First Description of the Eggs and Paralarvae of the Tropical Octopus, Octopus Insularis, Under Culture Conditions Author(S): Tiago M

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

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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, the eggs, egg masses, fecundity, and newly hatched Breeding was conducted in three tanks. With one male paralarvae of O. insularis. and three females as breeding stock, it was necessary to rotate the male among the three tanks to ensure that mating occurred with all the females. The male was observed to copulate with all MATERIALS AND METHODS the females soon after it was placed in the same tank. During copulation the male inserted the hectocotized Broodstock collection and maintenance arm (3rd right arm) inside the mantle cavity of the female and Broodstock (three females and one male) were captured copulation was observed to last around 20–30 min. There by scuba diving at a depth of 7–9 m along the coast of Rio were no fi ghts between the octopuses, as there was plenty of Grande do Norte State (5°16′S, 35°18′W) on 25 October 2011 food and shelter, but the octopuses were always positioned in and maintained for four days at the Technological Center of front of their dens as if they were protecting their shelters. Aquaculture, at the University of Rio Grande do Norte. After Twenty-six days after arrival at the laboratory, spawning this previous acclimation, the octopuses were air-freighted in was confi rmed, when the fi rst clusters of eggs were observed their original seawater to the Laboratory of Cephalopod on November 21, 2011. On November 28, another female Culture and Experimental Marine Ecology (LaCCef) at the spawned and eggs were seen in another tank. Spawning lasted University of Paraná in southern Brazil. The transportation for several days. time was approximately 10 h. Upon arrival, the octopuses Fecundity was estimated by counting the total number of were weighed individually (male: 1340 g; females: 1630 g, eggs in three clusters of strings of one female (the mean num- 1680 g, and 1810 g) and acclimatized to a closed recirculation ber of strings per cluster and mean number of eggs per cm of water system at 26 ± 1 °C and 32 ± 1 salinity. The recircula- string was obtained; the length of all strings was measured to tion system consisted of three culture tanks, two rectangular estimate the total number of eggs spawned per female). tanks (1.6 m length x 0.4 m height x 0.3 m width, 192 L; 0.69 m Embryonic development was monitored throughout length x 0.5 m height x 0.3 m width, 106 L) and one circular development. One day after spawning and one day prior to tank (superior edge diameter of 1.22 m, inferior opening the fi rst hatching day, samples of 30 eggs each were obtained diameter of 0.96 m, height of 0.58 m, 300 L utilized), all for image acquisition using a compound microscope attached connected to a biofilter (1.8 m length x 0.6 m height x to a high-resolution, computer-based video system. The eggs 0.3 m width, 325 L). The system was connected to a 13 W were collected and immediately photographed in a large Petri DESCRIPTION OF EGGS AND PARALARVAE OF OCTOPUS INSULARIS 3 dish to ensure that they retained their natural characteristics. taken in the dorsal view (mantle, head, and arms), ventral Measurements were obtained using public domain NIH- view (mantle, funnel, head, and arms), and lateral view (head, Image software. The eggs length and diameter were obtained eyes, arms, and funnel) and followed anterior to posterior by image analysis. The wet and dry weights of 10 samples of orientation of the paralarvae body (Hochberg et al. 1992). 15 eggs each on the fi rst day after spawning were also obtained For example, for funnel, the pattern 4+2+2 represents 4 chro- according to Vidal et al. (2002). The developmental stages matophores near the funnel aperture, 2 chromatophores in were based on the scale proposed by Naef (1928). the median region, and 2 more chromatophores in the posterior region (funnel base). Description of morphology and chromatophore pattern of paralarvae A total of 19 newly hatched live paralarvae were randomly RESULTS sampled from the rearing tanks and placed on petri dishes for capture of dorsal, ventral, and side views digital images with the Broodstock behavior and spawning same procedure used for the eggs. The morphological descrip- Four days before laying eggs, the females stopped eating. tion was based on the measurements of the following body The male fed normally during this period and was removed dimensions: total length (TL), mantle length (ML), mantle width from tanks holding the brooding females. The egg strings (MW), length of the second pair of arms (A2L), head width were attached to the posterior upper wall of the PVC shelter, (HW), funnel length (FL) eye diameter (ED), and number of and the females remained in their dens cleaning, ventilating, suckers on the arms (Fig. 1) according to Roper and Voss (1983). and caring for the egg, dying from a few days to a week after After image capture, the paralarvae were fi xed in 70% all the paralarvae have hatched. alcohol. Schematic drawings of the paralarvae were produced to describe the chromatophore pattern. A description of the Egg laying, fecundity, and embryonic development chromatophore pattern was performed based on the images The spawning process lasted approximately seven days. Fecundity was estimated at 85,000 eggs per female and was most likely 30% underestimated, as a few egg strings were lost in the fi rst days after spawning. The mean 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 2.29 ± 0.06 mm and 0.92 ± 0.03 mm, respectively, one day before hatching. Also, the mean wet and dry weights of the eggs on the fi rst day after spawning were 0.70 ± 0.17 mg and 0.33 ± 0.03 mg, respectively. The eggs had a prolate ellipsoid- shaped chorion, which was devoid of other capsules, and a short chorion stalk that was enlarged at the free end (Fig. 2a). Egg strings of variable size were attached to the den wall by female. The female attached the egg strings to a central axis (Fig. 2b), forming strings of a variable number of eggs. In a complete clutch, 108 strings were counted, and the presence of 790 eggs was estimated per string (Table 1). Embryonic development lasted for 30–38 days. Figure 1. Schematic illustration showing the body dimensions measured in Octopus insularis Based on the embryonic develop- paralarvae. Abbreviations: a2l, length of the second pair of arms; ed, eye diameter; fl , funnel length; hw, head width; ml, mantle length; mw, mantle width; tl, total length. ment stages defi ned by Naef (1928), cell division occurred shortly after 4 AMERICAN MALACOLOGICAL BULLETIN 33 · 1 · 2015

