Fiery Gonate Squid

Gonatus pyros

DESCRIPTION.—The mantle is slender; in almost all specimens examined, it is contracted and tapers gradually from a flaring margin to a posterior point. The mantle margin projects ventrally in the areas of the mantle locking-cartilages, but not dorsally. The mantle wall is moderately thick and muscular.

The fins are broad. A posterior “tail” is only slightly developed in the largest specimens. Free anterior lobes are present, and the lateral fin margins are rounded. The fins are very muscular, but are almost always damaged.

The funnel is free laterally and extends forward to about the level of the posterior edge of the lens. The funnel locking-cartilage has a long, straight sulcus which opposes a straight ridge on the mantle. The dorsal pad of the funnel organ has roughly the shape of an inverted V; the lateral arms are long and angled laterally. Small, median ridges are present near anterior ends of each of the lateral arms, and a small papilla lies at the blunt anterior apex. The ventral pads are roughly oval in shape.

The head is short and rounded. Its width generally exceeds that of the mantle. The eyes are large, and occupy the entire lateral sides of the head; an anterior sinus is present on each eyelid. Each “olfactory” organ is flaplike and located at the posterodorsal end of the second nuchal fold from the funnel. The 3 nuchal folds are very feeble and can be recognized only in the most perfectly preserved specimens. The nuchal cartilage is elongate and rounded at either end. It bears 3 longitudinal ridges; 2 are near the lateral edges of the cartilage, and one is in the median line. The median ridge has a narrow, central sulcus along its midline.

Arms II and III are moderately long and muscular; their length in specimens larger than 35 mm P.L. varies between 60–70% of the P.L. Arms I are shorter and vary between 50–60% of the P.L. Arms I–III appear to have had membranous or gelatinous swimming keels. Arms IV are nearly the same length at the lateral arms, but are more slender. Thin, broad, lateral keels are present along the entire lengths of arms IV. Arms I–III all have well-developed trabeculate, protective membranes; trabeculae and membranes are less developed on arms IV. The armature of the arms is in 4 series. On arms I–III, the marginal rows consist of small suckers that arise near the ends of the trabeculae; the medial 2 rows are composed of large, alternating hooks which are replaced by suckers at the arm tips. Arms IV have suckers instead of hooks in the medial rows. All of the arm suckers have similar dentition. On the distal part of the inner ring are long, pointed teeth that grade into smaller teeth laterally. The proximal margin is smooth. The total number of teeth in each ring varies roughly from 6–9. The marginal suckers of arms I–III are larger than the medial suckers of arms IV, while the marginal suckers of arms IV are smaller than the medial suckers. The usual number of suckers and hooks on the proximal half of arms I–III varies from 29–33, while on arms IV, in specimens larger than P.L. 34 mm, the half-arm count varies from 36–41.

The tentacles are long and robust. The tentacular clubs are short, expanded, and very complex. The club length varies from 20–25% of the P.L. The locking zone has 4–6 thick transverse lamellae; adjacent to each at the base of the medial end lies a large, smooth-ringed sucker, and alternating with these are rounded knobs. Proximally, this structure is marked off from the tentacular stalk by a large gap. Distally, the thick lamellae abruptly decrease in size; generally, the last two are rudimentary, but have typical suckers. Suckers of the dorsal-marginal zone converge into approximately 3 rows which pass around the central hook to merge with the suckers of the dactylus. Suckers in this group usually are absent at the proximal edge of the club, although occasionally they extend onto the stalk. In the median zone, a single, large hook lies near the center of the club and is followed distally by a hook of intermediate size and proximally by 3–4 small hooks. The distal hook is rarely joined by an enlarged sucker with a large median tooth. The small hooks decrease in size proximally and are occasionally preceded by a proximal series of suckers. The ventral-marginal zone consists of 3 or sometimes 4 longitudinal rows of suckers in its midportion, all of which are nearly the same size. This group of suckers continues onto the tentacular stalk not only as the marginal row, but also as a more medial, sligthly irregular series. Distally, this zone terminates opposite the large central hooks.

