Question

Which one of the following is not an arachnid?
A. Spider
B. Tick
C. Mite
D. Lice

Answer 1

Hint: Arthropoda are the largest phylum of the animal kingdom and consists of nearly nine lakh species. Arachnida is a class of joint-legged invertebrate animals arthropods.

Complete answer:
Phylum Arthropods possess a segmented body, a hard exoskeleton, and appendages used for feeding, sensory structures, defense and locomotion. Arthropods are divided into four major groups:
i. Insects
ii. Myriapods
iii. Arachnids
iv. Crustaceans

Option A: Class Arachnid is a member of the arthropod group that includes spiders, daddy longlegs, scorpions. Arachnids is a group of organisms having jointed appendages. These are invertebrate animals. They have eight legs and back jaws. The arachnid body is divided into two distinct regions: the cephalothorax, or prosoma, and the abdomen, or opisthosoma. Arachnids have segmented bodies. Spider belongs to this class.

Option B: Tick also belongs to the class arachnid. They are parasitic arachnids. Ticks are external parasites, living by feeding on the blood of mammals, birds, and sometimes reptiles and amphibians. Ticks belong to this class.

Option C: Mite along with ticks constitute the subclass Acari. Mites are very small, ranging from 0.5 to 2.0 mm in length. They have eight legs and a body with little or no segmentation. Mites belong to this class.

Option D: Lice is a wingless insect of the order Phthiraptera. They are not included in the group of Arachnids. Lice is an obligate ectoparasite of humans that causes head lice infestation. They do not belong to the class arachnid.

Therefore, D is the correct option.

Note: It is to be noted that arachnids differ from insects as they possess eight legs while insects have six legs. Also, insects have wings or antennae while arachnids don't.