large eyelid photophore (length ca 2.3% of ML) may be hidden by pigmentation. Photograph by R. Young.

Comments

E. glaukopis is known only from the holotype which is small (37 mm ML including tail) and has lost all trace of pigment. At present its geographical distribution is the only feature known to separate it from the other two species. E. atlantica is also poorly known, however, it has relatively large trabeculate protective membranes on the tentacular clubs which separates it from E. famelica. The presence of E. danae and E. tyroi as members of Echinoteuthis has not been clearly established.