13 May 2022

Convicted by crayfish

Super quick because I’m in the middle of something, but I have to share this new story of a woman convicted of selling marbled crayfish in the United States.



Update, 18 May 2022: I never, e er, thought I would see the day when Marmorkrebs would be mentioned in a US Department of Justice press release. The press release contains more details of the scale of the operation.

Between August 2020 and June 2021, (Alison)  Spaulding sold marbled crayfish in 96 different transactions to buyers in 36 states for approximately $2,812.

According to The Guardian article linked above, Spaulding faces “ faces a maximum penalty of a year in prison and up to $100,000 in fines, although a federal judge is set to consider a lesser penalty under a plea deal.

19 April 2022

Bohman and colleagues 2022

Crayfish News
Bohman P, Edsman L, Mrugała A. 2022. Is this a Swedish signal crayfish or an alien marbled crayfish? Crayfish News 44(1): 1, 3-6. https://pub.epsilon.slu.se/27549/1/bohman-p-et-al-220414.pdf


Without abstract. Edited excerpt:

Marble-coloured signal crayfish may superficially look similar to another non-native crayfish species, the Marmorkrebs (the marbled crayfish, Procambarus virginalis), and may therefore be incorrectly identified as that species. Both crayfish species are on the European Union’s list of invasive alien species of Union’s concern (EU regulation 1143/2014) and thus highly unwanted in Sweden. The first illegally introduced Marmorkrebs in natural waters in Sweden was found in 2012. During 2013, several additional marble-coloured morphs of juvenile signal crayfish were discovered in Sweden. Therefore, to properly manage invasive alien species and to take correct and swift mitigation actions, it is imperative to have tools for quick and unambiguous species identification.

26 March 2022

Retained European Union law says you can’t retain Marmorkrebs in the United Kingdom

Dalek with Union Jack livery
I ran across this article of “pets you can’t have in the United Kingdom” and was a little surprised to see Marmorkrebs on the list. It is banned, along with four other crayfish species (Louisiana red swamp crayfish, signal crayfish, spiny-cheek crayfish, and virile crayfish).

It turns out the regulatory situation in England and Wales (but not Scotland or Northern Ireland?) is a little complicated.


Marmorkrebs were banned in 2016 as part of a European Union intiative. When the United Kingdom left the European Union, the regulations against Marmorkebs stayed as part of “retained EU law.” 

While the government website lists exemptions that people “may” be able to invoke to keep existing pets, it seems none of them would apply to Marmorkrebs. In particular, the “grandfather clause” allowing people to keep existing pets should not apply since Marmrokrebs don’t live as long as the regulations have been in effect.

I also have to snicker a bit about the rule that says if you have one of these animals, you must not let it reproduce. I’m not sure how you are supposed to prevent that in a parthenogenetic animal.

External links


The animals banned as pets in the UK - complete list


Invasive non-native (alien) animal species: rules in England and Wales


Form CRAY2: Application for a licence to keep non-native crayfish

18 March 2022

Katayama and colleagues 2022

COver to journal bioorganic Chemistry
Katayama H, Toyota K, Tanaka H, Ohira T. 2022. Chemical synthesis and functional evaluation of the crayfish insulin-like androgenic gland factor. Bioorganic Chemistry 122: 105738. hhttps://doi.org/10.1016/j.bioorg.2022.105738




Insulin-like androgenic gland factor (IAG) from the marbled crayfish Procambarus virginalis is an insulin-like heterodimeric peptide composed of A and B chains and has an Asn-linked glycan at the B chain. IAG is considered to be a male sex hormone inducing the sex differentiation to male in decapod crustacean, although there is no report on the function of IAG peptide in vivo. In order to characterize P. virginalis IAG, we chemically synthesized it and evaluated its biological function in vivo. A and B chains were prepared by the ordinary solid-phase peptide synthesis, and three disulfide bonds were formed regioselectively by dimethyl sulfoxide oxidation, pyridylsulfenyl-directed thiolysis and iodine oxidation reactions. An IAG disulfide isomer was also prepared by the same manner. Circular dichroism spectral analysis revealed that the disulfide bond arrangement affected the peptide conformation, which was similar to the other insulin-family peptides analyzed so far. On the other hand, the glycan moiety attached at the B chain had no effect on the peptide secondary structure. Injection of the synthetic IAG and its disulfide isomer to female crayfish did not induce male characteristics on the external morphology, but both peptides suppressed the oocyte maturation in vivo. These results suggest that IAG has a pivotal role on the suppression of female secondary sex characteristics.


