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MAMMAL NAMES | Micro-Monsters Part I:

The Venomous, Wicked & Cruel Names for Ireland's Pygmy Shrews

Surprisingly, the tiny pygmy shrew has many negative names associated with it
‘In 1607 the English naturalist Edward Topsell wrote one of the first known descriptions of the Eurasian common shrew, and it was not flattering. “It is a ravening beast,” he stated, “feigning itself gentle and tame, but being touched it biteth deep, and poisoneth deadly. It beareth a cruel mind, desiring to hurt anything, neither is there any creature it loveth.”’

Thus begins the chapter on shrews in The Encyclopedia of Mammals edited by David W. Macdonald, and across the centuries these words have lost none of their venom. It is a curious thing that so small a creature as a shrew should evoke such powerful feelings of hostility, and it seems especially egregious when we consider the particularly diminutive dimensions of the only species present in Ireland – the pygmy shrew.

Having opened with lines of such seething disdain directed towards the shrew, it seems only appropriate to begin our exploration with the word ‘shrew’ itself. The negative meanings attached to this name go back to at least the 13th century when it was used to refer to a ‘spiteful person’, whether male or female, thought to be due to the belief that the shrew has a venomous bite. But though a number of shrew species are indeed venomous, and this includes the Eurasian water shrew (Neomys fodiens) that inhabits Britain, neither the common shrew of that land or the pygmy shrew of Ireland has a venomous bite.

In any case, by the late 14th century the use of ‘shrew’ as a pejorative term had morphed into one directed solely at females, meaning a ‘peevish, malignant, clamorous, spiteful, vexatious, turbulent woman.’ Early in the life of the English language, then, ‘shrew’ had come to have some extremely negative meanings, and this is also true of other words derived from it, such as ‘shrewd’. The meaning of this word was originally far more negative than it is today, in the early fourteenth century meaning ‘wicked’ or ‘evil’, deriving from shrewe, meaning ‘wicked man’.

But, of course, these are alternative meanings of the word ‘shrew’, and when we look at the actual origins of the word these are not loaded with such negativity and are far more evocative of the shrew’s form.

It is thought that ‘shrew’ may ultimately derive from the Proto-Indo-European root skreu, meaning ‘to cut; cutting tool’ (the word ‘shred’ may be derived from it also), which is possibly a reference to its narrow, pointed snout. From this ancient root, then, there arose the Old English word screawa, meaning ‘shrew-mouse’. Indeed, an alternative name for the shrew in Old English, scirfemus, also has somewhat mousey connections, or at least rodenty ones, coming from the word sceorfan, meaning ‘to gnaw’, a behaviour from which the name of the order Rodentia is also derived, coming from the Latin verb for ‘to gnaw’, rodere.

It is easy to see from this picture why one of the Old English names for ‘shrew’ was possibly derived from its long snout

And the shrew’s appellative connections to the mouse do not stop there, as one of its Irish names is luch fhéir, meaning ‘grass mouse’. In fact, it shares this name with a true mouse in Ireland, the wood mouse, which is also the ‘grass mouse’ in Irish, as we have seen previously.

However, although the ‘grass’ part of this Irish name for the pygmy shrew is quite suitable, this little mammal often being found in grassland, the mouse part really is not when we consider the truth of its evolutionary relationships. Although the pygmy shrews and mice in Ireland inhabit the same micro-worlds and have a somewhat similar form, they are actually not that closely related, belonging to two different superfamilies of the placental mammals. Incredibly, the tiny pygmy shrews scurrying through Irish lands that make blades of grass look as tall as trees are closer relatives of leviathans swimming through Ireland’s seas such as the blue whale, while Ireland’s mice, in turn, are more closely related to the island’s humans than the pygmy shrew.

That the pygmy shrew is a closer relative of the blue whale than the mouse is simply mind-blowing, and it becomes more so the deeper we look at just how small it is.

At birth, pygmy shrews weigh just a quarter of a gram (0.25g). To put that in context, baby pygmy shrews weigh 10 million times less than baby blue whales, which emerge into the world tipping the scales at a monstrous two-and-a-half tonnes. Unsurprisingly, then, while the blue whale is the largest mammal alive and simply the largest animal ever to inhabit the Earth, the pygmy shrew is one of the smallest, at certain times of the year adults weighing as little as three grams, which is only a little more than the weight of a US or Euro one cent coin!

It's clear when compared to its relative the common shrew and a bottle cap why the pygmy shrew deserves its name

This weight of three grams is reached by immature adults in the spring, having lost weight over the winter, and how the pygmy shrews do this is one of the most interesting things about them. Being unable to hibernate like their relatives the hedgehogs, shrews take drastic measures to reduce the amount of energy they need by not just losing weight in terms of the loss of fat or muscle, but through actually shrinking their skeletons, skulls, and even brains, only for these to be regrown (only partially in the case of the skull) in spring – a process known as ‘Dehnel’s phenomenon’, after the scientist who first recognised it.

