Write down eight characteristic features of the phylum Annelida and also give its two examples.
Answers
Characteristic features of phylum Annelida :
(i) They may be aquatic (marine and fresh water) or terrestrial.
(ii) They are the free-living animals but some are parasitic.
(iii) They exhibit organ-system level of organisation and bilateral symmetry.
(iv) They are triploblastic, metamerically segmented and coelomate animals.
(v) They possess circular and longitudinal muscles which help in locomotion.
(vi) Nephridia help in osmoregulation and excretion.
(vii) Nervous system consists of paired ganglia connected by lateral nerves to a double ventral nerve cord.
(viii) A closed circulatory system is present.
Examples :
(i) Pheretima - Earthworm
(ii) Hirudinaria - Blood sucking leech
Hope this helps...:)
They have a long and segmented body.
Annelids are bilaterally symmetrical.
They are triploblastic.
Also, they exhibit organ system grade of organisation, showing organ differentiation.
The body is covered with a thin cuticle.
They are coelomate. A body cavity or coelom is present.
Annelids live in moist environments, moist soil, freshwater and marine water.
They have parapodia and chitinous setae, used for locomotion.
Their body appears red due to the presence of haemoglobin.
Excretory and nervous systems are present.
The digestive system is complete and developed.
Respiration happens through the general body surface.
These invertebrates have a true closed circulatory system.
Sexes may be separate or united, wherein they are called hermaphrodites.
Fertilization can be internal or external.