PANtiS &iVe!" VcAw# 3( WiAfitaw I & 2 
1 
Life All 
Around Us 
a new’ series about the 
Invertebrates, die Earth's most 
bicxliverse creannx's. dun live 
near, on -and in -us 
Fleur Ng weno 
Box 42271. 00100 GPO. Nairobi 
fleur@africaonline.co.ke 
Nematodes 
in soil, in sea, in 
plants, and in you 
Nematodes are everywhere 
perhaps even in your intestines! They 
are in the plants outside, and in tin; 
insects that eat them They are in the 
soil, and the mud ol lakes and seas, 
by the millions and millions 
Nematodes, sometimes called 
Nemata. are a major group of 
invertebrates — animals without 
backbones. There are thousands of 
species, or kinds, ol nematodes. 
Many of them are not well known. 
Nematodes are small. Most ol 
them are too small to see without a 
magnifying glass or microscope. 
Some are several centimetres long, 
but so narrow that they are difficult 
to see A lew nematodes grow to 
several metres in length. 
Nematodes arc worms. The bask 
nematode shape is long arid 
cylindrical. The body comes to a 
point at each end. At the head end 
the nematode has a mouth and some 
st>eeial sense organs. The nematode's 
digestive system runs down the 
middle of its long, i ylindrical body 
Different nematodes have different 
types ol mouths, depending on their 
way of life. 
Nematodes’ outer covering is 
called the cuticle. It is usually lough, 
ami may he smooth or covered with 
bumps and bristles. Most nematodes 
moult their cuticle four times as they 
grow from eggs to adults With each 
moult they go through a stage of 
development. Adult nematodes are 
usually separate males and females. 
Nematodes affect us in different 
ways. Nematodes break down dung 
and organic matter into particles that 
plants can use. Some live in insects 
that eat plants, and thus help to 
control insect pests. Others feed on 
crop plants and cause much damage. 
Some nematodes are parasites in 
people and animals. They are 
unpleasant, and a few have severe 
effects. 