In spring, then, it seems Ireland’s pygmy shrews are at their pygmiest, and overall it is very easy to see where this little mammal gets its scientific name, Sorex minutus coming from Latin and simply meaning ‘tiny shrew’. The tiny size of one of its features is also the source for the pygmy shrew’s more lyrical, but inaccurate, Irish name, dallóg fhraoigh – the ‘blind animal of the heather’. This name may derive from the fact that the eyes of pygmy shrews are quite small, and sometimes even hidden by fur. However, although they rely far more on hearing and smell, they are not blind, even if their eyesight is poor.

The micro-sized proportions of the pygmy shrew, then, are clear and obvious, and it is actually due to these that the shrew engages in behaviour which has attracted some of the disdainful titles we began this post with. For instance, the pygmy shrew is without doubt a ‘ravening beast’, but this is because its tiny size means that it has to eat constantly to survive. Thus, pygmy shrews gobble an amount of food at least equal to their own body weight each day, in Ireland their main prey being beetles, woodlice, and flies, although the fact that earthworms are generally off the menu because they are too big to tackle serves to highlight once more just how small these creatures are.

In fact, pygmy shrews must eat every few hours or they will starve to death, and this need to secure food explains another behaviour which may have led the seventeenth-century naturalist Edward Topsell to claim the shrew has ‘a cruel mind, desiring to hurt anything...’. Securing food means pygmy shrews are very territorial, and so when two run into each other they are extremely aggressive, such encounters nicely captured by Hayden and Harrington: ‘If a pair of shrews meet, there is usually a bout of threats involving short explosive hisses and tail lashing. Sometimes these encounters escalate to physical violence.’

If pygmy shrews are ravening beasts with cruel minds, then, this is because they have to be to survive, their lives lived in such a fever of activity that they rarely last more than 13 months in the wild. And links to this ravenous nature can even be found in the common name of the group they belong to.

There are three subfamilies within the shrew family Soricidae, with pygmy shrews belonging to the Soricinae, AKA the ‘red-toothed shrews’. This name conjures up yet more images of a ravenous, bloodthirsty creature, but it is perhaps not quite as bloody as it sounds. The red colour of the tips of their teeth is actually due to the presence of iron, something which makes them more hard-wearing, although the necessity for this feature is thought to be due to their bloody dispatching and voracious gobbling of invertebrates, many of which have hard shells.

Illustration showing the red teeth of a typical shrew belonging to the subfamily Soricinae

And while we’re on this subject, one of the other major shrew subfamilies is the Crocidurinae, known commonly as the ‘white-toothed shrews’, and it is the arrival of one of their number in Ireland that has in recent years made the lives of many pygmy shrews on the island even more brutish and short. The greater white-toothed shrew (Crocidura russula) is thought to have arrived in Ireland in 2004, possibly having been accidentally introduced with animal fodder from France, and it is now found in many counties in the southern half of the island. The poor pygmy shrew has disappeared from large areas that have been colonised by this invader, which is about twice its size. When the pygmy shrew is compared to this rapacious, land-grabbing interloper, then, it is the latter that could be considered the true micro-monster in Ireland.

And before we leave the white-toothed shrews, there is one more member of theirs that we must mention, as it is also a pygmy shrew – the white-toothed pygmy shrew, AKA the Etruscan shrew (Suncus etruscus), which is found as close to Ireland as France. Just as the greater white-toothed shrew out-competes the pygmy shrew on land in Ireland, so too does its relative the pygmy white-toothed shrew out-compete the Irish pygmy shrew in the record books.

We have already seen that Ireland’s pygmy shrew is one of the smallest mammals on Earth, but it is not the smallest. The Etruscan shrew is one of two species that are lighter than it, the other being the absolutely minuscule bumblebee bat (Craseonycteris thonglongyai) that lives around 10,000 kilometres from Ireland in the limestone caves of southeast Myanmar and western Thailand. Both of these mini-mammals can weigh under two grams, although, with an average weight of 1.8 grams, the Etruscan shrew is the lighter, claiming for itself the title of ‘world’s smallest mammal’.

The absolutely tiny Etruscan shrew, AKA the pygmy white-toothed shrew, which is even smaller than Ireland's pygmy shrew

So, as incredible as it may sound, even a tiny, three-gram pipsqueak like Ireland’s pygmy shrew can seem monstrous when measured against the very smallest mammals on our planet like the Etruscan shrew. And this serves to provide us with yet another surprising perspective on the pygmy shrew, alongside the bloody realities we have encountered about its nature so far. Ultimately, though, we have to acknowledge once more that if the pygmy shrew is a red-toothed, ravening beast with a cruel mind, it is because it has to be, contending as it does with biological imperatives that leave no room for mercy. To put it another way, in order to simply survive, it must be a micro-monster.


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