29 January 2008


DaleksI can honestly say I never expected this.

Dawn of the Crayleks!

It's a story featuring Marmorkrebs from The Files of Hydrogen Guy!

Part I
Part II
Part III

Thanks to Günter Vogt for the tip!

Note to Americans and mundanes: "Crayleks" pay homage to the Daleks (pictured), evil aliens from the BBC television series Doctor Who.

22 January 2008

Vogt, 2007

Vogt G. 2007. Exposure of the eggs to 17α-methyl testosterone reduced hatching success and growth and elicited teratogenic effects in postembryonic life stages of crayfish. Aquatic Toxicology 85(4): 291-296. http://dx.doi.org/10.1016/j.aquatox.2007.09.012


Testosterone is regularly found in the tissues of decapod crustaceans. Although this vertebrate-type sex hormone is not the principal factor of sex differentiation in crustaceans, it was shown to be capable of acting on the reproductive organs of shrimps and crabs. In the present study I have exposed developing eggs and stage 5 juveniles of the parthenogenetic all female marbled crayfish to 17α-methyl testosterone in order to test whether in freshwater crayfish sex can be changed from female to male by this androgen. MT did not elicit sex change, neither when administered during embryonic development nor during juvenile stage 5, the main period of proliferation of the oocytes. However, exposure to 100 μg/L MT from 64% to 84% embryonic development resulted in prolonged embryonic development, reduced hatching success, reduced growth of the juveniles, and severe malformations of the appendages in the juveniles. The marbled crayfish is recommended to be considered for toxicity tests due to its easy culture in the laboratory and its genotypical uniformity.

Keywords: methyl testosterone • marbled crayfish • toxicity • teratogenicity • ovarian development • sex differentiation

17 January 2008


Aquatic Habitats esearch aquariaWhat would an ideal Marmorkrebs rearing system look like?

Housing Marmorkrebs poses interesting problems, not the least of which is because Marmorkrebs reproduce so quickly. Using regular aquariums of the sort commonly found in pet stores certainly works, but can take up a lot of bench space. There may be a lot to be learned from zebrafish and Xenopus researchers, who are numerous enough that there are specific aquarium systems dedicated to housing large numbers of animals, collecting offspring, etc.

Aquatic Habitats offers some interesting systems (pictured). Our department has been using a benchtop system to house invertebrates for teaching purposes, and it is a decided improvement over lots of individual little tanks.

Another company worth looking into is Aquatic Eco-Systems, which has a variety of supplies. I'm particularly fond of their acrylic tanks, which I am currently using to house Marmorkrebs. The tanks are lightweight, making them much easier to move around. They are much less susceptible to cracking.

As the Marmorkrebs community grows, it will probably be important to work with these sorts of businesses to develop a standard set-up for someone who wants to establish a Marmorkrebs colony for research.

07 January 2008

SICB 2008 review

San Antonio skylineTo anyone who heard about this page at the recent SICB meeting in San Antonio -- welcome!

The SICB meeting was a far more eventful meeting for me personally than I expected. I hadn't fully realized the extent of the decapod crustacean contingent that would be there. It was really wonderful for me to meet a lot of people that I knew only by their published papers. Being a neuroethologist, I usually go to neurobiology and animal behaviour kinds of meetings, and hadn't really interacted with the crustie researchers at conferences very often before.

I had a chance to talk to a lot of people about Marmorkrebs, and gleaned some news, both good and bad. The good news was to learn of another paper about Marmokrebs coming out in The Journal of Experimental Biology in the next few months. The abstract will be posted here when it is published, as usual.

The bad news -- and it is very bad -- is that Marmorkrebs have now been found in Madagascar. Crayfish are harvested quite extensively there, as you can see in the video below, from the WWF.

While Marmokrebs are wonderful research animals, their potential as pests is just as great.