Question

State the connecting link between Peripatus with Annelida and Arthropoda.

Answer 1

Connective link is also known as missing link and it is an organism which bears common characteristics of two different groups of organisms, for example, Peripatus.

Complete answer:
First of all, you should know the meaning of connecting links. Connecting link is an organism which possess same characters of two different group of organisms or in simple words, they share same characteristics but these organisms are of different groups, for example, Platypus which is connecting link between reptiles and mammals, Peripatus which is connecting link between annelida and arthropoda.
So, peripatus is an arthropod but it displays some characteristics of annelids too. Peripatus is an arthropod as it has joined paired legs, compound eyes and tracheas which all the arthropods possess and they have worm-like segmented body, non-chitinous cuticle and segmental nephridia which are characteristics of annelids. As they have both characteristics, peripatus is a connective link between annelids and arthropods.

Additional information:
Peripatus is a terrestrial animal, it is nocturnal in nature and they are carnivores and predaceous which feed on small invertebrates like snails, worms, etc. They are found living in moist places like in rock, stones, beneath fallen leaves, Their body is caterpillar-like which is soft, elongated, bilaterally symmetrical and the length ranges from 1.4 cm to 15 cm.
Their skin is covered with cuticles which is also characteristic of annelids and their ventral surface is always flesh-coloured. Their digestive system consists of digestive glands and alimentary canal. The body cavity in peripatus is haemocoel which is lined with epithelium.

Note: Peripatus is a connective link between arthropods and annelids since they have characteristics of both annelids and arthropods. As annelids, peripatus have worm-like segmented body, segmental nephridia, etc. and as arthropods, they have jointed pairs legs. Hence, they are the connecting link of both the groups.