Tag Archives: HYPNO

Meeting a famous gelatinous neighbour: Bathykorus bouilloni

Every now and then, a hydrozoan species will make the headlines because of the problems it creates for humans in a particular location. Hydrozoan jellyfish may bloom unexpectedly, transforming the water into a gelatinous soup, stinging people and fish in the process, while some hydroids have a tendency togrow massively in places where they are not wanted. There are others that end up in the news because they produce some unusual protein, or have a peculiar life cycle that could lead to important findings in the fields of medicine or ecology.

Then there is Bathykorus bouilloni, a hydrozoan jelly that has gotten some media attention due to its resemblance to an extremely famous movie character.

This is the original photograph by of a live specimen included in the description of the species, next to a pic of its look-alike. Photo of the jelly: Kevin Raskoff

This is the original photograph of a live specimen included in the description of the species, next to a pic of its look-alike. Photo of the jelly: Kevin Raskoff

This jellyfish was described in 2010 by Dr. Kevin Raskoff, who gave it its appropriate name. Bathykorus is a combination of Bathy (from bathus, meaning depth or deep in Greek) and korus (also from Greek, meaning helmet), and it refers to the deep-sea habitat of the species, as well as to the helmet-like shape of the bell (like that of an intergalactic villain). The word bouilloni in the name of this critter is a tribute to Dr. Jean Bouillon (1926-2009), one of the most prolific authors in Hydrozoan biology in the 20th century.

The species has been known to science only for some years, and indeed very few people may have seen it alive, but this does not necessarily mean that it is an uncommon animal: in fact, it may be extremely abundant in some places and is perhaps one of the most common species living at certain depths in the Central Arctic Ocean.

The peach-coloured spots in this medusa are most likely the remnants of its last meal. Photo: Aino Hosia

The wide circular mouth of this animal (a characteristic shared with many other jellyfish in the Order Narcomedusae) is best seen from above. Photo: Aino Hosia

We at the HYPNO project are happy to have found this charismatic species off Svalbard, and even more so when it was possible to barcode it through NorBOL!

-Luis

References

Antsulevich, A. E. (2015). Biogeographic and faunistic division of the Eurasian Polar Ocean based on distributions of Hydrozoa (Cnidaria). Journal of the Marine Biological Association of the United Kingdom 95(08): 1533-1539.

Raskoff, K. A. (2010). Bathykorus bouilloni: a new genus and species of deep-sea jellyfish from the Arctic Ocean (Hydrozoa, Narcomedusae, Aeginidae). Zootaxa 2361(1): 57-67.

Hunting for jellyfish (and some hydroids) with the SponGES Project

Picking out interesting specimens from the catch

Any opportunity to be in the sea is a good opportunity to go jelly-hunting, and the recent participation of HYPNO on a research cruise with the SponGES Project on RV Kristine Bonnevie this late April – early May was no exception!

To begin with, we got the chance to sample some hydromedusae and siphonophores with the plankton net in Bømlafjord. As usual, towing the net slowly (~0.3 ms^-1) resulted in happy jellies (they get damaged if the net is towed too fast!) that sometimes can be identified with ease. Over 15 different species of pelagic hydrozoans (plus some ctenophores and Tomopteris worms) were present in this vertical tow, with some nice looking critters such as the Eutonina indicans and Leuckartiara octona medusae shown below.

Eutonina indicans

Leuckartiara sp.

But not only hydromedusae and siphonophores showed up this time; we also got our hands on benthic samples from grabs and trawls, and found hydroids growing on rocks and other sea creatures (mostly sponges and sea squirts). Abietinaria abietina and Sertularella gayi (pictures below) are among the most common hydroids observed so far, and they were hosting a whole bunch of other hydrozoan species growing on top of them: real mini animal forests from the Norwegian waters!

Abietinaria abietina

Sertularella gayi

-Luis

Door #12: Plankton sampling with a vertebrate view!

HYPNO participating on an Arctic cruise by the Institute of Marine Research on RV Helmer Hanssen 17 Aug – 7 Sep 2015.

Most of the pelagic hydrozoans for HYPNO are collected with simple plankton nets, in the case of this Arctic cruise the double one you see in the picture. The net is towed vertically from above the bottom to the surface, bringing with it a representative sample of plankton – inclusive hydromedusae and siphonophores – from the entire water column. Standard plankton nets are generally lowered and retrieved at a speed of ~0.5 ms^-1.

This particular station in the Arctic basin was over 2000 m deep, which means that a single tow takes more than an hour to complete. Sometimes waiting for the sample to come up can get a bit tedious – not at this station, though! With this beauty turning up right outside the hangar opening, the wait didn’t feel long at all!

-Aino

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

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.