Table 1. Octopus insularis. Numerical, morphometric and weight pigmented showing a brownish retina (stage XVI and characteristics of eggs and egg strings from a 1680 g female. Mean XVII). weights are based on 10 samples of 15 eggs each. The advanced developmental stages (stage XIX) before (Fig. 3b) and after (Fig. 3c) the second inversion of the Mean ± SD Range N embryo occurred on day 30-31, indicating the end of organ- Number of eggs per strings 790.6 ± 163.9 647–1085 15 ogenesis. The eyes exhibited a darkish-brown retina and a Length for strings (mm) 75.8 ± 15.7 48–104 15 conspicuous lens, the ink sac was fully formed, and the Eggs width (mm) 0.91 ± 0.03 0.8–0.97 130 mantle and funnel were well developed. No signifi cant mor- Eggs length (mm) 2.25 ± 0.09 2.06–2.47 130 phological modifi cations were observed from day 31 to day Wet weight (mg) 0.70 ± 0.17 0.46–0.90 10 38, with exception of the outer yolk sac that was substan- Dry weight (mg) 0.33 ± 0.03 0.30–0.40 10 tially reduced, accompanied by an increase in the volume of the inner yolk sac. fecundation; however, the blastodisc was only clearly visible beginning on the day 7 (stages I–III), resulting in an increase Description of paralarvae and their chromatophore in cell number (morula). The blastoderm spread by mar- pattern ginal cell division over the uncleaved yolk mass at this stage, The mean TL and ML of newly-hatched paralarvae was covering 10–20% of the embryo length between days 7 and 2.34 ± 0.16 mm and 1.68 ± 0.13 mm, respectively. The funnel 10 (stages IV and V). The organogenesis followed, which is (0.49 ± 0.05 mm) was well developed, occupying almost characterized by the production of organs formed during the entire length of the head in the ventral region. The arms gastrulation. Prior to early organogenesis, the fi rst inversion were short with three well defi ned suckers of approximately of the embryo was observed on day 19; however, not all the same diameter. The eyes had a mean diameter of 0.31 ± embryos went through the fi rst inversion (Fig. 3a). Advanced 0.04 mm, with the right and left always identical (Table 2). organogenesis was observed on day 22 corresponded to A skin membrane densely surrounded by Kölliker organs Stages XIII and XIV and a mean ML of 0.57 ± 0.013 mm covered the arms, head, and mantle, although it was more (n = 30). Also, eight buds, corresponding to the eight arms, prominent on the surface of the mantle (Fig. 3d). When vari- with suckers rudiments of were observed on the embryo. ability was observed among individuals, the most frequent The eyes pigmented (orange) and the mantle initially devel- number and pattern of chromatophores was listed. The chro- oped to partially cover the gills of the embryo. matophore pattern of paralarvae was described considering On day 25, the arms were more developed, showing the the dorsal, ventral and lateral views as follows. three suckers fully formed. Functional chromatophores were Dorsal view: Mantle: Three to 4 tegumental chromato- distributed on the mantle, ventral arms, head, and funnel. phores are distributed at the mantle edge and another four in The mean ML was larger (0.87 ± 0.26 mm, n = 25) and the the posterior region (Fig. 4a). The number of extrategumental eyes were also larger and more heavily pigmented, but still chromatophores on the central mantle covering the visceral reddish in color (stage XV). mass was between 6 and 11. These chromatophores exhibited An increase in the mean ML (1.22 ± 0.13 mm, n = 30), an oval shape but were arranged as one in the middle and the funnel, and arms in relation to the total size of the embryo other 8 distributed around this central chromatophore. Head: was observed on day 29. The eyes were larger and more A dense arrangement of 8 tegumental chromatophores was present: 2 between the eyes, 4 in corresponding middle position and 2 other at the central posterior region near the edge of the mantle. The lateral sides bore 1pair of extrategumental chromatophore. Eyes: 1chromatophore over the anterior portion of each eye (Fig. 4a). Ventral view: Mantle: Densely covered with tegumental chromatophores; an average of 40 chromatophores (Fig. 4b; Table 3) were distributed into 9 rows. The fi rst 3rows were arranged horizontally, while the next 6 rows Figure 2. Octopus insularis. A, Egg and B, Egg strings on the fi rst days after spawning. were distributed in a spiral form. Head: two extra-large extrategumental DESCRIPTION OF EGGS AND PARALARVAE OF OCTOPUS INSULARIS 5

