The completed life cycle of the octopus

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  1. mucktopus

    mucktopus Haliphron Atlanticus Staff Member Moderator

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    from Iglesias J., Otero J.J., Moxica C., Fuentes L. & Sanchez F.J. (2004) The completed life cycle of the octopus (Octopus vulgaris, Cuvier) under culture conditions: paralarval rearing using Artemia and zoeae, and first data on juvenile growth up to 8 months of age. Aquaculture International, 12, 481-487:

    Abstract. This paper shows innovating results on Octopus vulgaris Cuvier 1797 growth under
    culture conditions during the whole life cycle. Experiments were conducted at the Spanish
    Institute of Oceanography of Vigo (Spain). Using mean water temperature of 22.5◦C (ddw: 72.5 F), salinity of 35 (ddw: 1.026 SG) and adult Artemia (1–4mm of total length) along with a diet complement of Maja squinado zoeae as living prey, it was possible to obtain a 31.5% paralarval survival at day
    40 after hatching. At this age, paralarvae had reached a dry weight of 9.5mg, 23 suckers per
    arm, and they began the settlement process. First results on juvenile growth showed that they
    reached 0.5–0.6 kg at the age of 6 months after hatching, and 2 months later, they attained
    weights ranging between 1.4 and 1.8 kg. Mean temperature of the ongrowing process was
    18◦C.

    Material and methods
    Two thousand recently hatched (day 0) paralarvae were obtained from spontaneous
    spawning of female octopuses kept in captivity using the technology
    described by Moxica et al. (2001). They were transferred to a 1m3 PVC
    tank provided with filtered seawater (1 μm) at a concentration of 2 ind l−1.
    Tank was circular (130 cm of diameter) with black wall and white bottom.
    Mean water temperature was 22.5◦C (19.6–22.9), salinity 35 (34.2–35.7)
    and a 24 h light cycle was provided with two 36Wdaylight fluorescent tubes,
    resulting in an intensity of 600–1000 lux on surface. Levels of dissolved oxygen,
    nitrites and ammonium were measured daily. A close water circuit with
    central aeration was maintained during the first week. Microalgae (Chlorella
    sp., Isochrysis galbana and Chaetoceros sp.) were added daily in order to feed
    the remaining preys in the culture tank, to keep them in the best nutritional
    condition. From day 8 on, the water system was partially open (10 lmin−1) 4h
    per day, with a central outlet provided with a 300 μm filter. The tank bottom
    was cleaned by siphoning every 4 days.
    Live diet consisted of adult Artemia (1–4mm TL) cultivated at 25◦C during
    a week with a commercial cereal mix, Blevit Plus (from Ordesa Co.)
    and enriched for 24 h with Chlorella sp. Artemia concentration was of 0.05–
    0.1 indml−1. As a complementary diet, spider crab (Maja squinado Herbst
    1788) zoeae, obtained from 16 ovigerous females, were added 4 days per
    week at a concentration of 0.01–0.1 indml−1.
    Dry weights of 10 paralarvae were recorded fortnightly after being washed
    with distilled water, dried at 55◦C for 24 h and weighed individually. Survival
    483
    was recorded by counting the final number of survivors at day 40, and the
    mean number of suckers per arm was also registered from 10 individuals at
    this age.
    In order to start the weaning process, two groups of 250 individuals (40
    days-old) were transferred to 500 l square (1×1×0.5m3) grey tanks provided
    with sand, gravel and macroalgae. An open water system of 2 lmin−1 was
    used, with a surface inlet and a bottom central outlet of 1mm mesh size. The
    rest of animals (n=130) were kept in the former larval tank. Mean temperature
    during the weaning period was 22.5◦C. Diet consisted of sea urchin
    (Paracentrotus lividus) and common crab (Carcinus maenas) gonads, live
    small crustaceans (amphipods, mysidacea and shrimps) and thawed mussels
    (Mitylus sp.). After the weaning period (2 weeks), subadults were fed with
    frozen crabs and mussels; tank temperature was gradually decreased until
    ambient values (17–19◦C). The same grey tanks were used in the ongrowing
    period. Wet weight was recorded monthly throughout an 8-month period, in
    order to obtain the first data on octopus cultivated from the paralarvae stage
    up to final weights of 1.4–1.8 kg.

    AND:
    First feeding of Octopus vulgaris Cuvier, 1797 paralarvae using
    Artemia: Effect of prey size, prey density and feeding frequency
    J. Iglesias ⁎, L. Fuentes, J. Sánchez, J.J. Otero, C. Moxica, M.J. Lago:

    Abstract
    Different assays related to the first feeding of Octopus vulgaris Cuvier, 1797 are compiled in this paper. They include: age at
    initial feeding age, prey size selection and optimal density, attack timing after feeding, and effect of dose number on the number of
    captures. Prey capture and ingestion processes were also analysed. Food supplied was cultured Artemia sp. Each assay lasted
    15 min.
    Although paralarvae already start to feed on the hatching day (day 0), it is during day 2 when a greater number of attacks is recorded
    (81.7±14.7% paralarvae attack). They mainly prefer (significance level α=0.05) large Artemia, 1.4±0.4 mm (77.0±5.6% of the total
    attacks) than small Artemia, 0.8±0.1 mm (23.0±5.6%). There is also a slight predilection for the lowest Artemia concentration (33.3±
    12.6% paralarvae attack in a 0.1 Artemia ml−1 density, opposite 16.7±7.6 and 18.3±7.6% in densities of 0.5 and 1 Artemia ml−1
    respectively). The greatest predatory activity is recorded during the first 5 min after food is supplied (72.2±25.5%). An increase in the
    predatory activity was also observed when food was distributed in several doses instead of a single dose (75.0±10.0%and 46.7±17.6%
    respectively). It was proved for the first time that paralarvae completely ingest their preys (including their exoskeletons), in this case
    Artemia. Time needed for their total ingestion ranges between 4 and 10 min.
    © 2006 Elsevier B.V. All rights reserved.


    VIA EMAIL: LET ME KNOW if you can't get a hold of this second paper, which has more detailed methods.
     

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