The largest suckers from the ventral-marginal zone have large, rather broadly separated, pointed teeth on the distal margin of the inner rings which grade into smaller teeth laterally. The proximal border is smooth. The total number of teeth in each ring is roughly 9–10. These suckers are approximately the same diameter as the suckers from the medial rows on arms IV. The suckers of the middle of the dactylus have similar dentition, but with sligthly fewer teeth. The suckers at the proximal end of the dactylus are numerous and not arranged in distinct rows. Slightly distally, they become aligned in 4 longitudinal rows. The suckers in a transverse series are nearly the same size proximally, but distally the suckers of the dorsal row are slightly smaller than those of the ventral row. The tip of the dactylus has a circlet of small, smooth-ringed suckers. The total number of suckers on the dactylus (excluding the circlet), the dorsal-marginal zone, and the ventral-marginal zone varies from 151–184.

The locking apparatus on the manus continues along the dorsal margin of the tentacular stalk proximal to the gap, but much reduced. The large lamellae on the manus are represented by relatively low rounded lobes which soon disappear; but they are much more apparent than in any of the other 3 local species of Gonatus. The marginal suckers and alternating knobs decrease in size proximally, and extend along, roughly, three-fourths of the stalk. The suckers along the ventral margins continue for about half the length of the stalk. The suckers in the latter series situated one-fifth of the tentacle length from the base of the club have a few broad, slightly pointed teeth on the distal margin of the inner ring. Almost all specimens have an additional series of suckers on the tentacular stalks which are continuous with the suckers of the ventral-marginal zone of the manus. This series closely parallels the suckers of the ventral margin on the stalk. This series is variable, but usually extends about three-fourths of the length of the marginal row, although it is most clearly present in the distal part. These suckers generally are arranged in a single row, an irregular single row, or occasionally an irregular double row. Sometimes, this series lies very close to the marginal row; more frequently, it is separated from the latter by a distinct gap and rarely contains the only suckers on the tentacular stalks that lie medial to the marginal rows. More commonly, additional suckers are scattered about the oral surface of the stalk. The number of suckers in the ventral row varies between 80–110% of those in the dorsal row. The number of suckers on the stalk between the marginal rows varies betwen approximately 50–125.

The thin buccal membrane attaches far up on the bases of the arms. It has 7 lappets and the connectives attach to the dorsal borders of arms I and II and to the ventral borders of arms III and IV.

A single, large, white photophore lies on the ventral surface of each eye. Each photophore is somewhat oval and covers the greater portion of the ventral surface of the eye. It is immediately distinguishable from the silver tissue surrounding the eye by its well-defined boundaries and its peculiar surface which seems to have many small pores.

Although the integument is damaged on all specimens, some indication of its color remains. The sides of the head and the aboral sides of arms II and III and, to a lesser extent, arms I, are covered by a brilliant silvery layer. This layer extends over the ventral surface of the head, but it is not as well developed there. It is not possible to tell whether or not this layer was present on the lateral surfaces of the mantle. All of the head, arms, fins, and mantle (including the silvery layers) appear to have been covered by brownish red chromatophores. The buccal membrane lacks pigmentation except for a few chromatophores on its outer surface.

Hooks on the arms are present at a P.L. of 17–22 mm; the distal hook on the club begins to develop at a P.L. of 18–23 mm; the median hook at a P.L. of 15–18 mm; and the proximal hooks at a P.L. of 21–26 mm. A spindle-shape liver lying oblique to the body axis is present in the larva.

TYPE LOCALITY.—33°37′ N, 118°26′ W, eastern North Pacific Ocean.

LOCATION OF TYPE.—University of Southern California. U.S.C. Hancock collections, AHF Cephalopod Type No. 5.

Gonatus pyros, the fiery gonate squid, or fiery armhook squid, is a species of squid within the family Gonatidae. The distribution of the species is in the central and eastern North Pacific from the Aleutian Islands to Baja California, where it lives at depths of 563 to 667 meters in oceanic environments. Their planktonic paralarvae are usually found at depths of 200 to 300 meters. High abundances occur over continental slopes in the summer. It grows to lengths of 125 millimeters.

Gonatus pyros currently has no conservation measures towards it, and more research is required to fully understand its distribution, population, and potential threats that may effect the species. For now it has been assessed as 'Least concern' by the IUCN Red List.

epi-mesopelagic