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"Octopuses Life cycles."
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The bizarre life cycle of an octopus
Readers learn about the unique life cycle of the octopus, including facts such as a mother octopus doesnt eat while taking care of her eggs and neither male nor female octopuses live very long after becoming parents.
Book
Early Mode of Life and Hatchling Size in Cephalopod Molluscs: Influence on the Species Distributional Ranges
Cephalopods (nautiluses, cuttlefishes, squids and octopuses) exhibit direct development and display two major developmental modes: planktonic and benthic. Planktonic hatchlings are small and go through some degree of morphological changes during the planktonic phase, which can last from days to months, with ocean currents enhancing their dispersal capacity. Benthic hatchlings are usually large, miniature-like adults and have comparatively reduced dispersal potential. We examined the relationship between early developmental mode, hatchling size and species latitudinal distribution range of 110 species hatched in the laboratory, which represent 13% of the total number of live cephalopod species described to date. Results showed that species with planktonic hatchlings reach broader distributional ranges in comparison with species with benthic hatchlings. In addition, squids and octopods follow an inverse relationship between hatchling size and species latitudinal distribution. In both groups, species with smaller hatchlings have broader latitudinal distribution ranges. Thus, squid and octopod species with larger hatchlings have latitudinal distributions of comparatively minor extension. This pattern also emerges when all species are grouped by genus (n = 41), but was not detected for cuttlefishes, a group composed mainly of species with large and benthic hatchlings. However, when hatchling size was compared to adult size, it was observed that the smaller the hatchlings, the broader the latitudinal distributional range of the species for cuttlefishes, squids and octopuses. This was also valid for all cephalopod species with benthic hatchlings pooled together. Hatchling size and associated developmental mode and dispersal potential seem to be main influential factors in determining the distributional range of cephalopods.
Journal Article
The den that octopus built
\"The solitary and ingenious octopus is a master of disguise and invention, creating her den out of the objects of the ocean, from shells and rocks to tiny glass shards. Using creative methods of hunting and construction, the octopus prepares for the biggest task of her life: motherhood. With one last, poignant gesture of love, the mother octopus sends her hatchlings on their way, starting a new cycle for the baby octopuses\"-- Provided by publisher.
Book
The settlement stage in the common octopus Octopus vulgaris Cuvier, 1797: a complex transition between planktonic and benthic lifestyles
Merobenthic octopods like Octopus vulgaris undergo a transitional period between the planktonic and benthic phases, known as settlement stage. In this work, three sub-stages (“pre-settlement”, “settlement” and “post-settlement”) have been defined based on morphological, anatomical, and behavioural changes. At the end of the planktonic phase advanced paralarvae are transparent with 65–80 chromatophores, iridophores covering eyes and digestive system, Kölliker organs, circular pupils, ~ 20 suckers per arm (spa), and mantle length (ML) bigger than total length (TL; ML/TL > 60%). The “pre-settlement” sub-stage (ML/TL from 65 to 55%, ~ 20–25 spa) is marked by the onset of clinging reflexes, where the pre-settlers touch the walls and bottom of the tank and start crawling clumsily. Morphologically, they are transparent with increased chromatophores along the arms and iridophores around the eyes and head. During the “settlement” sub-stage (~ 55–48% ML/TL, ~ 25–35 spa) there is an exponential increase of chromatophores in the dorsal area of head and mantle, and the settlers show strong negative phototaxis, crawling for shelter when disturbed. The skin is still transparent but new chromatic cells (leucophores) develop and Kölliker organs are almost lost. During the “post-settlement” sub-stage (~ 48–40% ML/TL, > 35 spa) the post-settlers display very fast and coordinated movements, have horizontal pupils, and develop the “eye-bar”. The chromatic cells keep increasing exponentially, giving a pale appearance to the skin. The beginning of the benthic phase in O. vulgaris juveniles is marked by the presence of skin sculptural components (papillae) and a complex display of chromatic, postural, and cryptic patterns.
