Woodlice do not produce urine. Instead of excreting urine, woodlice
excrete their nitrogenous waste in the form of ammonia gas. Most animals find ammonia to
be too toxic for excretion and so any ammonia formed is normally converted to urea or uric
acid for excretion.
Woodlice seem to have very high resistance to ammonia and are able to excrete it as a
gas directly through the surface of their exoskeleton. This means that they do not need to
use energy to convert the ammonia to area or uric acid before excretion.
Woodlice along with most other crustaceans have the compound haemocyanin in
their blood. Haemocycanin carries oxygen in the same way that haemoglobin does in mammals.
Haemocycanin contains a copper atom instead of the iron atom found in haemogobin. The
blood is pale blue when it is carrying oxygen and colourless when it is not carrying
Because a woodlouse contains very small amounts of haemocycanin it is not possible to
see these colour changes by direct observation.
An iridovirus can infect woodlice and at advanced stages of infection virus accumulates in
such large numbers that it forms crystallinel structures in the diseased tissues. These
crstalline structures give an intense blue or purple colour to the woodlice.
Individuals infected to this extent will usually die within a short time.
Orange Porcellio scaber
This orange form appears to be rare in
this region. The example here is the only one found in a collection of over 400 from the
same compost heap - it is also the only one, of two, that I have observed over the last 10
years. The red forms of woodlice are genetically determined but their rarity suggests that
this form is not as well adapted to the habitat as the darker gray forms.
Woodlice, like many other animals, eat their faeces. In the case of woodlice this
helps them to reabsorb sufficient copper minerals which have been lost in their faeces.
Bacterial action on the faeces probably changes the copper to a form which is more easily
absorbed into their bodies. Coprophagy is the term used to refer to the eating of faeces.
Drinking through the anus
Woodlice get water with their food. But they can also drink it through their mouth
parts and also by using their uropods. The uropods are tube-like structures on the
posterior (back end) of the animal. When they use them for drinking they press their
uropods close together and touch it against a moist surface. Capillary action pulls the
water up the uropods and into the anus.
Woodlice also seem to be able to absorb water vapour directly through their exoskeleton
surface in regions of high humidity, and in fact if they remain in high humidity regions
for too long they appear to become water logged and then tend to move to areas of lower
Isaac Asimov and Woodlice
When he was a young child, Isaac's mother was startled by the strange expression on
his face and asked him what was wrong. He was unable to reply so she became alarmed by
this apparent affliction. Isaac, in an effort to calm his mother spat out a mouthful of
When asked why he had done such a thing, he replied that he had thought that they would
probably tickle his tongue as they walked about inside his mouth. Apparently they did
tickle - although his mother did not appreciate this turn of scientific curiosity.
You may sometimes see a woodlouse which is two-toned. For example the front half of
the body may be a pinkish colour and the back half may be the "normal" grayish
colour. This occurs because the woodlouse moults its exoskeleton in two sections. It first
moults the back half of its exoskeleton, then a few days later it moults the front half.
The advantage of this two part moult is to help reduce its vulnerability to predation
or desiccation during moulting. Adults moult about every two months.
Sense of smell
Woodlice are able to detect chemical odours by using sensory receptors on either the
ends of the large antennae or on the surface of their antennulae (these are usually an
inner pair of insignificant small antennae) P. scaber seems to be able to detect
litter by smelling the odours released by micro-organisms living on the litter.
In 1995 St. Helena issued a set of
stamps depicting small animals. The 53p stamp shown here, illustrates a Spiky Yellow
Woodlouse. Why is the rest of the world ignoring these fascinating creatures?
Male woodlice infected by Wolbachia bacteria will turn into female
woodlice! The bacteria upset the normal action of the woodlouse male
As the bacteria are passed to the next generation of woodlice in the
cytoplasm of the egg cells this process means that there is a better chance of
Wolbachia survival as all infected offspring will be female and therefore will allow infection of the third generation of woodlice.
If any reader knows of other
interesting facts, stories, poems, recipes etc then please feel free to contact me. Thankyou.