Page 110 - General and Inorganic Chemistry for Advanced Secondary Schools Students Book Form Five and Six

Biology for Secondary Schools

(c) Some annelids are used as bait (c) Earthworms can increase soil
in the fishing industry. Examples porosity and aeration which may
of annelids used as bait include cause water loss by seepage from
earthworms and lugworms. the farms.
(d) They are used as source of nutritious
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food for some fish and birds. They Exercise 5.7
are rich in proteins and vitamins. 1. What morphological features
(e) Some annelids are ecological differentiate earthworms from
decomposers; hence, they contribute tapeworms?
to nutrient circulation in the 2. What is the function of chaeta
ecosystems. found in most annelids?

(f) They remove pollutants from the 3. Imagine you are walking around
soil and clean the environment by school farm and you come
transforming organic wastes during across someone who is killing
feeding. earthworms. Educate that person
(g) Faeces and urine of some annelids the importance of earthworms.
have considerable value as manure
and they increase soil fertility. Phylum Arthropoda

(h) They are used as specimens in The term Arthropoda originates from
biological studies. two Greek words, “arthron” meaning
(i) The excretory waste of some joint and “podos” meaning foot.
Literally, arthropods are organisms
annelids which are in the form of with jointed appendages. Arthropods
cast increases sticking together of are the most successful animals on the
soil particles. This in turn increases earth. They are found almost in every
water holding capacity of the soil.
habitat, including marine, freshwater,
and terrestrial habitats. They vary
Disadvantages of annelids widely in their habitats and feeding
(a) Some annelids damage young habits. Examples of arthropods include
roots of the growing plants. prawn, scorpion, tick, beetle, butterfly,
(b) Leeches are harmful to mammals, crab, spider, centipede, millipede and
reptiles and fishes, because they grasshopper, as shown in Figure 5.32.
suck blood from them.

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