Question

Which of the following matches is correct?
A. Cockroach – Crustacea
B. Pila – Pelecypoda
C. Spider – Arachnida
D. Unio – Gastropoda

Answer 1

Hint:The animals mentioned above are invertebrates. Invertebrates are those animals that have no backbone or bony skeleton. They have a wide variety of sizes ranging from microscopic mites to giant squid with soccer-ball-size eyes. This is one of the largest groups in the animal kingdom, having almost 97 % of all animals in the world.

Complete answer: Cockroach belongs to class Insecta of phylum Arthropoda.
Pila belongs to the Gastropoda class of phylum Mollusca.
Spider belongs to the class Arachnida of phylum Arthropoda.
Unio belongs to the class Pelecypods of phylum Mollusca.
1. Phylum Arthropoda – Characteristics, Features, and Example-
The phylum Arthropoda is the largest phylum of the Animalia kingdom which includes different insects. Over two-thirds of all species on earth are arthropods. It is an invertebrate animal that has an exoskeleton, a segmented body, and paired jointed appendages or legs. The word Arthropoda comes from the Greek word arthron, which means "joint" and pous, meaning "foot" which means these animals have joint legs. So, they are named Arthropoda.
2. Characteristics and features of phylum Arthropoda-
They have an organ-system level of body organization.
They are bilaterally symmetrical and triploblastic.
They are segmented and coelomate animals that mean they have a true body cavity.
The body is covered by an exoskeleton, called chitin.
The body of these animals is divided into three parts – head, thorax, and abdomen.
They have jointed appendages (legs).
These animals use gills, book gills, book lungs, or tracheal systems as their respiratory organs.
The circulatory system is of open type in these animals.
Hemocoel is present in arthropods (for example cockroach).
They have sensory organs like antennae, eyes (compound and simple), statocysts (help in balancing).
Malpighian tubules are the excretory organ.
They are mostly dioecious that means sexes are separated.
Fertilization takes place internally.
They are oviparous (means they produce young by laying eggs)
Development is direct or indirect.

So, the correct answer is option C. Spider – Arachnida.

Note: Some important examples of arthropods with their common names:
Economically important– Apis (Honey bee), Bombyx (Silkworm), Laccifer (Lac insect)
Vectors – Anopheles, Culex, and Aedes (Mosquitoes)
Gregarious pest – Locusta (Locust)
Living fossil – Limulus (King crab)