Search

As per the FAO data, octopus identification is very limited in the species level at world fishery and also they are cryptic nature. On the other hand, Indonesia is one of the top ten highest octopus exporters. This study therefore aimed to determine the species of octopus based on phylogenetic analysis of mt-DNA COI. Octopuses were collected from nine different locations throughout Indonesia, i.e., Anambas, Bangka-Belitung, Cirebon, Karimunjawa, Tuban, Lombok, Buton, Wakatobi and Jayapura. Samples were mostly in the form of tentacles that were directly collected from fishermen. After being preserved in 96% ethanol, the sample was extracted in 10% chelexÒ, PCR amplification using Folmer’s primer then was further analysed by sequencing in Sanger methods. Of the 24 samples sequenced, the results recognized four species Octopodidae belongs to the three genera, named Amphioctopus aegina, Hapalochlaena fasciata, Octopus laqueus and Octopus cyanea. Mean pair-wise distances of within-species were ranged from 0 to 5.5 % and between-species was ranged from 12.9 to 15.8 %. This study distinctly confirmed the difference between genus Amphioctopus and Hapalochlaena (15.5 %), as also between O. laqueus and O. cyanea (12.9%) which was previously not completely distinguished. Although performing species identification using DNA sequences for shallow-water benthic octopus species is perhaps considered premature, this study indicated the possible application of COI sequences for species identification, thereby providing a preliminary dataset for future DNA barcoding of octopus, in particular for Indonesia waters.

Octopus is the most abundant genus in the family Octopodidae and accounts for more than half of the total cephalopod landing in neritic fisheries. A taxonomic problem still exists due to synonymous scientific names and limited genetic information. The cephalopod beak is a stable structure that allows an effective solution to the problem of the species and stock identification. Beak shape variation has been more widely considered than beak measurements in recent years. In this study, with the beak as the experimental material, we combined geometric morphometrics (GM) with machine learning methods and compared the discrimination results obtained by traditional and GM methods in four Chinese neritic octopus species (Amphioctopus fangsiao, Amphioctopus ovulum, Octopus minor and Octopus sinensis). According to our analyses, Octopus sinensis has the larger beak size [both upper beak (UB) and lower beak (LB)] than other species. The results of ANOVA showed that all beak measurements differed significantly among the four species. Significant differences in both UB and LB shapes among four species were identified in MANOVA analysis based on the GM method. The results of GM-based discriminant analysis were better than those of traditional measurements, and machine learning methods also showed the higher correct classification rates than linear discriminant analysis. GM is a useful method to reconstruct the shape cephalopod beak and can also effectively distinguish different species. We should improve classification accuracy with machine learning methods for determining species structure in the future.

The complete mitochondrial genomes of two important octopus species from the eastern Pacific were sequenced, obtaining their complete nucleotide sequences. Octopus mimus is the most important commercially catched species along the eastern Pacific, from Mexico to Chile, whereas ‘Octopus’ fitchi is a pigmy species with uncertain taxonomic genus. The mitogenomes of Octopus mimus and ‘Octopus’ fitchi were 15,696 and 15,780 base pairs (bp) in length with an A + T composition of 75.5% and 75.8%, respectively. Each genome contains 13 protein-coding genes, 22 tRNA genes, and two rRNA genes, as well as a control region. Gene order is maintained as reported for other species of the Octopodidae. The phylogenetic analysis based on the concatenated thirteen protein-coding genes confirms that O. mimus belongs to the genus Octopus, which is supported by the genetic distance (11–16%) whereas the position of ‘O’. fitchi within this group it is not supported. The analysis also indicated that the phylogenetic position of ‘O’. fitchi is closer to Callistoctopus than to the Cistopus or the Amphioctopus clades. Based on the tree topology and the high genetic distance observed (24–25%), we suggest that ‘O’. fitchi might represent a different genus.

