25 September 2018

Göpel and Wirkner, 2018

Göpel T, Wirkner CS. 2018. Morphological description, character conceptualization and the reconstruction of ancestral states exemplified by the evolution of arthropod hearts. PLOS ONE 13(9): e0201702. https://doi.org/10.1371/journal.pone.0201702


Arthropods are the most species-rich taxon within Metazoa and have gone through major evolutionary changes with regard to body organization. Arthropod hearts and their associated vascular systems are thus morphologically highly disparate: while some arthropods exhibit very powerful hearts and complex vascular systems, other arthropods do not possess any kind of vascular system or heart at all. A comprehensive study investigating the structure of arthropods hearts has never been undertaken. In this study, we therefore investigate the hearts of 34 species from all major arthropod groups using various imaging techniques (confocal laser scanning microscopy, micro-computed tomography, histology) and describe them by addressing different aspects of heart morphology, e.g. the structure of the myocard or the composition of ostia. In a next step, we conceptualize 18 characters related to heart morphology and their respective character states and–using additional data from the literature–score a matrix for a total of 45 species from 38 supraspecific taxa. We map the characters onto prevailing phylogenetic hypotheses and perform parsimony-based ancestral state reconstruction to trace the evolutionary transformations undergone by arthropod hearts. An exploration of the character concepts (as explanatory hypotheses) reveals ontological peculiarities of character statements that clearly distinguish them in terms of ontological status from descriptive statements (i.e. descriptions of morphemes). The implications of these findings influence the interpretation of ground patterns as explanations. This first phylogenetic approach to heart morphology in the arthropod ground pattern reveals numerous new putative synapomorphies and leads to a reconsideration of the morphology of circulatory systems in early arthropods. Hypotheses on the evolution of hearts in (Pan-) Arthropoda are illustrated and discussed.

Keywords: None provided.

24 September 2018

Crayfish crimes 2

I mentioned a couple of weeks back that an American man had been convicted for selling and exporting crayfish as pets. Another case came to attention recently. An Australian man was convicted and fined AUD$8,550 for catching the world’s largest freshwater invertebrate, Astacopsis gouldii. The crayfish is threatened and protected by law.

I mention this because protecting invertebrates is hard, and law enforcement on this sort of issue is rare. It’s encouraging to see.

Related posts

Crayfish crimes

External links

Largest ever fine for poaching giant freshwater crayfish

21 September 2018

Linzmaier and colleagues, 2018

Linzmaier SM, Goebel LS, Ruland F, Jeschke JM. 2018. Behavioral differences in an over-invasion scenario: marbled vs. spiny-cheek crayfish. Ecosphere 9(9): e02385. https://doi.org/10.1002/ecs2.2385


New species often invade ecosystems already dominated by previous invaders. Ornamental freshwater crayfish, particularly parthenogenetic marbled crayfish (Procambarus virginalis), increasingly establish in European water bodies where they interact with resident native and non-native species. Behavioral traits and behavioral syndromes can influence the outcome of these species interactions. The behavior of non-native crayfish is often studied in notorious invaders but rarely in new and emerging species, although those provide the best opportunity for management. Activity, aggressiveness, and boldness have repeatedly been associated with invasion success and species displacement. Further, crayfish can adapt their behavior after they have established in the new range. We investigated whether marbled crayfish can displace the widely established spiny-cheek crayfish (Orconectes limosus). Specifically, we compared their behavioral traits and evaluated whether these traits differ, using marbled crayfish populations from aquaria and the field and spiny-cheek crayfish from the field.We staged agonistic encounters, measured activity levels, and recorded the response to a simulated threat of both species and both origins (field and aquarium) in laboratory trials. We found that in agonistic encounters, marbled crayfish were on average more aggressive than spiny-cheek crayfish, even against larger opponents. Aggressiveness and activity were positively correlated, which is indicative for an aggression syndrome. Marbled crayfish from the field were less active than those from aquaria, but there was no difference in aggressiveness. Marbled crayfish often froze in response to a simulated threat, whereas spiny-cheek crayfish reacted either offensively or defensively. These results from the laboratory illustrate potentially important behavioral mechanisms behind crayfish over-invasions and show behavioral plasticity in a species where all known individuals are genetically identical. To better understand the invasion process in nature, the species’ reproductive biology and interactions with other members of the community should be considered. We conclude that the recent success of marbled crayfish in establishing new populations could be influenced by their behavioral flexibility and their potential to competitively persist in the presence of established invasive crayfish.

Keywords: aggression • behavioral flexibility • behavioral syndromes • behavioral variability • biological invasions • freshwater crayfish • shelter use • threat response

19 September 2018

The Maltese crayfish: A dozen invaded European countries

It was Germany, then Italy, then the Netherlands, then Hungary, then Croatia, then Slovakia, then Romania, then Sweden, then the Ukraine, then the Czech Republic, then Estonia, and now Malta.

Malta makes it an even dozen European countries where Marmorkrebs have been found in outdoors, according to a paper in press from Deidun and colleagues. This is not a few stray individuals, either. Some sites (visited in 2016 and 2017) had hundreds of individuals. I will add the paper to the collection of abstract on the blog once the final paginated version is published.

