Differentiate between Protochordata and Arthropoda..?
Answers
Protochordate and Vertebrate fall under the classification of 'Chordates'.
Chordates are known to have a notochord (either at a certain stage of life or throughout the lifespan).
Protochordates are the animals having a notochord at some stage or throughout the life. They have no vertebral column (i.e. an evolved notochord). They are further divided into two:
Urochordate
Cephalochordate
Urochodates have a notochord during their larval stage. However, they loose it during adulthood (due to metamorphosis). As they do not have a vetebral column and show the presence of notochord at a certain stage of life, they are included under protochordates.
Cephalochordates have a notochord throughout their lifespan. Therefore, known to be under protochordates.
Vertebrates are the animals possessing a well-developed notocord i.e. Vertebral Column. The question is why are they included under chordates if they don't have a notochord? The obvious answer can be that Vertebral Column is an evolved notochord by itself. But a more accurate answer would be that Vertebrates show the presence of notochord in their body during embryonic stage (as an embryo in mother's womb) which further develops into vertebral column.
Answer:
arthropoda had a bilaterally symmetrical and segmented.arthopoda has jointed legs.protochordata are bilaterally symmetrical and triploblastic and have a coelom.