First Description of the Eggs and Paralarvae of the Tropical Octopus, Octopus insularis, Under Culture Conditions Author(s): Tiago M. Lenz, Nathalia H. Elias, Tatiana S. Leite and Erica A. G. Vidal Source: American Malacological Bulletin, 33(1):1-9. Published By: American Malacological Society DOI: http://dx.doi.org/10.4003/006.033.0115 URL: http://www.bioone.org/doi/full/10.4003/006.033.0115 BioOne (www.bioone.org) is a nonprofit, online aggregation of core research in the biological, ecological, and environmental sciences. BioOne provides a sustainable online platform for over 170 journals and books published by nonprofit societies, associations, museums, institutions, and presses. Your use of this PDF, the BioOne Web site, and all posted and associated content indicates your acceptance of BioOne’s Terms of Use, available at www.bioone.org/page/terms_of_use. Usage of BioOne content is strictly limited to personal, educational, and non-commercial use. Commercial inquiries or rights and permissions requests should be directed to the individual publisher as copyright holder. BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research. American Malacological Bulletin Advanced Access published 27 February 2015 Amer. Malac. Bull. 33(1): 1–9 (2015) First description of the eggs and paralarvae of the tropical octopus, Octopus insularis, under culture conditions Tiago M. Lenz1, Nathalia H. Elias1, Tatiana S. Leite2, and Erica A. G. Vidal1* 1Centro de Estudos do Mar, Universidade Federal do Paraná. Pontal do Paraná, Paraná Brazil 2Dept. Oceanografia e Limnologia, Universidade Federal do Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil Correspondence, Erica Vidal: [email protected] Abstract: Octopus insularis (Leite and Haimovici, 2008) occurs in a wide region of the tropical Atlantic, inhabiting shallow waters along the coast and oceanic islands of northeastern Brazil, where it is considered the primary target of octopus fi sheries. This species was only recently described, and detailed information about its spawning, eggs, and paralarvae is unknown. The objective of this study was to estimate the fecundity, describe the eggs and paralarvae and the duration of embryonic development of O. insularis under culture conditions. Broodstock were captured and transported to the laboratory, where they were acclimated in a closed recirculation water system at 26 °C and 32 salinity. Eggs were obtained from two spawning females and were monitored throughout development; samples of 30 eggs were obtained 1 day after spawning and 1 day prior to the fi rst hatching day, and their length, diameter and weights measured. The duration of embryonic development lasted from 30–38 days and fecundity was estimated as 85,000 eggs per female. The length and width of the eggs on the fi rst day after spawning were 2.13 ± 0.06 mm and 0.82 ± 0.04 mm, respectively, and were 2.29 ± 0.06 mm and 0.92 ± 0.03 mm, respectively, one day before hatching. The newly hatched paralarvae exhibit 3 suckers per arm and a mean mantle length of 1.68 ± 0.13 mm. The chromatophore pattern of paralarvae is conspicuous, with ~ 90–111 chromatophores. A total of 32–40 and 56–69 chromatophores were found on the dorsal and ventral view, respectively. These results are of essential importance for identifying the eggs and paralarvae of O. insularis and in broadening our knowledge of this species. Key words: cephalopod, chromatophore, embryonic development, fecundity, Octopus Octopus insularis (Leite and Haimovici, 2008) is a medium- management of stocks (Boyle and Rodhouse 2005). Besides, sized octopus and is the principal commercial cephalopod spe- information on the morphology and distribution of early cies around the tropical oceanic islands of Brazil and along the stages of cephalopods is of crucial importance for discrimi- country’s northeastern coast. Octopus insularis shows distinct nating populations and identifying species (Young et al. 1989, morphological characteristics from its sympatric congener O. Hochberg et al. 1992, Vidal et al. 2010). vulgaris Cuvier, 1797, including short and stout arms, mantle, Benthic, littoral octopuses species produce a small num- and head with large reddish-brown rough skin (Leite et al. ber of eggs, e.g., Octopus joubini Robson, 1929 (< 100) (Hanlon 2008). A recent study also described distinct reproductive fea- 1983), whereas others may produce several hundred thousand tures, such as relatively smaller gonads, lower absolute and eggs, e.g., O. vulgaris (100,000–500,000) (Mangold 1983) and relative fecundity in the ovary, year round production and O. maorum Hutton, 1880 (> 50,000) (Grubert and Wadley release of spermatophores, and