write the distinguishing characters of phylum Annelida and classify it up to classes with characters and examples of each class. 3+9=12
Answers
Characteristics of Annelida
The characteristics of the organisms present in the Phylum Annelida are as follows:
The Annelids are coelomate and triploblastic.
They exhibit organ system level organization.
Their body is segmented.
They respire through their body surface.
Nephridia are the excretory organs.
They have a well-developed circulatory and digestive system.
Their body contains haemoglobin, which gives them a red colour.
Regeneration is a very common characteristic of the Annelids.
Setae help them in movement.
Most of the Annelids are hermaphrodite, i.e., male and female organs are present in the same body. They reproduce both sexually and asexually. The others reproduce sexually.
Eg., Earthworms, and leeches
Classification of Annelida
Following are the different classification of Annelida:
Polychaeta
Oligochaeta
Hirudinea
Archiannelida
Polychaeta
The body is elongated and divided into segments.
They are found in the marine environment.
These are true coelomates, bilaterally symmetrical worms.
They excrete through metanephridia and protonephridia.
Fertilization is external.
They have a well-developed nervous system.
The circulatory system is closed type.
They are hermaphrodites.
They might possess fin-like appendages called parapodia.
The organisms belonging to this group lack clitellum and are dioecious.
Eg., Nereis, Syllis