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The bigfin reef squid Sepioteuthis lessoniana is a neritic species widely distributed in coastal waters of the Indo-Pacific region and is of interest to fisheries for its high commercial value. Squid samples were collected from Keelung (KL) and Penghu (PH), around northern Taiwan from October 2012 to September 2013. A total of 949 squid were examined, and 620 squid were aged using statoliths. The age range of the squid in KL (55–183 days) was similar to that in PH (77–186 days). The squid hatched almost year-round, except in January and December in KL. Two seasonal cohorts were identified: a spring cohort (hatched in March to May) and an autumn cohort (July to October). Concentrations of nine trace elements in statoliths were analysed using solution-based inductively coupled plasma mass spectrometry (ICP-MS). Significant differences in Fe/Ca, Cu/Ca and Sr/Ca were found between the two locations, while significant differences in concentration ratios of Sr/Ca and Ba/Ca were noted between the two seasonal cohorts. Results of a principal component analysis and cluster analysis varied in life-history traits between the two geographic stocks and in elemental concentrations between the two seasonal cohorts. Squid in KL and PH might undertake different migration routes, while seasonal variability in oceanographic conditions was apparent in the two locations.

Among invertebrates, cephalopods have one of the most well-organized nervous systems. However, with respect to the ontogeny of the nervous system, the post-embryonic development of the cephalopod brain has only been documented for a few species. Here, we investigated the development of the brain of captive oval squid Sepioteuthis lessoniana during the post-hatching phase. The central part of the brain of the oval squid is divided into four main regions, namely, the supraoesophageal, anterior suboesophageal, middle suboesophageal, and posterior suboesophageal masses, each consisting of several lobes. At various ages in juvenile squid, the total volume of the central part of the brain (except the optic lobe) is significantly correlated with its body size, indicated by mantle length and wet body weight. The vertical lobe, superior frontal lobe, and anterior subesophageal mass drastically increase in relative volume as the squid grows. In contrast, the middle suboesophageal mass and posterior suboesophageal mass do not increase in volume with increasing squid age and body size. The effects of these results have been discussed in relation to the onset of squid behaviours during post-hatching.

The lessepsian species, Upeneus pori (Pisces), Sepioteuthis lessoniana (Cephalopoda) and Aquilonastra burtoni (Echinodermata) are reported for the first time from Cyprus, while the lessepsian bivalve, Barbatia plicata is reported for the first time from Kastelorizo Island, Greece. Finally, the fish species Pempheris vanicolensis, Sphyraena pinguis and Hemirampus far were collected more northerly than their previous records in the Aegean Sea. The geographical distribution of these species is given. According to the new records, the number of lessepsian fish, mollusc and echinoderm species known from Cyprus increases to 25, 38 and 4 species respectively.

Three consecutive generations of the oval squid, Sepioteuthis lessoniana, were cultured between October 2000 and May 2002 to investigate the life history of this species. Starting with the parental generation (wild-caught sub-adult squid from Tokushima Prefecture, Japan), we successfully obtained first and second generations. Life span and maturation of cultured oval squid and wild oval squid caught from the same habitat during April 2001 through to March 2002 were compared. Captive squid matured earlier and had a shorter life span (189–247 days) than the wild-caught squid (approximately one year) but reached an equivalent final body size. More ova were found in the oviducts of cultured females than in the oviducts of wild-caught females. Ultimately, collapse of the culture population was mainly due to the low rate of embryonic development of spawned ova, which might have resulted from the abnormal arrangement of ova in egg cases produced by later generations of females.

Oval squid Sepioteuthis lessoniana hatchlings originated from maternally identical egg strings were incubated under constant temperature and examined with special reference to statolith formation. Statoliths of a hatchling already had an adult-like shape, and some increments were observed. In spite of the maternally identical origin and constant incubation temperature (25°C), dorsal mantle length and statolith length of the hatchlings varied from 4.70 to 6.26 mm and 320 to 410 μm, respectively (N=14). These variations had a positive correlation with the embryonic duration ranging from 22 to 27 d, which means that the size of body and statolith becomes larger in hatchlings hatching later.

This article reports on four different juvenile reef fish species, Polydactylus virginicus, Haemulon aurolineatum, H. steindachneri and Carangoides bartholomaei swimming along with schools of the caribbean reef squid Sepioteuthis sepioidea. Three different behaviours were observed. This is the first record of this squid species on Brazilian reef habitats. We suggest that this behaviour is mainly related to protection for juvenile fish against potential pelagic predators.

INTRODUCTIONWild-caught squids have seldom survived for very long in laboratory aquaria. Tardent (1962) maintained Loligo vulgaris Lamarck, 1789 for a maximum of 60 days. Choe & Oshima (1963), Choe (1966) and LaRoe (1971) reared squids of the genus Sepioteuthis from eggs to adult size. Between 1975 and 1982 several successful attempts to maintain Loliginidae (e.g. Matsumoto, 1976; Hanlon, Hixon & Hulet, 1978, 1983; Yang et al. 1980, 1983) and Ommastrephidae (Flores et al. 1976; Flores, Igarashi & Mikami, 1977; O'Dor, Durward & Balch, 1977) were made. But to date only ten squid species have been maintained for more than forty days (review: Yang et al. 1980; Boletzky & Hanlon, 1983). Loligo opalescens Berry, 1911 holds the record for longevity in captivity at 233 days from egg to adult (Yang et al., 1983).