Keywords: Insulin-like androgenic gland factor •  Procambarus virginalis • peptide synthesis • masculinization

Synthetic insulin-like androgenic gland factor suppressed oocyte formation in marbled crayfish

24 February 2022

Sentis and colleagues 2022

Cover of journal Ecology and Evolution
Sentis A, Veselý L, Let M, Musil M, Malinovska V, Kouba A. 2022. Short-term thermal acclimation modulates predator functional response. Ecology and Evolution 12(2): e8631. https://doi.org/10.1002/ece3.8631




Phenotypic plastic responses to temperature can modulate the kinetic effects of temperature on biological rates and traits and thus play an important role for species adaptation to climate change. However, there is little information on how these plastic responses to temperature can influence trophic interactions. Here, we conducted an experiment using marbled crayfish and their water louse prey to investigate how short-term thermal acclimation at two temperatures (16 and 24°C) modulates the predator functional response. We found that both functional response parameters (search rate and handling time) differed between the two experimental temperatures. However, the sign and magnitudes of these differences strongly depended on acclimation time. Acclimation to 16°C increased handling time and search rate whereas acclimation to 24°C leads to the opposite effects with shorter handling time and lower search rate for acclimated predators. Moreover, the strength of these effects increased with acclimation time so that the differences in search rate and handing time between the two temperatures were reversed between the treatment without acclimation and after 24 h of acclimation. Overall, we found that the magnitude of the acclimation effects can be as strong as the direct kinetic effects of temperature. Our study highlights the importance of taking into account short-term thermal plasticity to improve our understanding of the potential consequences of global warming on species interactions.

Keywords: None provided.


Open access

11 February 2022

Kaliszewicz and colleagues, 2022

The European Zoological Journal cover
Kaliszewicz A, Karaban K, Sierakowski M, Maciaszek R, Kur M, Pyffel Z, Wolny L, Chmiel K, Łuciuk P, Rusin P, Kowalczyk K. 2022. Effect of dietary supplementation with fatty acids on growth, survival, and fatty acid patterns in Procambarus clarkii and Procambarus virginalis: the first comparison of two invasive crayfish species. The European Zoological Journal 89(1): 123-134. https://doi.org/10.1080/24750263.2022.2030420




The red swamp crayfish, Procambarus clarkii, and the marbled crayfish, Procambarus virginalis, are invasive species expanding their ranges on a global scale. Their spread is favored by the fact that these crayfish are also aquaculture species of great economic importance (P. clarkii) or promising prospects in this regard (P. virginalis). This study represents the first attempt to assess the impact of diet supplementation with fatty acids on growth, survival, and fatty acid content in these crayfish species, as well as the first record of fatty acid patterns in the obligate parthenogenetic marbled crayfish. Our results showed that supplementation with saturated palmitic acid increased P. clarkii survival, which has not previously been reported for crustaceans. This positive effect on the part of palmitic acid supplementation was not observed for P. virginalis individuals. Marbled crayfish had significantly higher survival rates than red swamp crayfish regardless of the diet used. The growth of both species was not affected by fatty acid supplementation. Our study indicated that young marbled crayfish had a poorer fatty acid profile than juvenile conspecifics and red swamp crayfish. Fatty acid supplementation and type of diet significantly affected the fatty acid composition in the crayfish tissues. There was an increase in unsaturated α-linolenic acid for P. clarkii and palmitic acid for P. virginalis. Palmitic acid quantitatively dominated in both species regardless of the experimental treatment, with the exception of juvenile P. virginalis, which was fed an oligochaete diet rich in EPA. 


Keywords: red swamp crayfish • marbled crayfish • diet supplementation • saturated fatty acids

05 February 2022

Vogt 2022

The Science of Nature cover
Vogt G. 2022. Studying phenotypic variation and DNA methylation across development, ecology and evolution in the clonal marbled crayfish: a paradigm for investigating epigenotype-phenotype relationships in macro-invertebrates. The Science of Nature 109(1): 16. https://doi.org/10.1007/s00114-021-01782-6


Animals can produce different phenotypes from the same genome during development, environmental adaptation and evolution, which is mediated by epigenetic mechanisms including DNA methylation. The obligatory parthenogenetic marbled crayfish, Procambarus virginalis, whose genome and methylome are fully established, proved very suitable to study this issue in detail. Comparison between developmental stages and DNA methylation revealed low expression of Dnmt methylation and Tet demethylation enzymes from the spawned oocyte to the 256 cell embryo and considerably increased expression thereafter. The global 5-methylcytosine level was 2.78% at mid-embryonic development and decreased slightly to 2.41% in 2-year-old adults. Genetically identical clutch-mates raised in the same uniform laboratory setting showed broad variation in morphological, behavioural and life history traits and differences in DNA methylation. The invasion of diverse habitats in tropical to cold-temperate biomes in the last 20 years by the marbled crayfish was associated with the expression of significantly different phenotypic traits and DNA methylation patterns, despite extremely low genetic variation on the whole genome scale, suggesting the establishment of epigenetic ecotypes. The evolution of marbled crayfish from its parent species Procambarus fallax by autotriploidy a few decades ago was accompanied by a significant increase in body size, fertility and life span, a 20% reduction of global DNA methylation and alteration of methylation in hundreds of genes, suggesting that epigenetic mechanisms were involved in speciation and fitness enhancement. The combined analysis of phenotypic traits and DNA methylation across multiple biological contexts in the laboratory and field in marbled crayfish may serve as a blueprint for uncovering the role of epigenetic mechanisms in shaping of phenotypes in macro-invertebrates.


Keywords: phenotype • development • DNA methylation • ecology • evolution • marbled crayfish