Polyclad 
Life 
Around 
Invertebrates, ihe Earth's most 
biodiversc creatures, that live- 
near, on - and in - us 
Fleur Ng’weno 
Box 42271. 00100 GPO . Nairobi 
FLATWORMS 
Platyhelminthes 
simple animals that wriggle 
inside us 
The first arriclc m this sene*. Corals 
and Jellyfish: Builders and Stingers, 
was published in the EASIIS Bn/ltti a 
volume 30 number 1 
Parasitic worms arc ugly, lazy and 
disgusting, right/ Well. Ralph 
Buchsbaum. in his wonderful book. 
Animal* Without Bjtkbmttt, looks at 
parasitic animals from a different 
point of view: 
"Living at the expense of one's 
neighbour is an old habit among 
animals." he explains. Almost every 
animal provides food and lodging lor 
some unwelcome guests - parasites. 
Most parasites arc themselves hosts 
to still smaller parasites. In facr. 
there arc probably more parasites 
than hosts! 
Most people sec patasites as 
somehow 'immoral* or at least less 
respectable' than their free-living 
relatives." writes Buchsbaum. But 
since there arc more parasites than 
tree-living individuals, a parasitic 
existence must be considered a 
normal w-ay of life." 
To survive, a parasite must do as little 
harm as possible to its host, lie adds. 
Who can say that a parasite is less 
considerate* than a carnivore, which 
kills irs victim outright' 
Elat worms live near us - too near' 
Many of them live inside our bodies 
Flatsvorms include the blood flukes 
that cause bilharzia and the 
tapeworms and hydatid cysts 
Flat w orms arc not all parasites. 
Polyrlads are some of the most 
beautiful creatures of the sea. like 
brightly coloured ribbons Other 
flatworms live independent lives in 
fresh nr salt water and in damp places 
on land 
