Question

What is true about Nereis, Scorpion, Cockroach and Silverfish?
A. All possess’ dorsal heart.
B. None is aquatic.
C. They belong to the same phylum.
D. They have joined paired appendages.

Answer 1

Hint: All these animals Neries, scorpion, cockroach and silverfish are invertebrate animals. These animals lack notochord throughout life. Pharyngeal gills-slits are absent in invertebrates, they also lack post- claudia tail.

Complete answer:
Nereis is an organism that comes under the genus of polychaete worms belonging to the phylum Annelida. While the organisms like scorpion, cockroach and silverfish, comes under the phylum Arthropoda which shows the common characteristic of jointed paired appendages. Among them, Neries is only aquatic. The only common characteristic among these all organisms is that they all have a dorsal heart.
Option A is correct because all these Neries, Scorpion, Cockroach and silverfish belong to invertebrates and possess a dorsal heart in their body; it is a type of long elongated tube like structure present in the mid dorsal line of the thorax.
Option B is incorrect because among them scorpion, cockroach, silverfish and Neries, Nereis is an aquatic annelid.
Option C is also an incorrect option because Scorpions, silverfish and cockroach come under the same phylum i.s. arthropoda but among them Nereis belongs to the phylum annelids. So the option C is wrong.
Option D is also incorrect because among them insects belong to the phylum arthropoda having jointed appendages but Nereis doesn't have so the option D is wrong.

Hence, the correct answer is option (A).

Note: Some of the characteristics of non chordates are that they solid, ventral and double central nervous system. Gills are also absent in non chordates. The gut in non chordates is present at the dorsal side of nerve cord. Heart is also present at the dorsal side of the nerve cord.