Question

Choose the features that represent phylum Arthropoda:
I. Metameric segmentation
II. Parapodia
III. Jointed appendages
IV. Bilateral symmetry
V. Triploblastic

• A. I and II only
• B. III, IV and V only
• C. II and III only
• D. IV and V only

Answer 1

The correct option is B III, IV and V only

Organisms such as crabs, insects, spiders have jointed appendages and are a part of phylum Arthropoda. They are bilaterally symmetrical as their bodies can be divided in two equal halves through a single plane. They have three germ layers i.e. ectoderm, mesoderm, endoderm and, hence, are called triploblastic. They also have a true coelom as the body cavity is lined by the mesoderm.

Metameric segmentation is a characteristic feature of all annelids and parapodia is a feature of aquatic annelids (Nereis).

Organisms in phylum Platyhelminthes, Aschelminthes and Annelida are bilaterally symmetrical and triploblastic.