Architeuthis dux

Much remains unknown about the early life history of Architeuthis, including mating, fertilization, egg laying, embryonic development, hatching, and most of the larval development process. Are the eggs laid in huge gelatinous masses or individually? O’Shea et al. (2022) recently described five paralarvae of A. dux (ML 6.7-8.8mm) collected in epipelagic waters off New Zealand and reviewed previous published accounts of small individuals attributed to Architeuthis. Two juveniles of Architeuthis have been described from specimens of 57mm ML from off Madeira Island, eastern North Atlantic, and 45mm ML from the eastern Pacific Ocean off Chile (Roper & Young 1972). Both were taken from the stomachs of deep-sea lancetfish (Alepisaurus ferox), and exhibited marked differences in body proportions suggesting that they may in fact represent two different species. The Atlantic specimen had arms as long as the mantle, while in the Pacific form the longest arms (II-IV) were about 60% of the ML; the Pacific specimen had tentacles less than half as long as the Atlantic form. These specimens when reported were an order of magnitude smaller than the previously known smallest architeuthid. Several further small specimens have been reported as architeuthids, but close inspection reveals them to belong to other families. One specimen reported by Toll and Hess (1981) as Architeuthis is a mature male at 167 mm ML, a remarkably small size for a true architeuthid. Most cephalopods are fast-growing animals. Some species of small, shallow-water forms reach sexual maturity in 6-8 months, and most species about which growth, age and maturity data are available reach reproductive capacity within 12-18 months. Many examined Architeuthis specimens have been mature, especially the females (which are much more abundant in collections). But the age at maturity of Architeuthis is not known with certainty and published estimates have varied widely, with most falling between 2-3 and 14 years (see Perales-Raya et al. 2020 for review). Even at the rapid growth rate expected in most cephalopods, achieving a mass of 500kg or more in fewer than 3 years would be impressive. Females produce enormous quantities of whitish to cream-colored eggs, about 0.5-1.4mm long and 0.3-0.7mm wide, depending on the stage of their maturity. One female had over 5kg (over 11 pounds) of eggs in her ovary--well in excess of a million eggs. As in most oegopsids, females have a single median ovary in the posterior end of the mantle cavity; paired, convoluted oviducts along which mature eggs pass, then exit through the oviducal glands; and large nidamental glands that produce quantities of gelatinous material. Whether the eggs are laid into a large gelatinous matrix, as in most of the large oceanic squids, e.g., ommastrephids and thysanoteuthids, or are released individually, remains unknown, although the large nidamental glands suggest the former method (Roper & Boss 1982 and new information). Males tend to reach sexual maturity at a smaller size than do females. The two ventral arms, arms IV, are reported to be modified (=hectocotylized) to transfer very long, thin, cylindrical packets of sperm, the spermatangia (erupted spermatophores), to the female. As in most other cephalopods, the single, posterior testis produces sperm that move into a complex system of glands that manufacture the spermatophores. These are stored in an elongate sac, Needham’s sac, from which they are expelled during mating. The Needham’s sac of fully mature males is packed with hundreds of spermatophores, each up to 15cm long. Needham’s sac terminates in the terminal organ, which is so elongate that it extends anteriorly beyond the mantle opening, sometimes through the funnel. While mating has not been observed and the exact role of the terminal organ is uncertain, some females have been found with spermatangia, the sperm-containing sacs of the spermatophore, embedded in the tissue around the bases of the arms and the head (Norman & Lu 1997). Males have also been examined with embedded spermatangia, although these may represent self-implantation during capture.