Wonderful World of Mollusca; What Are We Looking For? - Heather Judkins
For DEEPEND, I am one of the taxonomists that identify the cephalopods (squid and octopus) that are collected from the MOCNESS nets. I am also collecting two other mollusc groups, pteropods (Sea Butterflies) and heteropods (Sea Elephants). Once animals are identified, tissue could go to one or more of the following places for further DEEPEND study: Stable isotope analysis (examples food web interactions among fauna), PAH (studying possible contaminants), or genetic barcoding for species identification verification and genetic diversity analysis.
Photo 1: A Sea Elephant, Carinaria sp.
Photo 2: A sample of Sea Butterflies (pteropods)
One of the advantages of using the MOCNESS is that we can collect organisms at discreet depths to analyze patterns on a fine scale. All focus animals: fishes, crustaceans, gelatinous organisms, and cephalopods are examined to piece together a more complete picture of the midwater column dynamics as they all contribute to the carbon moving from the surface waters to the deep-sea floor.
Team Mollusca are looking at vertical migration patterns for our three groups. Past studies on cephalopod vertical migration involve very few individuals per species so it is important to make the most of the large collection we have to further analyze these patterns. Our findings suggest that there is no one set vertical migration pattern by group but the patterns differ by species. For example, deep-sea pelagic octopods and the Vampire Squid are not found above 600m in the water column while the Moon Squid and Firefly squid move from the mesopelagic (200-1000m) to the epipelagic (0-200m) nightly, presumably for feeding purposes. We are noticing similar patterns in the heteropods, some migrate upwards and some do not. Pteropod analysis is underway at this time, stay tuned!
Here are some of the molluscs that are migrators and non-migrators,
Non-migrators: Japetella diaphana and Vampyroteuthis infernalis
Migrators: Selenoteuthis scintallins and Pterygioteuthis sp.