I have updated the map of Marmorkrebs introductions accordingly.

My only consolation is that at some point, I’m going to run out of European countries to add to the list. Marmorkrebs will be in all of them.


Deidun A, Sciberras A, Formosa J, Zava B, Insacco G, Corsini-Foka M, Crandall KA. Invasion by non-indigenous freshwater decapods of Malta and Sicily, central Mediterranean Sea. Journal of Crustacean Biology: in press. http://dx.doi.org/10.1093/jcbiol/ruy076

External links

Alien crayfish invade Malta’s valleys and watercourses
Alien crayfish have invaded Malta’s valleys, study finds

13 September 2018

Cover cray

Nice cover accompanying this blog post. It’s covering the Marmorkrebs genome paper that came out back in February, but better late than never! The photo is aces in any case.

External links

Decoding the mutant, all-female, self-cloning crayfish

Crayfish crimes

Prosecutions for anything to do with the aquarium trade is rare, but last week, news reported Justin Doyle Pierce, an American was prosecuted for selling crayfish as pets, in violation of the Lacey Act)

Pierce sold over $19,000 worth of crayfish illegally, and for this, he got a $500 fine, 20 hours of community service, and a year on probation. By my quick scan of the act, he could have received jail time and thousands of dollars in fines.

Is this sort of enforcement acting as a deterrent? It’s not clear. When someone can make that much money, the fine is little more than a clap on the wrist. The real penalty may not be the fine or the service, but the criminal record. Pierce wrote:

(T)his will result in my disqualification of future employment in areas related to wildlife and conservation.

External links

Feds pinch Camden County man for illegal crayfish sales
Overview of the Lacey Act (16 U.S.C. SS 3371-3378)
Lacey Act cases

Hossain and colleagues, 2018

Hossain MS, Patoka J, Kouba A, Buřič M. 2018. Clonal crayfish as biological model: a review on marbled crayfish. Biologia 73(9): 841-855. https://doi.org/10.2478/s11756-018-0098-2


Since the mid-twentieth century, numerous vertebrates and invertebrates have been used as model organisms and become indispensable tools for exploring a broad range of biological and ecological processes. Crayfish seem to be adequate models which resulted in their involvement in research. In the two decades since its discovery, ongoing research has confirmed that the marbled crayfish (Procambarus virginalis Lyko, 2017) is an ideal taxon in this regard, especially due to its almost continuous asexual reproduction providing a source of genetically identical offspring. This review provides an overview of the occurrence, biology, ecology, ethology, and human exploitation of marbled crayfish with primary focus on its use as a laboratory model organism as well as potential risks to native biota in case of its introduction. Genetic uniformity, ease of culture, and a broad behaviour repertoire fosters the use of marbled crayfish in epigenetics and developmental biology, as well as physiological, ecotoxicological, and ethological research. Marbled crayfish could be further exploited for basic and applied fields of science such as evolutionary biology and clonal tumour evolution. However, due to its high invasive potential in freshwater environments security measures must be taken to prevent its escape into the wild.

Keywords: model species • epigenetics • developmental biology • Procambarus virginalis • biological invasion

01 September 2018

Naboka and colleagues, 2018

Naboka A, Marenkov O, Kovalchuk J, Shapovalenko Z, Nesterenko O, Dzhobolda B. 2018. Parameters of the histological adaptation of Marmorkrebs Procambarus virginalis (Lyko, 2017) (Decapoda, Cambaridae) to manganese, nickel and lead ions pollution. International Letters of Natural Sciences 70: 24-33. https://doi.org/10.18052/www.scipress.com/ILNS.70.24


Manganese, lead and nickel are heavy metals, which are the primary fresh water toxic contaminants being in the most dangerous class of chemicals. Heavy metals cause functional disorders in the tissues and organs of hydrobionts, affecting their linear and weight indices, reproductive system, digestive and extraction organs. In our experiment on marbled crayfish Procambarus virginalis (Lyko, 2017) we studied the long-term effects of various concentrations of heavy metal ions on the physiological state and histostructure of tissues and organs. According to the results of research, it was found that among the studied heavy metals nickel ions influenced the weight indexes and mortality of crustaceans the most negatively. The results of morphometric studies on marbled crayfish indicate no significant differences between the control group and experimental one, but heavy metals influenced the form of the hepatopancerase lobes and the size of the lumen of the gland. Research on adipocytes of the connective tissue showed a significant difference between the size of cells under the influence of heavy metals. Dimensions of adipocytes fluctuated over a wide range from 144 μm2 to 537 μm2. In control group the adipocyte area was 406.96 μm2. Experimental studies of hemolymph showed that, under the influence of lead ions, a significant 1.4 times increase was observed in the area of hemolymph cells; when manganese and nickel were added, moderate decrease was observed in cells. It was found that under the influence of nickel, the area of round hyalinocytes has reduced by 1.7 times.

Keywords: Procambarus virginalis • glandulocytes • hepatopancreas • hemolymph • manganese • nickel • lead • crustaceans