Journal Article
Environmental assessment of common octopus (Octopus vulgaris) from a small-scale fishery in Algarve (Portugal)
Abstract PurposeCommon octopus is the fishing species with highest economic revenue in Portugal, and its consumption per capita is very high. The majority of catches come from the small-scale fleet with pots and traps. The aims were to assess main environmental impacts of common octopus’ fishery with traps and pots in the Algarve region, where the most important fleet size and landings volume occurs, and to find if there are significant differences between both fishing gears.MethodsThe assessment includes standard LCA impact categories, fishery-specific impact categories, and quantification of macroplastics and microplastics emitted to the environment. The functional unit selected was 1 kg of octopus and the study was a ‘cradle to gate’ system. The scope included fishing operations until the product is landed at the harbour. Primary data was obtained by face-to-face questionnaires from 22 vessels, with an average of 1005 pots and 1211 traps per vessel, and 372 pots and 234 traps lost annually to the environment. Plastic pots have a concrete block and traps are a metal framed covered by plastic netting. Each trap or pot is connected to the main line at regular intervals. Unlike traps, pots do not need bait.Results and discussionFuel contribution to global warming is very high and where the highest potential exists to lower down the carbon footprint. The fuel use intensity resulted in 0.9 L/kg of octopus. The bait used in traps is significant and raises further environmental costs related with fuel consumption. The use of traps represents more than two times the impacts found for pots in all the categories studied except ecotoxicity categories. Zinc use was the main contributor to ecotoxicity categories, but it has not been included in other fishery LCA studies. It was estimated that 12.2 g of plastics is lost to the environment per kg of octopus. The loss of macroplastics from fishing gears was the highest contributor.ConclusionsThe carbon footprint obtained was 3.1 kg CO2 eq per kg of octopus, being lower compared to other seafood products, and less than half compared to octopus caught with trawling. Pots and traps are highly selective fishing gears, causing negligible disturbance to the seafloor. The stock is not assessed, but management measures exist and can be improved. A drawback exists related with gears lost to the environment.
Journal Article
The trophic interactions of Octopus insularis in the food web of a pristine tropical atoll: a baseline for management and monitoring under environmental changes
In the present study, we evaluated the trophic role of Octopus insularis Leite and Haimovici 2008 in the food web of Rocas Atoll, a preserved insular territory in the Southwest Atlantic. Using stable isotope analysis of C and N, we showed that the local trophic web comprises at least four trophic levels, where the octopus occupies a trophic position (TP) between the second and third trophic levels (mean ± SD TPadditive = 3.08 ± 0.36; TPBayesian = 3.12 ± 0.17). Among other benthic/reef-associated consumers, this cephalopod stood out for its much wider isotopic niche, pointing to a diet diversified in carbon sources, but focussed on prey in lower TPs. This finding was in accordance with the time-minimizing feeding strategy described for the species, which seemed almost permanent throughout the life cycle of the octopus, given the great niche overlap between octopuses in different maturity stages and their very similar trophic positions. Also, as a prey, octopuses composed up to almost 23% of the diet of some benthic/demersal predators. Overall, O. insularis represented an important mesopredator for the local food web, principally for bottom-associated organisms, while also serving as a substantial energy input to the next trophic levels.
Journal Article
Demographic inference and genetic diversity of Octopus mimus (Cephalopoda: Octopodidae) throughout the Humboldt Current System
Climatic and oceanographic events occurring during the last glacial cycle in the Humboldt Current System (HCS) have left genetic footprints in marine invertebrate populations. The objective of this study was to evaluate the effect of the glacial period on Octopus mimus populations found throughout the HCS. This species lays a large number of small eggs which hatch into planktonic paralarvae with the potential to undergo wide dispersal. We sequenced the COIII gene to perform phylogeographic analyses of 197 octopuses sampled from seven localities. The genetic diversity of Octopus mimus was low and decreased towards the southern end of the distribution range, which comprises a single population. The haplotype genealogy and Bayesian Skyride plot suggest that O. mimus underwent a demographic expansion after the last glacial maximum (LGM). This would imply a contraction of the range of this organism toward northern latitudes during the LGM followed by southward expansion and recolonization once the contemporary interglacial period began.
