As in Sandalops, species of Taonius go through a stage while in upper mesopelagic depths, in which the stalked eye has a nearly tubular shape (Young, 1975). The bottom of the eye is covered by two large photophores, one of which is strongly bilobed.
Figure. Ventral-oblique (left) and ventral (right) views of a tubular eye of a juvenile T. pavo, off Hawaii. Photograph by R. Young.
Figure. Dorsal view of a young Taonius (left) and a dorsal view of the anterior end of this squid (right), taken off Florida from a submersible of the Harbor Branch Oceanographic Institution. The eyes are just beginning the transition to a hemispherical shape. Large photophores appear to cover he posterior surface of the eyes. Photographs taken by E. Widder/HBOI.
Paralarvae of T. pacificus from Hawaiian waters have been identified. they are distinctive among cranchiid paralarvae from these waters in the near lack of chromatophores.
Figure. Paralarvae of T. pavo, Hawaiian waters. Thumbnail (far left) - Illustration shows relative sizes of the two paralarvae. Left - Ventral view of a 4.9 mm ML paralarva. The dotted circle in indicates the position of the digestive gland. The adjacent inserts show (1) a side view of an eye and (2) a dorsal view of the fins. This paralarva has no chromatophores. Right - Ventral and dorsal views of a 14.5 mm ML paralarva. This paralarva has one chromatophore on the dorsal and one on the ventral surface of the head and a few chromatophores on the aboral surface of each tentacular club and one at the base of each tentacle but none on the mantle. Also note the small size of the tentacular club and the shape of the fins. The scale bars are 1 mm. Drawings by R. Young.
No one has provided updates yet.