Onychoteuthis compacta (Berry, 1913)

Introduction

O. compacta appears to be the most common of the three species of Onychoteuthis found in Hawaiian waters. It is most easily identified by characteristics of its pigment pattern. Juveniles and subadults have a distinctive region on the posteroventral surface of the mantle that lacks chromatophores.

Characteristics

1. Tentacular club
   1. Club without marginal suckers in subadults.
   2. Distal 4 or 5? fully-formed hooks in ventral series with spikes (see arrow) that protrude through the skin.
      image info image info

      Figure. Oral views of tentacular club of O. compacta. Top - Original drawing by Keiko Hiratsuka Moore, National Marine Fisheries Service. Distal portion of club showing hook spikes (arrow), preserved. Photograph by R. Young.

      Scanning electron micrographs of the hooks can be seen here.

2. Mantle pigmentation
   1. Triangular-shaped region on the postero-ventral mantle lacks chromatophores.
      image info

      Figure. Ventrolateral view of the mantle of O. compacta, preserved, showing pigmentation, Hawaiian waters. Photograph by R. Young.

Comments

Life History

Paralarvae of O. compacta are easily identified by the arrangement of their chromatophores. At 3-4 mm GL: A simple band (i.e., a single, straight line) of chromatophores is present along the free ventral margin of the mantle; a group of chromatophores is situated well posteriorly on the ventral mantle and two large chromatophores are located ventrally opposite the fins. At 6 mm GL: Two pairs of chromatophores are present on the ventral mantle adjacent to the fins. A small patch of chromatophores is present dorsally at the posterior convergence of the fins. At 9 mm GL: Two parallel rows of small chromatophores are located dorsally stradling the midline of the mantle. At 12-16 mm ML: Chromatophore numbers increase dramatically. At 18 mm ML: The subadult chromatophore pattern can be recognized.

image info

Figure. Ventral and dorsal views of paralarval and juvenile O. compacta. A - 2.3 mm GL. B - Ventral view of a common condition in this species: head retracted within the mantle cavity, 4.8 mm GL. C - 4.1 mm GL. D - 8.9 mm GL. E - 18.5 mm GL. The bar is 1 mm. Drawings from Young and Harman (1985).

References

Berry, S. S. 1913. Some new Hawaiian cephalopods. Proc. U. S. Nat. Mus. 45: 563-566.

Kubodera, T., U. Piakowski, T. Okutani and M. R. Clarke. 1998 Taxonomy and zoogeography of the family Onychoteuthidae. Smiths. Contr. to Zoology, No. 585: 277-291.

Young, R. E. and R. Harman. 1985. Descriptions of the larvae of three species of the Onychoteuthis banksii complex from Hawaiian waters. The Veliger, 29: 313-321.