Laboratory observations on spawning and embryonic development of a blue-ringed octopus

A female blue-ringed octopus, Hapalochlaena sp. (probably lunulata), was maintained in an aqarium for nearly 3 months, during which time it spawned and cared for the eggs until hatching. The young are planktonic. Embryonic development does not differ markedly from that observed in other octopods, uniting certain features of the development of Octopus vulgaris and Eledone cirrosa. In terms of reproductive biology and development, the species differs from the lesser blue-ringed octopus Hapalochlaena maculosa in its mode of spawning, egg size and mode of life of its young. These differences correspond to conditions recorded for Octopus spp. and Eledone spp

Congenital malformation of the systemic heart of Sepia officinalis l.: morphological, phylogenetic and ecotoxicological aspects

Numerous preparations of the circulatory system of Sepia officinalis L. caught from the Bay of Arcachon (Atlantic Coast of France) in 1989 and 1996 showed an obvious congenital malformation of the systemic heart complex. The malformation consisted of a cord- or truncus-like structure at the left cranio-apical ventricle. It is interpreted as an atypical second root of the cephalic aorta reflecting an originally paired anlage of the heart in ancestral cephalopods. In considering possible causes of this atavistic abnormality, the high tributyltin (TBT) contamination recorded in the Bay at the time should not be overlooked

Laboratory rearing of Sepiolinae (Mollusca: cephalopoda)

Five species of Sepiola were reared in the laboratory from egg to adult size. Spawning was achieved in 3 species of Sepiola afteer 5 to 7 months. The growth rate of the species reared did not depend upon temperature, which ranged from 12,5° to 20°C. A fairly constant size increase (2,5mm mantle length/month) was observed in Sepiola during the 5 months after hatching. In Sepietta, the same growth rate was observed until the fourth month after hatching, when it increased to the rate of 5 mm mantle length/month

New data on reproductive biology and growth of Octopus vulgaris

The problems of reproduction of Octopus vulgaris and the seasonal distribution in the sea of planctonic larvae, benthonic juveniles and adults are discussed. The influence of environmental factors on growth is shown by experimental studies in the laboratory, and the difficulties of interpreting field data are emphazised

Reproductive biology and embryonic development of Eledone cirrosa (Cephalopoda: Octopoda)

Analyses of bottom trawl samples and feeding experiments in the laboratory revealed a reproduction period ranging from late March to early August in Eledone cirrosa of the Catalonian Sea (Western Mediterranean). The embryonic development, studied for the first time on eggs laid in the laboratory, shows no basic difference from that of other Octopodiae. The newly hatched animals are planctonic; Morphologically, this feature is expressed by a relatively small arm-length

Field and laboratory behavior of "macrotritopus larvae" reared to Octopus defilippi Verany, 1851 (Mollusca: Cephalopoda)

Seventeen advanced macrotritopus “larvae” from 7 to 15 mm mantle length were attracted to underwater lights in St. Croix, U.S. Virgin Islands. Their behavior was observed in situ, then seven were captured alive and one female was reared to an adult Octopus defilippi. The characteristic long arms of the planktonic young appear to function in flotation, feeding, crawling and defense. There is evidence that larger macrotritopus may be planktonic by night and benthic by day; thus the transition from a planktonic to benthic life may be controlled to ensure widespread distribution on to a suitable habitat. Morphological examination of 106 specimens from the Atlantic indicate that all macrotritopus “larvae” from this ocean are O. defilippi

A comparison of the light organ development of Sepiola robusta Naef and Euprymna scolopes Berry (Cephalopoda: Sepiolidae)

Light organ development was studied in the sepiolid squid Sepiola robusta Naef and compared to that of Euprymna scolopes Berry. Both species form obligate mutualisms with luminous bacteria from the environment. The embryonic period of S. robusta, which is at least double to that of E. scolopes at similar temperatures, produced additional features not reported to occur in the E. scolopes light organ, including an extended ciliated ridge at the base of the light organ, as well as additional crypt spaces to house symbiotic bacteria. Accessory structures, which are used to modify the bacteria-produced light, are not under the induction of symbiotic bacteria and appear in S. robusta before hatching, whereas in E. scolopes these tissues form post-hatching. At hatching the light organs of both species respond to symbiotically competent bacteria and undergo similar developmental remodeling. Specifically, the ciliated epithelial fields on the surface of the light organ undergo a program of cell death and regression that spans 4 to 5 d in E. scolopes, and over 9 d in S. robusta. Although the timing of embryogenesis differs between these two species, the results of these studies demonstrate that the influence of Vibrio fischeri, the specific symbiont, appears to be restricted to the initial stages of post-hatching development of both light organs