Page 189 - Biology_F5

Biology for Advanced Level Secondary Schools

Distinctive features of class Insecta jointed sections or plates to allow the
Insects have the following features that body movement. The exoskeleton is
differentiate them from other arthropods: made up of a structural protein known
(a) Their bodies are divided into three as chitin. It is coated with wax, which is
main regions or tagmata, namely the impermeable to water. The exoskeleton
head, thorax, and abdomen. provides attachment for body muscles.
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(b) They have three pairs of walking legs Cockroaches are mostly dark brown or
on the thorax. reddish in colour. A male cockroach has
(c) They usually have one or two pairs of a narrow abdomen, an expanded tergum
wings on the thorax, some members of the last visible segment, and has a pair
may lack wings. of styles at the end of the abdomen, while
(d) They use the tracheal system as their the female cockroach has a wide abdomen
respiratory structure, composed of with a large podical plate used to carry the
spiracles. ootheca, and lacks styles (Figure 3.53 a,
(e) They undergo metamorphosis during b and c).
their development through moulting
process.
(f) They have a pair of compound eyes 3.7.4 Body systems of insects
and simple eyes.
(g) They usually have three pairs of Task 3.14
mouthparts, which are maxillae, Search from library and internet
mandible, and labrum. sources videos and images showing
the structure of a cockroach and
systems of cockroaches including the
Structure of a cockroach respiratory system, circulatory system,
The body of a cockroach is elongated digestive system, reproductive system
and segmented, and divided into a head, and urinogenital system.
thorax, and abdomen. The thorax is
subdivided into three parts or segments; Like other animals, arthropods have various
prothorax, mesothorax and metathorax body systems that enable them to perform
and each segment bears one pair of legs and sustain their life processes. These
including prothoracic legs, mesothoracic
legs and metathoracic legs, respectively. include: respiratory system, circulatory
In most adult insects the thorax also bears system, digestive system, nervous system,
two pairs of wings. The body is covered reproductive system and excretory system.
by a rigid exoskeletons (cuticle) secreted In this text, only digestive and reproductive
by the epidermal layer. This occurs in systems will be dealt with.

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