Members of the Ommastrephidae are small (about 10 cm ML) to large (about 100 cm ML), muscular squids that are often the dominant large squids in oceanic and, occasionally, neritic waters. A number of species are fished commercially.
Ommastrephid squids are among the strongest swimmers in the Cephalopoda. Some are commonly known as "flying squid" due to their ability to glide over the ocean surface as seen in the photographs.
Funnel/mantle locking-apparatus with an inverted T-shape.
Figure. Frontal views of the funnel/mantle locking apparatus. Left - Funnel component of Illex illecebrosus. Middle - Mantle component of Illex illecebrosus. Photographs by M. Vecchione. Right - Opened mantle cavity showing the funnel/mantle locking apparatus of Todaropsis eblanae. Drawing from Naef (1921-23).
Thick lateral funnel-adductor muscles connect lateral edges of funnel with head near its ventral surface. [These muscles are not homologous with the more superficial muscles of the Sepioidea which bear the same name.]
Figure. Ventral view of the funnel of Illex illecebrosus showing the strong lateral adductor muscles (arrows). These muscles are also seen in the drawing of Todaropsis eblanae above. Photograph by M. Vecchione.
Paralarvae (rhynchoteuthion stage) with fused tentacles (=proboscis).
The proboscis begins to split at the base usually around 3-4 mm ML. The split gradually increases until the proboscis has split completely in half to form the two tentacles at about 7-10 mm ML. The proboscis increases in size as the paralarva grows but at about 6 mm ML the proboscis begins to shrink in absolute size until the tentacles are formed. The small newly formed tentacles appear to be initially non-functional (poorly formed suckers) but grow rapidly (see Wakabayashi et al., 2002).
Figure. Rhynchoteuthion paralarvae. Left - Oral view, species unknown. Drawing modified from Naef (1921-23). Middle -Ventral view of Ommastrephes bartramii, 4 days old, living. Photograph by Y. Sakurai. Right - Ventral view of Sthenoteuthis oualaniensis, advanced, fresh. Photograph by R. Young.
Arms with biserial suckers.
Tentacular clubs with quadraserial suckers (club dactylus with eight sucker series in Illex).
Buccal connectives attach to dorsal borders of Arms IV.
Distinctive, slender gladius with primary conus.
Figure. Ventral view of the gladius of Todarodes sagittatus, immature, 120 mm ML. Drawing from Naef (1921-23).
Comparison of subfamilies:
Funnel- groove foveola3
Funnel- groove side pockets3
Distal protective membranes on hectocotylus
Carpal locking apparatus2
Ventral membrane enlarged subdistally
Present except Ornithoteuthis
Ventral membrane with thickened trabeculae
1Photophores difficult to detect in some species.
2Defined as presence of knobs and corresponding suckers with smooth sucker rings.
3Funnel grooves in Todarodinae and Ommastrephinae:
Figure. Ventral view of the funnel groove comparing modifications in two of the subfamilies. Drawing modified from Roper, et al. (1985).
The family is characterized by an inverted T-shaped funnel locking cartilage, biserial suckers on the arms, tetraserial suckers on the tentacular clubs (except Illex which has 8 rows of suckers on the dactylus), buccal connectives that attach to the dorsal borders of arms IV, photophores in some genera, and a muscular bridge anterior to the funnel locking cartilage which passes from the funnel to the ventral surface of the head. The inverted T-shaped funnel locking cartilage easily distinguishes this family from all others, even in the youngest stages. One genus, Symplectoteuthis, has the funnel mantle cartilages fused at a single point, but they are otherwise typical. Three subfamilies are currently recognized: Ommastrephinae, Todarodinae, and Illicinae. The Ommastrephinae is distinguished by the presence of a central pocket (foveola) and several side pockets in the funnel groove, and by the presence of photophores which are often deeply buried in the tissue of the mantle, head and arms. It comprises five genera: Ommastrephes, Symplectogeuthis, Dosidicus, Ornithoteuthis and Hyaloteuthis.
Although the family is very well characterized, placement of species with genera and subfamilies has, in some cases, been controversial. These controversies have often revolved around the importance of absence of a character (e. g., absence of foveola and side pockets from the funnel groove of Todaropsis, a feature shared with Illex) which, without adequate polarization, could be interpreted as a synapomorphy, a symplesiomorphy, or a convergent loss.
Figure. Phylogenetic tree of the Ommastrephidae. The three basal branches represent the three subfamilies. Figure based on Roeleveld (1988).
The relationships presented here are from the phylogenetic study by Roeleveld (1988). The relationships are based on a number of different structures but rely heavily on the structure of the hectocotylus. The lack of known relationships among outgroups makes rooting of the tree difficult. Not all workers agree with the subfamial placement of genera (e.g. Nesis, 1982/7; Wormuth, et al., 1998). The latter authors place Todaropsis next to Illex in the Illicinae.
Barcode of Life Data Systems (BOLD) Stats Specimen Records:246 Specimens with Sequences:226 Specimens with Barcodes:215 Species:22 Species With Barcodes:21 Public Records:149 Public Species:19 Public BINs:24