The European Scorpion Euscorpius flavicaudis (DeGeer, 1778) in Essex
provide a review of scorpions in Britain whilst reporting the present record. Before doing so, however,
some information on scorpions in general is likely to be of interest to readers.
Evolutionary history
The fi rst terrestrial scorpions are believed to have evolved from the Eurypteridae, or water scorpions,
between 425 and 450 million years ago during the Silurian epoch. The first scorpions were most
probably marine, and marine members of the family continued to exist until about 250 to 300 million
years ago. The first terrestrial species were to be found by about 340 mill ion years ago. As with most
arthropods, early scorpions produced some very large species and the largest fossils found so far
indicate about 1 metre as the maximum length (Brontoscorpio willsi). As scorpions arc entirely
predatory, they would not have been the first to make use of the new terrestrial habitat, and could
only move out of the sea after sufficient prey species had gone before them. These prey species
would most likely have been insects, arachnids and millipedes. The earliest known terrestrial scorpion
is Palaeopisthacanthus from the Upper Carboniferous. Some species still live near the sea, hunting
i n the littoral zone of the seashore keeping company with the crabs and periwinkles (e.g. Euscorpius
carpathicus).
Higher taxonomy
The first person to make a serious attempt to study scorpions was probably Francesco Redi who
wrote intelligently of his observations, in 1671. Following this, Pierre-Louis de Maupertius published
Experiences sur les Scorpiones in 1733. Linnaeus, in 1758, had scorpions as a genus of insects, with
5 species. In 1810, Latreille declared scorpions to be a zoological Order in their own right, as part of
the class Arachnida. Since Latreille, the study of scorpions has improved considerably, although
there remains some disagreement as to whether or not scorpions really are true members of the
Arachnida. Whilst some maintain that they are an ancestral stem group of the Arachnida, others
suggest they are the only living relatives of a distinct Class called the Merostomata. For the time
being, however, it is usual to consider scorpions as a distinct group "Scorpiones" within the Arachnida.
The genus Euscorpius - the yellow-tailed scorpions
The taxonomy of the genus is rather confused. General consensus is that there are five species and
numerous subspecies. These are primarily European, though some are found on the Mediterranean
coast of North Africa.
Euscorpius flavicaudis
Euscorpius flavicaudis is a small species, only about 4 centimetres in length. The body, including
the pedipalps (claws) and tail, is black, but the legs and the telson (sting) are a pallid yellow (Plate
15). The distinctive pattern of trichobothria on the pedipalp chela quickly distinguishes this species
from others (which are very similar) in the genus (see Vachon 1962, 1975).
Euscorpius flavicaudis is nocturnal (Cloudsley-Thompson 1968. and personal observations). As
dusk falls the species moves to the edge of the crevice in which it resides and remains visible
throughout the night until dawn when it retreats into the crevice again (Benton 1992). It lives for
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Essex Naturalist (New Series) 18 (2001)