Question

Which one forms a connecting link between annelida and arthropoda?
A. Peripatus
B. Chaetopterus
C. Limulus
D. Bonellia

Answer 1

Hint: It has a soft, elongated body covered by thin cuticles, is soft and has a velvety texture with segments. It has paired appendages. It possesses the characteristics of both annelids and arthropods.

Complete Answer:
Invertebrates are generally soft-bodied animals that lack a rigid internal skeleton for the attachment of muscles but often possess a hard outer skeleton. More than 90 percent of all living animal species belong to invertebrates.

A) Peripatus belongs to phylum Onychophora. It has jointed paired legs, compound eyes and tracheas like other arthropods but also displays certain annelida characteristics, such as worm-like segmented body, non-chitinous cuticle and segmental nephridia. The body of Peripatus shows certain structures that are similar to annelids and other structures found in arthropods. Therefore, they are regarded as the connecting link between Annelids and Arthropods.

B) Chaetopterus is an annelid commonly known as parchment tube worm. It is a marine, tubicolous, burrowing worm.

C) Limulus is a genus of horseshoe crab belonging to phylum arthropoda.

D) Bonellia is a marine worm belonging to phylum annelida. It exhibits marked dimorphism and size disparity between the sexes, the male is parasitic in the nephridium of the female.

Thus, the correct answer is option A i.e., Peripatus.

Note: The arthropods show similar features with the phylum Annelida. Both arthropods and annelids have segmented bodies, and some members of the annelid have a pair of appendages on each segment. Both groups show similar body design like a tubular, dorsal heart and similar nervous system.