Bathyteuthis numerosa

This species is found in the northwestern Atlantic Ocean and the northern Gulf of Mexico.

1.  The head is short and wide with large eyes.
2. Arms:
   1. Long and attenuate.
   2. Arm base photphore present on arms I-III of adult female and one juvenile; not present on another juvenile examined.
   3. Slight, wavy trabeculae present with minimal webbing between arms.
   4. Arm suckers extremely numerous on all arms (~164/arm), starting biserially at arm base and becoming densely clustered toward arm tip.
   5. Arm sucker teeth truncate with 8 teeth per inner ring.
3. Tentacles are long and thin but were borken before club.
4. Buccal connective attachments are DDVV and there are 5-7 buccal suckers per lappet.

Figure:  B. numerosa. A) no arm phtotophores; B) arm photophores (adult female); C) arm suckers; D and E) buccal lappet suckers. (Drawings by P. Nolan in Judkins et al. 2020, Bulletin of Marine Science).

The presence/absence of arm photophores within this species is interesting and can most likely be attributed to two possibilities.  This may be a dimorphic trait with females exhibiting the arm base photophore while males do not. Another possibility may be that as the two juveniles examined were only 3 mm different in ML, it may suggest that it is at this developmental stage where the arm base photophores develop.  Additional male and females of juvenile and adult stages are needed to confirm either of these theories.