Conus okhotensis

Conus okhotensis

(Dall, 1893)

Descrizione :

Shell short, stout, solid, of about eight whorls ; spire low and rounded, suture appressed, with a few obscure spiral striae in front of it; shoulder of the shell rounded; sides smooth, hardly striated even over the canal, aperture rather wide, outer lip straight, sutural sinus shallow; pillar sismlpe, slightly twisted at the end; lon. of the shell 50 mm.; lat. 35 mm.

A young and an adult specimen were presented by Dr. Stimpson.

This species is not unlike Conus californicus on larger scale, and belongs, as well as can judged in absence of color markings, to a group (Chelyconus) which is most abundantly represented in the Moluccas and on the shires of Africa. There does not appear to be at present any closely related species on Japanese coasts, but Conus fulmen and Conus pauperculus are found in that regione and would in a general way be associated with it. Among the recent species in the National Museum, Conus glaucus from the Moluccas presents the closest parallel in form and conchological characters.

In the larger of the two fossil specimens a faint indication of what might be taken as traces spirally disposed color marks is perceptible, but these are not sufficiently distinct to permit of a dogmatic assertion the they are traces of color and not an incident of mineralization.

The name derives from Okhotsk sea.

Assuming a constant seawater δ 18O of -1.5‰ (Lear et al., 2000), including latitudinal correction (Zachos et al., 1994), oxygen isotope data yield mean annual temperatures of 19.3°C and 23.5°C and a mean annual range of temperatures of 19.8°C and 11.0°C for Alaska and Kamchatka, respectively. These temperature ranges are comparable to those of modern subtropical (40°N) mixed-layer waters, which implies significant warming episodes at high North Pacific latitudes during the peak of the MMCO. The variations in isotopic composition and inferred temperature ranges, as well as patterns of stratigraphic occurrence, imply that warm surface waters of the MMCO were not persistently present in high North Pacific latitudes, as they were at low latitudes. Instead, relatively short-term incursions of warm surface waters from the subtropical western Pacific episodically introduced warm-water mollusks into this generally cooler region ⁽²⁾.


Conus okhotensis MO 4789a mm. 50 x 35 Miocene Smithsonian United States National Museum	Conus okhotensis mm. 50 x 35 Image courtesy of the Smithsonian Institution Specimen Catalog Number: USNM MO 4789a Specimen GUID: http://n2t.net/ark:/65665/3594c27b9-a2af-4e02-b011-dd76bbd38084 Photo credit: Holly Little

Conus okhotensis mm. 50 x 35 Image courtesy of the Smithsonian Institution Specimen Catalog Number: USNM MO 4789a Specimen GUID: http://n2t.net/ark:/65665/3594c27b9-a2af-4e02-b011-dd76bbd38084 Photo credit: Holly Little

Conus okhotensis Image courtesy of the Smithsonian Institution Specimen Catalog Number: USNM MO 4789b Specimen GUID: http://n2t.net/ark:/65665/3594c27b9-a2af-4e02-b011-dd76bbd38084 Photo credit: Holly Little In the rear image of this specimen, two rounded spots similar to those present in Conus glaucus are clearly visible