group-synchronous ovulation 2000). High fecundity species produce small eggs that hatch (Lima et al. 2014). This species occurs throughout the year in into planktonic paralarvae. Lower fecundity species produce shallow waters, where it is the focus of artisanal fi sheries (Lima relatively few large eggs, resulting in more highly developed et al. 2013), and is usually found in rocky and reef habitats, benthic hatchlings that resemble the adult (Villanueva and where it feeds primarily on crustaceans, bivalves, and gastro- Norman 2008). Ré (1998) has suggested that fecundity depends pods and, less frequently, on cephalopods and fi sh (Leite, on the weight of females, and Osborn (1995) has stated that, on Haimovici and Mather 2009, Bouth et al. 2011). an absolute basis, larger females laid more festoons containing Several studies have sought to understand aspects of the a greater density of eggs. This author also suggested that the biology and ecology of Octopus insularis by focusing primarily maintenance of females under optimal laboratory conditions on adults and juveniles (Leite, Haimovici and Mather 2009, Leite may increase the amount of energy available for egg produc- Haimovici and Mather et al. 2009, Bouth et al. 2011, Lima et al. tion and may ultimately increase fecundity. 2013). However, as it was not previously distinguished from O. Embryonic development in cephalopods is inversely vulgaris complex, only recently described as a new species, there related to water temperature (Mangold and Boletzky 1973, is virtually no information on the early life stages of O. insularis. Boletzky 1974). In fact, temperature is known to affect all Knowledge on early life stages is required for a better metabolic processes, such as respiration, excretion, yolk utili- understanding of life cycles, ecology, and the sustainable zation, and consequently, developmental time and size of 1 2 AMERICAN MALACOLOGICAL BULLETIN 33 · 1 · 2015 newly-hatched paralarvae (Bouchaud 1991, Caverivièrie et al. ultra-violet fi lter, and two PVC shelters (30 cm length x 10 cm 1999, Vidal et al. 2002). diameter) were offered per animal. Octopus paralarvae are delicate, have short arms with few The broodstock diet consisted of live prey: blue crab suckers and limited swimming ability (Villanueva and (Callinectes sapidus, Rathbun 1869), oyster (Crassostrea Sacco, Norman 2008). Paralarvae have primarily been described 1897 sp.), and mussels (Perna perna Linnaeus, 1758). The shells based on their chromatophore pattern, as the number and and tissues not ingested were rapidly removed from the tanks distribution of chromatophores on the skin are species-specifi c. to ensure the maintenance of water quality. Broodstock were Indeed, the chromatophore pattern is conservative and can initially fed live crabs only at night. After capturing the food, be used as a reliable taxonomic characteristic to identify the octopuses brought it into the shelters and then discarded paralarval cephalopods (Young et al. 1989, Hochberg et al. only the remains. After 4 days, the octopuses became accus- 1992). tomed to feeding by handlers during the day and were able to There is no available information on the embryonic capture defrosted fi sh. The sardine, Sardinella brasiliensis and post-embryonic development of Octopus insularis. Further- (Steindachner, 1879) was provided as food to the octopuses at more, maintenance under laboratory conditions has not pre- a ratio of one sardine per octopus per day; live crabs were viously been accomplished but can potentially provide rich offered at a ratio of one to two crabs per octopus per day. information on embryonic development and morphological Every day, the tanks were cleaned and siphoned to remove par- features of eggs and hatchlings (Vidal et al. 2014). This ticulate matter, food waste, and the excreta of the animals. knowledge may help to examine such important features Partial exchanges of water (20% daily) were performed to as reproductive behavior in captivity, number of eggs laid, reduce the nitrate levels and replenish the water removed by egg characteristics, and embryonic developmental times. cleaning. Measurements of physical and chemical parameters Due to the morphological similarity between Octopus (salinity, temperature, pH, and nitrogen compounds- nitrite, insularis and O. vulgaris, we aim to investigate the hypothesis nitrate, and ammonia) were performed daily. that these species have a similar mode of development; pro- ducing a large number of eggs and planktonic paralarvae. Copulation, breeding, egg laying, fecundity, and Therefore, the objectives of this study are to describe, for the embryonic development fi rst time,