These are organisms which belong to the animal kingdom. Their cells do not have
cellulose cell walls anf they lack chlorophyll. The word animal comes from the Latin
animare meaning soul - the life giving and vital principle of these
creatures. In general animals are able to move their bodies from one location to another.
This is the largest phylum in the animal kingdom. It includes insects, spiders,
crustaceans, centipedes, millipedes and others. The major feature of arthropods is their
exoskeleton and segmented body with paired appendages for movement. The exoskeleton
provides support and protection. The joints in the exoskeleton consist of thin flexible
sections which are able to flex and bend to allow movement.
The presence of the exoskelton requires moulting of the old exoskelton followed be a
rapid increase in size before the new exoskelton hardens.
Arthrpods have a dorsal heart which pumps the blood into the haemocoel cavity. Blood
may be red, blue, green or colourless depending on the type of oxygen carrying molecule
These are arthropods which include crabs, crayfish, lobsters, barnacles, woodlice,
sandhoppers and others. They are mostly aquatic (live in water) and carry out gas exchange
via gills. They have at least two pairs of antennae (though the 2nd pair may be very small
and difficult to locate), and three pairs of limb-like structures which act as jaws.
These are crustaceans in which the thorax has 8 segments and the abdomen has 6 segments
(occasionally 7). There are usually a pair of limbs on each segment - 8 thoracic limbs and
6 abdominal limbs. The femal genital pores are on the 6th thoracic segment while the males
genital pores are on the 8th thoracic segment.
An order of the class Malacostraca. The body of these organisms is dorso-ventrally
flattened (except in the suborder Phreatoicoidea). Most isopods are marine but a large
number are found in fresh water. Most of the suborder Oniscoidea are terrestrial (land
The first segement of the thorax is fused with the head. The next seven segments of the
thorax each have a pair of legs - these legs are called pereopods. The abdomen has five
pairs of pleopods which are used for swimming (in aquatic species) and/or gas exchange.
Eggs are carried in a pouch which forms from plates which grow from the base of the
Terrestrial isopods which live in damp conditions. This group consists of the Woodlice
or pill bugs.
Oniscidea in which the ventral plate of the thoracic exoskelton extend over the base of
the legs and curves slightly upward (this 'overhang' or extension is called the epimeron).
This group also has uropods which project beyond the telson and are flattened and spear
shaped. They cannot roll into a ball shape (compared with the armadillidium which can roll
into a ball shape)
Porcellionidae which have heads with three lobes on the front, where the outer lobes
are strongly developed and the central lobe is almost triangular in shape.
Has numerous wart like nodules (turbercles) over the entire dorsal surface including
the head. Head and body the same slate gray colour (there is some variation in colour,
particularly after moulting and in older individuals).