The chromatophore pattern of Octopus insularis is very distinctive, with a total of ~90–111 chromatophores. In the dorsal view, from 17 to 25 chromatophores were found on the mantle (8–11 under the viscera), 9–12 on the head, and 3–4 in a single row on the arms. In the ventral view, 42–50 chromatophores were found on the mantle, 2–3 large chromatophores on the head, 4–5 on the arms, 8 on the funnel, and 2–4 around the eyes.

DISCUSSION

Octopus insularis produces small eggs and planktonic paralarvae in accordance to our hypothesis. The estimated number of 85,000 eggs for a 1680 g female, is comparable to the data Figure 3. Octopus insularis. Embryos at different developmental stages and paralarvae. A, Ini- found by Lima et al. (2014) who tial developmental stage before (down) and after (upper) the fi rst inversion of the embryo; reported that the number of oocytes in B, Advanced developmental stage before the second inversion of the embryo; C, Advanced O. insularis ovaries ranged between developmental stage after the second inversion of the embryo; D, Newly-hatched paralarvae with visible Kölliker organs on the surface of the mantle. 68,502–120,166, with average of 93,820. This number is much lower than the fecundity estimated for O. vulgaris, at chromatophores were always observed and when expanded, 100,000–500,000 eggs per female (Mangold 1983). However, occupied almost the entire surface of the head below the fecundity seems to be dependent on the weight and size of eyes; another tegumental chromatophore was present between females at the advanced maturity stage (Mangold 1983, Ré the eyes. Funnel: always contained 8 chromatophores dis- 1998, Boyle and Rodhouse 2005). Indeed, O. insularis is a tributed in a standardized manner, 4 of which were near the smaller species than O. vulgaris with a shorter life cycle at the orifi ce of the funnel (above), 2 in the middle, and 2 more at tropical environment; thus, it is expected that the fecundity toward the base of the funnel. Arms: a single row with 4–5 of O. insularis would be lower. Besides, although the latter has chromatophores. a gonadal development similar to O. vulgaris, it has relatively Side view: Next to the eyes 2–4 chromatophores were smaller gonads, lower absolute and relative fecundity, and always observed; 4 on the funnel and in the mantle, 4 extrat- year around production and release of spermatophores (Lima egumental on the viscera and several tegumental distributed et al. 2014). Furthermore, it was suggested by these authors on the mantle. that these reproductive characteristics of O. insularis are related to more predictable conditions at the tropical environment. Interestingly, this species has recently also been found at a subtropical estuary in southern Brazil (25°32′S, Table 2. Octopus insularis. Morphological measurements of hatchlings. 48°23′W) (EAG Vidal, unpublished data), where environmental conditions are quite variable. Thus, further studies are Mean ± SD (mm) Range (mm) N necessary to assess the fecundity of O. insularis of different Mantle length 1.68 ± 0.13 1.50–1.92 19 weights from different locations of its distributional range. Mantle width 0.98 ± 0.09 0.82–1.17 19 On the fi rst day after spawning the length and width of Length second pair of arms 0.66 ± 0.10 0.43–0.80 19 the eggs of Octopus insularis were 2.13 ± 0.06 mm and 0.82 ± Head width 0.86 ± 0.06 0.69–0.94 19 0.04 mm, respectively; thus, being slightly larger than the eggs Funnel length 0.49 ± 0.05 0.41–0.55 19 of O. vulgaris, which measure 1.8–2.0 mm in length and Eyes diameter 0.31 ± 0.04 0.25–0.36 18 1.0 mm in width (Nixon 1985, Boletzky and Fioroni 1990). Total length 2.34 ± 0.16 2.06–2.64 19 The slightly larger size of the eggs of O. insularis might 6 AMERICAN MALACOLOGICAL BULLETIN 33 · 1 · 2015

