SIGNAL CRAYFISH

Fascinating facts about the SIGNAL CRAYFISH

• When signal crayfish arrive in a new basin they leave behind roughly three-quarters of their natural parasites and predators, a phenomenon called the Enemy Release Hypothesis. Coupled with higher aggression than rivals like the spiny cheek crayfish, this parasite-free boost fuels faster population growth and sharper competitive edges over native species.
• Signal crayfish can grow as long as a school ruler, reaching up to 20 cm (8 in) and tipping the scales at 110 g when their carapace hits 70 mm. Most adults sit between 6-9 cm (2.4-3.5 in) and weigh about 60 g at 50 mm.
• Introduced to Europe in 1960, signal crayfish have colonised 27 countries by 2009, making them the continent's most widespread invasive freshwater crayfish. Their rapid spread shows how a single species can push native crayfish toward extinction.
• Signal crayfish are night-shifters: in a controlled 12-hour light/12-hour dark cycle, 72 % of their movements happen after the lights go out. This nocturnal habit likely helps them dodge visual predators.
• Exposure to the herbicide metazachlor (MTZ) jolts signal crayfish into a rapid heart-rate spike and bursts of movement, whereas the chemicals terbuthylazine (TER) and thiacloprid (TCL) produce no measurable physiological response.

Sources

Every fact above was checked against these pages, and kept only where one of them states it.

• Wikipedia

At a glance

About the SIGNAL CRAYFISH

In the quiet, sun-dappled depths of European rivers, the signal crayfish moves with deliberate, sideways intent, its vibrant blue claws snapping softly as it navigates the hidden world of rocks and weed. With a gentle, almost languid pace, it probes the riverbed for unsuspecting morsels, its beady eyes watchful for the slightest flicker of movement. As it glides through the water, the signal crayfish embodies a serene, unhurried mastery of its domain, a true monarch of the river's secret places.

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