Organisms in this phylum have jointed appendages and an exoskeleton made of chitin. There are 5 classes in this phylum: Insecta, Crustecea, Arachnida, Diplopoda, and Chilopoda.
The following are the features of Class Insect:
1. Insects have a head, thorax, and abdomen.
2. They have one pair of antennae.
3. They have three pairs of jointed legs.
4. Most adult insects have wings.
Figure 4.1: Dissection of Earthworm
Many insects can be caught in a eld using a sweep net.
Live insects can be kept in a clear bottle and fed grass clippings. Dead insects can be preserved for a few months by placing them in methylated spirits.
Seal in an airtight container until the insect su ocates.
First remove wings, antenae, and legs of the insect. Then cut down the sides of the insect to open the body cavity and observe the digestion and reproductive systems.
The following are the features of Class Crustacea:
1. Crustacea have bi-forked appendages.
2. They have 2 pairs of antennae.
Figure 4.2: Crabs are an example of Class Crustacea
Fresh water crabs, prawns, and shrimp can be found in most rivers, lakes, dams and swamps. Otherwise, they can be purchased in many markets.
Crustacea can be preserved in methylated spirits. Crustacea can also be dried for preservation purposes.
Crustesea can be killed by being left in an airtight container or boiled in water.
For crabs, turn it so that its abdomen is facing up. Wedge a knife under the triangular abdomen and twist, so that the abdomen opens. Examine the internal organs.
The following are the features of Class Arachnida:
1. Arachnids have four pairs of jointed legs.
2. Arachnids have a cephalothorax (head and thorax) and abdomen.
Figure 4.3: Spiders are an example of Class Arachnida.
Spiders can be found in almost any environment. Scorpions can be found in dark, dry and cool areas, usually at night.
Arachnida can be dried or preserved in methylated spirits.
To kill Archnida, place them in an airtight container for a few days or use insecticide.
The following are the features of Class Chilopoda:
1. Chilopoda have long bodies consisting of many segments.
2. Each segment contains a pair of legs.
Figure 4.4: A centipede
Centipedes can be found under rocks, in tree bark, and in leaf litter.
Chilopoda can be dried or preserved in methylated spirits.
To kill Chilopoda, place them in an airtight container for a few days or use insecticide.
The following are the features of Class Diplopoda:
1. Diplopoda have long bodies consisting of many segments.
2. Each segment contains 2 pair of legs.
Milipedes can be found under rocks, in tree bark, and in leaf litter.
Diplopoda can be dried or preserved in methylated spirits.
To kill Diplopoda, place them in an airtight container for a few days or use insecticide.
Figure 4.5: Class Diplopoda contains organisms like millipedes.
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