Question

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

Answer 1

Hint: All the given animals are invertebrates. Invertebrates lack of notochord throughout life. The pharyngeal gill-slits are also absent and the post caudal tail is also absent in invertebrates.

Complete step by step answer: Nereis belongs to phylum annelida. Annelids may be aquatic or terrestrial. In aquatic habitat, they may be marine or freshwater. Nereis is an exclusively marine animal. Annelids are also called segmented worms. They are metamerically segmented animals having a bilateral symmetry. Nereis possesses locomotory appendages which are flattened, fleshy, laterally projected called parapodia. Blood vascular system is close type.
Scorpion belongs to the phylum Arthropoda and class Arachnida. Arthropods have jointed appendages. The body of a scorpion is divisible into cephalothorax and abdomen. Simple eyes are situated on cephalothorax and possess six pairs of appendages. Six pairs of appendages consist of one pair of chelicerae, one pair of pedipalpi and four pairs of legs. It is a viviparous animal. Viviparous refers to the hatching of eggs within the female body and they show direct development. The excretory organs in scorpions are malpighian tubules or coxal glands.
Cockroach and Silverfish also belong to the phylum Arthropoda and class Insecta. Class Insecta is also known as Hexapoda which consists of the largest number of species. The body of organisms belonging to this class is divisible into the head, thorax and abdomen. Insects are exclusively terrestrial animals.
So from the given organisms all are invertebrate or non-chordates and they possess dorsal heart.
Hence, the correct answer is option A.

Note: Few characteristics of non-chordates are; they have a ventral, solid and double central nervous system. Gill slits are absent, and if the heart is present, then it is on the dorsal side. The gut is present on the dorsal side to the nerve cord.