HOST SWITCHING IN DICYEMIDS (PHYLUM DICYEMIDA).

Dicyemids (phylum Dicyemida) are the most common and most characteristic endosymbionts in the renal sacs of benthic cephalopod molluscs: octopuses and cuttlefishes. Typically, 2 or 3 dicyemid species are found in a single specimen of the host, and most dicyemids have high host specificity. Host-specific parasites are restricted to a limited range of host species by ecological barriers that impede dispersal and successful establishment; therefore, phylogenies of interacting groups are often congruent due to repeated co-speciation. Most frequently, however, host and parasite phylogenies are not congruent, which can be explained by processes such as host switching and other macro-evolutionary events. Here, the history of dicyemids and their host cephalopod associations were studied by comparing their phylogenies. Dicyemid species were collected from 8 decapodiform species and 12 octopodiform species in Japanese waters. Using whole mitochondrial cytochrome c oxidase subunit 1 (COI) sequences, a phylogeny of 37 dicyemid species, including 4 genera representing the family Dicyemidae, was reconstructed. Phylogenetic trees derived from analyses of COI genes consistently suggested that dicyemid species should be separated into 3 major clades and that the most common genera, Dicyema and Dicyemennea, are not monophyletic. Thus, morphological classification does not reflect the phylogenetic relationships of these 2 genera. Divergence (speciation) of dicyemid species seems to have occurred within a single host species. Possible host-switching events may have occurred between the Octopodiformes and Decapodiformes or within the Octopodiformes or the Decapodiformes. Therefore, the mechanism of dicyemid speciation may be a mixture of host switching and intra-host speciation. This is the first study in which the process of dicyemid diversification involving cephalopod hosts has been evaluated with a large number of dicyemid species and genera.

In an octopus's garden in the shade: Underwater image analysis of litter use by benthic octopuses.

Benthic octopuses have been widely documented in artificial shelters for decades, and this use is apparently increasing. Despite any possible positive effects, the use of litter as shelter could have negative implications. In this work, we aimed to elucidate the interactions of octopuses with marine litter, identifying types of interactions and affected species and regions. To achieve this, we obtained 261 underwater images from 'citizen science' records, and identified 8 genera and 24 species of benthic octopuses interacting with litter. Glass objects were present in 41.6% of interactions, and plastic in 24.7%. Asia presented the highest number of images, and most records were from 2018 to 2021. Citizen science provided important evidence on octopus/marine litter interactions, highlighting its value and the need for more investigations on the subject. This information is fundamental to help prevent and mitigate the impacts of litter on octopuses, and identify knowledge gaps that require attention.

Why Are Octopuses Going to Be the 'Poster Child' for Invertebrate Welfare?

Animal welfare consideration and actions are generally addressed to animals similar to us, predominantly large mammals. Invertebrates are neglected partly because they are unknown, though new exploration of the oceans has helped with this. Also, we know little about their ecology and welfare. This is gradually changing, and the octopuses are likely to be the first beneficiaries. Scientists are finding that cephalopods are far more intelligent than we thought, with the Cambridge Declaration of Consciousness suggesting they might possess this quality of mind. Partly as a result, the European Union has described and demanded good care for cephalopods such as the octopus in captivity. Public opinion has been swayed to approval by anecdotes of octopuses doing unusual actions, and by several recent books pointing out interesting and intelligent behavior of cephalopods. Aquariums have begun to feature octopuses for them. With this progress, welfare of invertebrate animals has begun to matter. While the octopuses will be the first animal group to benefit, they may pave the way for us to see that different does not mean unworthy of regard and welfare consideration.

Taxonomic assessment of species of the genus Octopus from the northeastern Pacific via morphological, molecular and morphometric analyses.

Species of the genus Octopus from the northeastern Pacific are ecologically and economically important; however, their taxonomy is confusing and has not been comprehensively assessed. In this study, we performed a taxonomic evaluation of these species considering the morphological characteristics of the original descriptions, a molecular analysis of partial COI-gene sequences, and a traditional morphometry analysis of nine body measurements. Several interesting findings were obtained with our results: for instance, we updated the diagnoses of some species by including characters such as the number of lamellae per demibranch and the presence of chromatophores in the visceral sac; we deposited partial COI-gene sequences of species that had not been incorporated into the GenBank repository; and according to the morphometric analysis, we confirmed that the lengths of arms I-IV are relevant to discriminate the species under study. The taxa evaluated were morphologically, molecularly and morphometrically well-delimited; however, features such as funnel organ shape and arm length proportions in regard to dorsal mantle length are either not included in the diagnosis of the genus Octopus or overlap with other genera. Hence, this information, combined with the results obtained from the molecular analysis, supports the generic re-assignation of two of the species evaluated.

Genetic structure of Octopus minor around Chinese waters as indicated by nuclear DNA variations (Mollusca, Cephalopoda).

Octopus minor is an economically important resource commonly found in Chinese coastal waters. The nuclear gene (RD and ODH) approach of investigation has not reported in this species. Rhodopsin (RD) and octopine dehydrogenase (ODH) genes were used to elaborate the genetic structure collected from eight localities ranging from the northern to the southern coast of China. In total, 118 individuals for the RD gene and 108 for the ODH were sequenced. Overall (RD and ODH) genes resulted in high (0.741±0.032; 0.805±0.038) haplotype and low nucleotide (0.01261±0.00165; 0.00747±0.00086) diversity. Molecular variance displayed higher values among the populations and lower values within the population where the fixation index FST denoted 0.880 and 0.584 in RD and ODH genes respectively. The Dongshan population clustered separately in a phylogenetic tree as in the haplotype networking assessment. The current data suggests that the Dongshan population needs separate management.

Infiltrated plaques resulting from an injury caused by the common octopus (Octopus vulgaris): a case report

Several species of octopus are considered venomous due to toxins present in the glands connected to their beak, which may be associated with hunt and kill of prey. Herein, we report an accident involving a common octopus (Octopus vulgaris) that injured an instructor during a practical biology lesson and provoked an inflamed infiltrated plaque on the hand of the victim. The lesion was present for about three weeks and was treated with cold compresses and anti-inflammatory drugs. It was healed ten days after leaving a hyperchromic macule at the bite site. The probable cause of the severe inflammation was the digestive enzymes of the glands and not the neurotoxins of the venom.

Infiltrated plaques resulting from an injury caused by the common octopus (Octopus vulgaris): a case report

Several species of octopus are considered venomous due to toxins present in the glands connected to their "beak", which may be associated with hunt and kill of prey. Herein, we report an accident involving a common octopus (Octopus vulgaris) that injured an instructor during a practical biology lesson and provoked an inflamed infiltrated plaque on the hand of the victim. The lesion was present for about three weeks and was treated with cold compresses and anti-inflammatory drugs. It was healed ten days after leaving a hyperchromic macule at the bite site. The probable cause of the severe inflammation was the digestive enzymes of the glands and not the neurotoxins of the venom.(AU)

Infiltrated plaques resulting from an injury caused by the common octopus (Octopus vulgaris): a case report.

Several species of octopus are considered venomous due to toxins present in the glands connected to their "beak", which may be associated with hunt and kill of prey. Herein, we report an accident involving a common octopus (Octopus vulgaris) that injured an instructor during a practical biology lesson and provoked an inflamed infiltrated plaque on the hand of the victim. The lesion was present for about three weeks and was treated with cold compresses and anti-inflammatory drugs. It was healed ten days after leaving a hyperchromic macule at the bite site. The probable cause of the severe inflammation was the digestive enzymes of the glands and not the neurotoxins of the venom.