The cephalopod fauna of the southwestern Atlantic is especially poorly-known because sampling is mostly limited to commercial net-fishing operations that are relatively inefficient at obtaining cephalopods associated with complex benthic substrates. Cephalopods have been identified in the diets of many large marine species but, as few hard structures survive digestion in most cases, the identification of ingested specimens to species level is often impossible. Samples can be identified by molecular techniques like barcoding and for cephalopods, mitochondrial 16S and COI genes have proven to be useful diagnostic markers for this purpose. The Amazon River estuary and continental shelf are known to encompass a range of different substrates with recent mapping highlighting the existence of an extensive reef system, a type of habitat known to support cephalopod diversity. The present study identified samples of the cephalopod fauna of this region obtained from the stomachs of red snappers, Lutjanus purpureus, a large, commercially-important fish harvested by fisheries using traps and hook-and-line gear that are capable of sampling habitats inaccessible to nets. A total of 98 samples were identified using molecular tools, revealing the presence of three squid species and eight MOTUs within the Octopodidae, representing five major clades. These include four known genera, Macrotritopus, Octopus, Scaeurgus and Amphioctopus, and one basal group distinct from all known octopodid genera described here as Lepidoctopus joaquini Haimovici and Sales, new genus and species. Molecular analysis of large predatory fish stomach contents was found to be an incredibly effective extended sampling method for biodiversity surveys where direct sampling is very difficult.

Amphioctopus ovulum (Sasaki, 1917) is a small to moderate-sized octopus, which can be identified by the iridescent violet ring present in the dark ocellus on the web between the bases of arms II and III. Comprehensive taxonomic review is required to fully characterise this species because the syntypes are missing and the description is insufficiently complete for modern octopod taxonomy. In this study, the species A. ovulum is redescribed with morphological and morphometric characters of 18 specimens collected from the coastal waters of China. The distribution of A. ovulum extends from the Gulf of Thailand, through Cambodia, Vietnam, Philippines, through the South China Sea and the East China Sea to Japan. The swollen terminal organ diverticulum and long spermatophores make it possible to distinguish A. ovulum clearly from A. rex and A. neglectus, species with similar morphological characters of violet rings. Moreover, three species of violet-ringed octopods were clearly differentiated by sequences of the partial mitochondrial genes COI and COIII. Three monophyletic clades resolved in phylogenetic trees. Amphioctopus rex and A. neglectus clustered into a sister taxon, and clustered with the remaining Amphioctopus species.

Taxonomic and ecological aspects of paralarval octopods from the Florida Current (Gulf Stream) waters off Fort Pierce, Florida are reported. Nine external morphological features were analysed in each specimen, including chromatophore patterns and meristic characters. The relative abundance of each species present in the collections made at standard stations [2–26 nautical miles (nmi) offshore at 2-nmi intervals; 1 nmi = 1.8520 km] was determined in relation to seasonal occurrence, depth of capture, distance offshore and time of day/night. The most common species in the samples was Octopus “vulgaris”, followed by Amphioctopus burryi and Macrotritopus defilippi (two morphs). Two forms could not be verified to species, but they most closely resemble Scaeurgus unicirrhus and “Octopus” joubini. The seasonal distribution of the most commonly captured species showed peak relative abundance in the summer months. Paralarval octopods were captured most frequently in the standard stations between 18 and 22 nmi (29.6...

Five Veined Octopus Amphioctopus marginatus (Taki), collected from Vizhinjam Bay in the Thiruvananthapuram District of Kerala, India were kept in aquariums to study their behaviour in captivity. Primary and secondary defence mechanisms studied included crypsis, hiding and escape behaviour. Deimatic behaviour was used by captive animals when camouflage failed and they were threatened. Crawling behaviour to escape from the aquarium was observed in all specimens. Stilt walking and bi-pedal locomotion were also observed. As a defence behaviour, A. marginatus used aquarium rocks to protect the soft underside of their bodies. A. marginatus demonstrated tool use of coconut shells to make protective shelters, carrying the shells for future use. A female specimen also selected a coconut shell for egg laying and performed parental care by continuously cleaning and aerating her eggs with her arms and by squirting jets of water over the eggs.