Question

Leech , Nereis , Scolopendra , prawn and scorpion all have segmented body organization, but still cannot be classified under one group. Which of these following is the correct basis for the classification of these organisms into different groups.
A. Leech and Nereis belong to phylum Annelida because they have metamerically segmented body
B. Scolopendra , prawns and scorpion belong to phylum Arthropoda because they have jointed appendages
C. Leech Nereis and scolopendra belong to phylum Annelida because they posses closed blood vascular system
D. Both A and B

Answer 1

Arthropoda, any member of the phylum Arthropoda, the animal kingdom 's largest phylum, containing common forms such as lobsters, crabs, spiders, mites, flies, centipedes, and millipedes. Annelids are known as a coelomate worm with a thin flexible cuticle around the body, triploblastic, bilaterally symmetrical, metamerically segmented.

Complete Answer:
Phylum Annelida:vMost of them are aquatic; some terrestrial, burrowing or tubicolous, sedentary or free-living, some commensal and parasitic, marine or freshwater.
- The body is segmented metamerically into a number of divisions; transverse grooves externally and septa internally; each division is referred to as a section, metamere or somite.
- The organisation of the body is an organ-grade system.
- When present, appendices are joined.
- Regeneration is prevalent.
- In others, asexual reproduction occurs.
- Approximately 8,700 recognised species of Annelida, mostly due to the presence and absence of parapodia, setae, metameres, and other morphological features, are classified into four major groups.

Phylum Arthropoda: This phylum comprises many broad classes and includes the Insecta class, which represents a substantial portion of the world's animal species. In any habitat, they have the capacity to thrive.
The features of Arthropoda are discussed below:
- The body is triploblastic, segmented and symmetrical in a bilateral way.
- They show the extent of structure of the organ system.
- There is a division of the body into the head, thorax , and abdomen.
- Their bodies have jointed appendages that assist with locomotion.
- Phylum Annelida contains Leech and Nereis because they have a metamerically segmented body, i.e. the body is internally divided by septa into several parts. Phylum Arthropoda belongs to Scolopendra, prawn, and scorpion since the body portion of these species typically carries paired lateral and joint legs or appendages.

The correct Answer is option (D) Both A and B.

Note: The arthropods were thought to have formed from the same root as the annelids. It is assumed that the three arthropod lineages have developed independently from a common ancestor. 80 percent of animal species are classified in Phylum arthropoda. Over the years, these animals have developed some adaptive features to survive the evolving climatic environments and form the animal kingdom's largest phylum.