Question

Which of the following organisms does not come under Arachnida?
A. Spiders
B. Termites
C. Scorpion
D. Ticks

Answer 1

Hint: Arachnida is one of the 7 classes of the phylum – Arthropoda of the animal kingdom. They are also known as Octopoda because of the characteristic presence of four pairs of walking legs. Arachnida has cephalothorax (A condition where the head and thorax are fused).

Complete answer:
The characteristic features of Arachnida are one pair of Chelicerae, one pair of Pedipalps which is useful in feeding, and four pairs of legs. Antina is absent from the animal of this class. Respiration takes place in these organisms with the help of the Trachea also known as Book Lungs. They undergo direct development and perform excretion through the Coxal gland or Malpighian tubules or both. Examples include:
> Scorpion - Biological name of the scorpion is Palamnaeus. These are viviparous organisms. The end of these organisms is modified into a poisonous sting.
> Ticks and mites- They are peripheral parasites that feed on the blood of mammals, birds, etc.
> Spider – Biological name is Lycosa/Agelena. Spiders are known as the largest order of phylum arachnids. They contain fangs in chelicerae which are used in the injection of Venom.

Therefore, the correct option is (B) Termites.

Note: Termites belong to the class Insecta to the same phylum. Their characteristic feature is the presence of three pairs of legs and one or two pairs of wings. They are also known as Hexapoda. They perform respiration through the Tracheal system. The head consists of one pair of antennae, compound eyes, and mouthparts. The excretion takes place by Malpighian tubules. Termites fall under the subclass Pterygota (Winged insects). The biological name of Termite is Calotermes.