Ghost shark

Abstract: The diets of Harriotta raleighana, Hydrolagus bemisi and Hydrolagus novaezealandiae were determined from examination of digestive tract contents from specimens sampled at depths of 219 to 876 m on the submarine ridge, Chatham Rise, New Zealand. All 3 species fed predominantly on benthic epifauna and infauna. Similarity percentages indicated the diet of H. raleighana was characterised by polychaetes and molluscs, H. bemisi by crabs and polychaetes, and H. novaezealandiae by crabs and sea urchins. Multivariate analyses using distance-based linear models found the most important predictors of diet variability were a categorical predictor for the subtropical front (STF) and bottom temperature. Cluster analysis of species subgroups indicated there was a greater similarity in diet between H. raleighana and H. bemisi, and between H. bemisi and H. novaezealandiae, in similar locations, than between subgroups of H. bemisi in different locations. Generalised additive models indicated that depth was the most important spatial predictor of research trawl survey catch rates, and depth separation was most pronounced between H. raleighana and H. novaezealandiae. Other significant predictors of diet variability included longitude, and fish length or weight. In all 3 species the diet of smaller fish included more polychaetes, small crustaceans and gastropods, and the diet of larger fish contained more decapod crustaceans. The primary factor determining niche separation among the 3 species appears to be depth and distribution rather than dietary specialisation.

Abstract: Two new species of chimaeroid fishes from the family Chimaeridae are described on the basis of morphological characters. The carpenter's chimaera is a large-bodied species of Chimaera distinguished from its congeners by massive head with blunt snout; firm, nondeciduous skin; purplish color; preopercular and oral lateral line canals branching together; and pelvic claspers that are divided for the distal one third of length, purple at the base with white fleshy tips. The pale ghost shark is a species of Hydrolagus distinguished from its congeners by a dorsal fin spine that reaches to the origin of the second dorsal fin when depressed; elongate second dorsal fin not indented along its length; preopercular and oral lateral line canals sharing a common branch; long, stout caudal filament; and pale silvery-gray coloration fading to white ventrally. The pale ghost shark has long been recognized as a new species from New Zealand, and formal taxonomic recognition of this species will prove important for fishery management.

Abstract: The vertebrate globin gene repertoire consists of seven members that differ in terms of structure, function and phyletic distribution. While hemoglobin, myoglobin, cytoglobin, and neuroglobin are present in almost all gnathostomes examined so far, other globin genes, like globin X, are much more restricted in their phyletic distribution. Till today, globin X has only been found in teleost fish and Xenopus. Here, we report that globin X is also present in the genomes of the sea lamprey, ghost shark and reptiles. Moreover, the identification of orthologs of globin X in crustacean, insects, platyhelminthes, and hemichordates confirms its ancient origin.

Abstract: Deep sea lobsters are highly valued for seafood and provide the basis of important commercial fisheries in many parts of the world. Despite their economic significance, relatively little is known about their natural diets. Microscopic analyses of foregut content in some species have suffered from low taxonomic resolution, with many of the dietary items difficult to reliably identify as their tissue is easily digested. DNA metabarcoding has the potential to provide greater taxonomic resolution of the diet of the New Zealand scampi (Metanephrops challengeri) through the identification of gut contents, but a number of methodological concerns need to be overcome first to ensure optimum DNA metabarcoding results. In this study, a range of methodological parameters were tested to determine the optimum protocols for DNA metabarcoding, and provide a first view of M. challengeri diet. Several PCR protocols were tested, using two universal primer pairs targeting the 18S rRNA and COI genes, on DNA extracted from both frozen and ethanol preserved samples for both foregut and hindgut digesta. The selection of appropriate DNA polymerases, buffers and methods for reducing PCR inhibitors (including the use of BSA) were found to be critical. Amplification from frozen or ethanol preserved gut contents appeared similarly dependable. The COI gene was found to be more effective than 18S rRNA gene for identifying large eukaryotic taxa from the digesta; however, it was less successfully amplified. The 18S rRNA gene was more easily amplified, but identified mostly smaller marine organisms such as plankton and parasites. This preliminary analysis of the diet of M. challengeri identified a range of species (13,541 reads identified as diet), which included the ghost shark (Hydrolagus novaezealandiae), silver warehou (Seriolella punctata), tall sea pen (Funiculina quadrangularis) and the salp (Ihlea racovitzai), suggesting that they have a varied diet, with a high reliance on scavenging a diverse range of pelagic and benthic species from the seafloor.