Abstract The contexts in which individuals demonstrate behavioural consistency or variability have been the subject of research focus. We studied exploratory and sheltering behaviour crayfish F. virilis to understand how these behaviours vary by sex reproductive readiness quantify repeatability behaviours. Crayfish were tested two sets three rounds, one summer non-reproductive season another au...

Male sexual differentiation in crustaceans is controlled by the androgenic gland (AG), a unique male endocrine organ that, in decapods, is located at the base of the 5th pereiopod. In these animals, the insulin-like androgenic gland hormone (IAG) is the major factor secreted from the AG to induce masculinization and maintain male characteristics. It has, however, recently been proposed that thi...

The parthenogenetic marbled crayfish (Procambarus spec.) has recently been introduced as a new preparation for neuroethological studies. Since isogeneity apparently limits inter-individual variation, this otherwise typical decapod species may be especially valuable for circadian studies. Locomotor activity of isolated marbled crayfish and agonistic activity of small social groups maintain circa...

New neurons are incorporated throughout life into the brains of many vertebrate and nonvertebrate species. This process of adult neurogenesis is regulated by a variety of external and endogenous factors, including environmental enrichment, which increases the production of neurons in juvenile mice and crayfish. The primary goal of this study was to exploit the spatial separation of the neuronal...

Intracellular fatty acid-binding proteins (FABPs) are small members of the superfamily of lipid-binding proteins, which occur in invertebrates and vertebrates. Included in this superfamily are the cellular retinoic acid-binding proteins and retinol-binding proteins, which seem to be restricted to vertebrates. Here, we report the cDNA cloning and characterization of two FABPs from hemocytes of t...

Invasive crayfish are a major threat to stream ecosystems, yet research has seldom identified successful ways of preventing their spread. Thirty-two stream sections were surveyed during 2000 and 2001 in the Santa Monica Mountains of southern California to determine the distribution of the invasive crayfish Procambarus clarkii. Streams with large barriers (waterfalls, culverts) often did not hav...

Crayfish are nocturnal animals that mainly rely on their chemoreceptors to locate food. On a crayfish scale, chemical stimuli received from a distant source are dispersed by an ambient flow rather than molecular diffusion. When the flow is weak or absent, food searching can be facilitated by currents generated by the animal itself. Crayfish employ their anterior fan organs to produce a variety ...

We demonstrate that the probability of the crayfish, P. clarkii, to tail flip in response to a touch on the dorsal tail fan is dependent on both the size and the behavioral state of the animal. Alterations in the animal's internal physical state, such as when the animal autotomizes its chelipeds, will cause larger-sized animals to tail flip; if they were not autotomized, then no tail flip respo...

Although the presence/absence of aquatic invertebrates using environmental DNA (eDNA) has been established for several species, inferring population densities has remained problematic. The invasive American signal crayfish, Pacifastacus leniusculus (Dana), is the leading cause of decline in the UK's only native crayfish species, Austropotamobius pallipes (Lereboullet). Methods to detect species...

The experiment was conducted to investigate the effects of artemia enriched with lipid emulsions containing highly unsaturated fatty acids on growth and survival of juvenile freshwater crayfish Astacus leptodactylus. Juvenile crayfish were fed artemia enriched with commercial emulsions (red pepper and olio ω3) and un-enriched artemia (control). The highest eicosapentaenoic acid (EPA) level was ...