1961, Boletzky 1971), whereas the second inversion brings the advanced embryo into a position corresponding to that prior to the fi rst inversion by a unique dorsal folding movement, to provide ample space for the mantle after the second inversion prior to hatching (Boletzky and Fioroni 1990). Octopus insularis hatchlings are planktonic, a characteristics of octopus species with small oocytes and relatively high fecundity (Hochberg et al. 1992). However, O. insularis hatchlings are slightly smaller than those of O. vulgaris, whose hatchlings have a TL = ~ 3.0 mm and an ML= ~ 2.0 mm (Villanueva 1995, Nixon and Mangold 1996, Vidal et al. 2010). Both species display 3 suckers distributed a single row along the Figure 4. Octopus insularis. Schematic illustration of the chromatophore pattern of newly- arms, although the arms are shorter in hatched paralarvae. A, dorsal view; B, ventral view; C, lateral arrangement. O. insularis (~0.58 mm) than in O. vulgaris (~0.7 to 1.0 mm) (Villanueva 1995, indicate longer embryonic developmental time. The duration Vidal et al. 2010). Adult O. insularis shows shorter and thicker of the embryonic development in O. insularis was 30–38 days arms in comparison to O. vulgaris (Voight 1991), a difference at 26 ± 1 °C. However, the course of development was not that facilitates the discrimination of larger specimens of the identical, with different embryonic stages being observed two species (Leite et al. 2008). The hatchlings of O. insularis even in the same egg string. Caveriviere et al. (1999) found showed a similar pattern to adults, with the arms length com- that embryonic developmental time in O. vulgaris was 15–42 prising ~ 30% of the TL, in comparison with O. vulgaris which days at an average temperature of 27 °C and 29–49 days at consisted of ~ 45% of the TL (Vidal et al. 2010). approximately 22–23 °C. On previous experiments, with O. This study showed that the chromatophore pattern of vulgaris females of similar weight as the O. insularis female of Octopus insularis paralarvae is quite conspicuous. A compari- the present study, we have verifi ed an embryonic develop- son with the chromatophore pattern of O. vulgaris paralarvae mental time of 20–32 days at an average temperature of 26 °C described by Vidal et al. (2010), shows that the principal dif- (unpublished data). ferences between the two paralarvae occur in the dorsal man- Embryonic developmental times in cephalopods show tle and in the ventral view. The dorsal mantle of O. vulgaris an inverse relationship with temperature (Boletzky 1987), has 8–11 chromatophores, six of which are visceral, whereas thus higher temperatures will reduce the time to hatching. O. insularis shows an average of 17 chromatophores, with Temperature directly affects almost every aspect of the early 7–11 visceral. In ventral view, O. vulgaris shows an average of life history of marine larvae, including the hatching time, 23 chromatophores distributed in horizontal rows, whereas yolk utilization rate and effi ciency, and size and weight at fi rst O. insularis shows an average of 40 chromatophores divided feeding (Pechenik 1987, Boidron-Metarion 1995, Vidal et al. into 9 rows of which the fi rst three are arranged horizontally 2002). These physiological responses are due to the domi- and the others are distributed in a spiral form. On the funnel, neering effects of temperature on metabolism. However, the O. vulgaris exhibits four chromatophores with a 2+2 distribu- combined effects of temperature and salinity seem to be also tion; in contrast, O. insularis always shows eight chromato- important and deserve further investigation (Vidal and phores in standard 4+2+2 distribution. In total, O. vulgaris Boletzky 2014). shows 56–77 chromatophores, whereas O. insularis shows The embryonic stages observed in Octopus insularis closely 84–112. Interestingly, the color pattern of O. insularis adults resembled those of O. vulgaris described by Naef 1928. The fi rst is also much darker than that of O. vulgaris (Leite and Mather reversal of the embryo inside the chorion was observed at 2008), suggesting that the former species bears more chro- approximately stage VIII of Naef’s scale and the second inver- matophores than the latter. sion at stage XIX. The fi rst inversion is combined with a regular On the other hand, when compared to the other rotation around the axis of the egg case (Orelli and Mangold warm-water species, Octopus insularis still exhibits fewer DESCRIPTION OF EGGS AND PARALARVAE OF OCTOPUS INSULARIS 7

