As with other Oplophorus species, O. spinosus has a long rostrum with many spines on both the dorsal and ventral surface. Note the well-developed eye as well.
This right-side view of the anterior (first 3) abdominal segments (the posterior thorax is at the right side) shows that the second abdominal segment does not have a large posterior mid-dorsal spine. The large eggs can be seen attached to the pleopods.
This right-side view of the posterior abdominal segments show the large posterior-pointing mid-dorsal spines on several of them. Abdominal segment 3 is at the top right, then segments 4,5,6, and the base of the telson is visible at the bottom left. Note that segment 6 is not dorsally carinate.
Dorsal view of the rear abdomen and telson. The rightmost segment is abdominal segment 5. Segment 6 is below the posterior spine from segment 5. To the left are the uropods and telson.
In O. spinosus there is no sharp tooth on the posterior margin of the ventralcarapace. In this view of the animal's right side, the ventral margin of the carapace plus the pereopods can be seen to the right and the first abdominal segment with pleopods and several eggs is visible to the left. The posterior margin of the ventralcarapace has an acutely rounded corner but no sharp tooth.
A female Oplophorus spinosus carrying eggs, carapace length 1.5 cm, captured in midwater off Hawaii in 1996. In real life this species would be partly pinkish-red and partly transparent. The specimen above has been preserved in formalin. Several eggs have dropped off the pleopods. (Photo by: Dave Cowles, 2012 )