Journal Article
Morphogenesis and Organogenesis to Hatching of the Green Octopus, Octopus hubbsorum: A Species That Includes a Paralarval Stage in Its Life Cycle
This work describes the morphological changes during embryonic development and pre-hatching organ development of Octopus hubbsorum, a species with a paralarval phase in its life cycle. The morphogenesis of O. hubbsorum begins simultaneously with the first reversion, a typical characteristic of octopuses, along with the development of the embryonic shape and structure. However, this species hatches with only three well-developed suckers. Organogenesis starts after the first embryonic reversion, with the development of the eyes, optic lobes, digestive gland, arms, and mantle. The branchial and central hearts show optimal development before the second reversion. The ink sac develops in the late stages (after the second reversion), while the stomach and crop are evident only after hatching and continue to develop until the first feeding. Newly hatched organisms show a complete development of the nervous, respiratory, circulatory, and integumentary systems. During the paralarval phase, O. hubbsorum undergoes major morphological and physiological changes until it reaches the subadult phase and develops the reproductive organs. This study highlights important organogenic differences compared to species with planktonic and benthic hatchlings. Further studies are needed in species with different life strategies to expand our knowledge of the developmental biology of cephalopods.
Journal Article
Morphology, Histology, and Transcriptome Analysis of Gonadal Development in Octopus minor (Sasaki, 1920)
Octopus minor is an economically important species, but little is known about the histological pattern and regulatory mechanisms during gonadal development. In this study, we investigated the annual changes in total body weight (TW), gonad somatic index (GSI), gonadal histological features, and transcriptome of O. minor. The results indicated that both females and males showed a similar TW trend. The GSI peaked in June in females, while it remained constant at around 3% in males. Nine and four histological stages were observed in ovaries and testes, respectively. Our field sampling results implied that O. minor might have overwintering periods for both eggs and larvae. Transcriptome analysis revealed that a total of 1095 and 2468 genes were significantly expressed during ovarian and testicular development, separately. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis displayed that 126 GO terms and 5 KEGG pathways were significantly enriched in the ovarian group of advanced vitellogenic oocytes vs vitellogenic oocytes (AVO vs VO). The pathways “Ribosomal”, “Cell cycle”, and “Progesterone-mediated oocyte maturation” were predicted to promote yolk deposition. Additionally, the testicular comparison group of spent vs mature (Spent vs Mature) showed significant enrichment in 674 GO terms and 13 KEGG pathways, suggesting that energy metabolism and cell repair pathways may be involved in the spermatogenesis process. This work revealed the development process of the gonads and shed light on the potential regulatory pathways of O. minor, providing novel insights and laying a molecular basis for artificial breeding.
Journal Article
The growth and population dynamics of Octopus insularis targeted by a pot longline fishery in north-eastern Brazil
The population dynamics of the stout reef octopus, Octopus insularis fished with longlines of pots in mid-shelf waters of north-eastern Brazil was studied based on fishermen's logbooks and onboard monthly fishing trips from September 2009 to August 2010. Specimens marked with oxytetracycline kept in tanks for up to 21 days provided evidence of the daily deposition of growth increments in the lateral wall of the upper beaks. Sampled specimens weighed 50–1280 g and had 43–172 daily growth increments. Compared with congeneric species from higher latitudes, O. insularis grows faster and has a shorter longevity in the north-eastern Brazil tropical environment. Total catches and catch-per-unit effort were substantially higher in the dry season, with less wind and cooler temperatures. The presence of larger specimens was seasonal, correlated with the chlorophyll-a levels recorded six months earlier. The year-round presence of mature females and males, spawned females, and egg masses attached to the pots, were considered evidence of migration of small and young specimens from coastal areas towards the 20–40 m depth range for reproduction. Annual landings attained ~200 tonnes (2005–2010). Although recent landing statistics are missing, fishermen interviewed in 2021 claimed that the fishery was still profitable. It is suggested that, despite the lack of management, the fast growth, year-round reproduction and limited market for this relatively small octopus, prevented the fishery from collapse and reinforces the current view of the high resilience of cephalopod fisheries.
Journal Article