chromatophores than Amphioctopus burryi (Voss, 1950), for example, which displays approximately 205 chromatophores in total (Forsythe and Hanlon 1985). Similarly, O. maorum, native to New Zealand, shows approximately 220 (Batham 1957). Typically, older or brown chromatophores

Total Chromatophores are found in such regions as the mantle (ventral and dorsal), mainly covering the viscera, head (dorsal), arms, and funnel. Conversely, younger or reddish chromatophores are found on the head, whereas yellow chromatophores are generally small, appear in smaller quantities, and are 50–73 84–112 Total Ventral View observed only along the dorsal edge of the mantle. During the planktonic phase, the color changes are less pro- nounced, culminating with a small variety of chromatophores and a color pattern that is less complex when compared to newly settle benthic juveniles (Villanueva 1995, Vidal et al. 2010). Octopus insularis was recently described as a new species in northeastern Brazil (Leite et al. 2008) and discrimi- nated from the O. vulgaris complex. The present study provides fundamental information on the early life stages of O. insularis that will be essential to identifying paralarvae from plankton samples and achieving a better understanding of the ecology and distribution of the species. Accordingly, much of the information on the population Ventral Chromatophores 4–5 (1 row) 2+1 0–2 32–56 4+2+2 Arms Head Eyes Mantle Funnel dynamics of both species is confusing due to the difﬁ culties of discriminating them. Thus, more observations of the paralarvae, juveniles, and adults of O. insularis should be conducted in both natural and controlled environments. Octopus insularis should receive more focused attention, 30–43 Total Dorsal View particularly because it is the main target of ﬁ sheries in the northeastern Brazil and may have aquaculture potential due to its relatively high fecundity, easy adaptation to captivity Total of Mantle conditions at high temperatures, good acceptability of fro- zen food, and high market price.

ACKNOWLEDGMENTS

EAGV was funded by the Brazilian National Research Council (CNPq- no. 307204/2011-1 and 485653/2012-5). Edge of the Mantle Mantle

LITERATURE CITED Chromatophore number and pattern of hatchlings in different body areas. VS, Visceral; Y, Yellow.

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Submitted: 29 March 2014; accepted: 14 August 2014; ﬁ nal revisions received: 25 December 2014