Tag Archives: siphonophores

Guest researcher: Eric

Eric, from the Federal University of ABC, visited the University Museum in November. We asked him about his time in Bergen examining some of the least common species of siphonophores in the collections and this is what he told us:

My name is Eric Nishiyama, and I am a PhD student from Brazil. The main focus of my research is the taxonomy and systematics of siphonophores, a peculiar group of hydrozoans (Cnidaria, Medusozoa) notorious for their colonial organization, being composed of several units called zooids. Each zooid has a specific function within the colony (such as locomotion, defense or reproduction) and cannot survive on its own.

Fig_1. I had the opportunity to examine both ethanol- and formalin-fixed material from the museum. For morphological analyses, specimens preserved in formalin are preferable because ethanol-fixed individuals are usually severely deformed due to shrinkage.

Understanding how zooids evolved could provide major insights on the evolution of coloniality, which is why I am looking at the morphology of the different types of zooids. In this sense, siphonophore specimens available at museum collections provide valuable information for visiting researchers such as myself.

During my short stay at the University Museum of Bergen in November, I was able to examine a few siphonophore samples deposited at the museum’s collections. By examining the specimens under a stereomicroscope, and using photography and image processing tools, I was able to gather a lot of information on the morphology of several species.

Fig_2. Documenting the morphology of the nectophores of Rudjakovia plicata (left) and Marrus or-thocanna (right) was particularly interesting because these species are not commonly found in museum collections.

Fig_3. Other ‘unusual’ siphonophores that I was able to examine were Crystallophyes amygdalina (left) and Heteropyramis maculata (right).

Fig_4. Some large nectophores of Clausophyes preserved in formalin.

The data obtained will allow me to score morphological characters for a phylogenetic analysis of the whole group, and hopefully will help me revise the group’s taxonomy.

– Eric

Door #3: Prepare to be HYPNOtized

One of this year’s new projects at the Invertebrate collections is HYPNO – Hydrozoan pelagic diversity in Norway, funded by the Norwegian Taxonomy Initiative.

A selection of photos depicting some of the species encountered so far in the project

A selection of photos depicting some of the species encountered so far in the project

Hydrozoa are a class of cnidarians, the pelagic representatives of which include hydromedusae as well as colonial siphonophores and porpitids. They are thus “cousins” to the more familiar larger scyphozoan jellyfish such as the moon jelly or the lion’s mane jelly. The size of pelagic hydrozoans ranges from small medusae of less than 1 mm to siphonophore colonies reaching several meters in length. They are mostly predators that use their tentacles and stinging cells to catch other zooplankton or even fish larvae. Most of the time they go largely unnoticed by the public, but at times they can form blooms and deplete zooplankton as well as cause problems for aquaculture and fisheries or sting bathers.

The aim of HYPNO is to chart, document and DNA-barcode the diversity of hydromedusae and siphonophores occurring in Norway. Gelatinous zooplankton, including hydrozoans, has been generally less studied than their crustacean counterparts, and we know less about their diversity. This is due to several challenges in studying them. First of all, many pelagic hydrozoans, particularly the colonial siphonophores, are very fragile and often damaged during sampling with standard plankton nets. This can make it difficult to identify them. Secondly, preserving hydromedusae and siphonophores for later work is problematic. For morphological studies, they are best preserved in formalin, since most other fixatives used for zooplankton -including ethanol- cause distortion and shrinkage of their gelatinous bodies, rendering the animals impossible to identify. Formalin fixation, however, hinders further genetic work.

To overcome these practical problems, HYPNO uses gentle collection methods to obtain specimens in good condition. Collected samples are immediately examined for hydrozoans, and the live animals are identified and documented with photos before they are fixed in ethanol for DNA barcoding of CO1 and 16S sequences.

So far, HYPNO has participated on two cruises by the Institute of Marine Research: to the North Sea and Skagerrak on RV Johan Hjort 24 Apr – 4 May 2015 and to the Arctic Ocean and Fram Strait on RV Helmer Hanssen 17 Aug – 7 Sep 2015. So far, 34 species have been photographed and sampled for DNA. Here is a selection of pictures depicting some of the species encountered during these surveys.

You can read more about HYPNO at http://data.artsdatabanken.no/Pages/168312.