Question

Antennary glands of crustacean are meant for-
A. Excretion
B. Respiration
C. Digestion
D. Circulation

Answer 1

Hint:-These glands are opaque-white structures of pea seed size, enclosed in each 2nd antenna's coxa. They also had an end sac as well as a convoluted duct that can develop into a bladder and act as osmoregulatory organs before opening to the outside.

Complete step-by-step solution:-
Option A is correct. The excretory system of the crustacean (Palaemon) consists of a pair of antenary or green glands, a pair of lateral ducts and an unpaired sac coxa of the renal or nephro peritoneal sac enclosing each antenna with the antennary gland. Fluid is drained from the blood into an end sac in the antennal gland of the freshwater crayfish (Astacus) and passes via a tubular maze, where ions are reabsorbed, to create a hypotonic urine that passes to the bladder through a renal tubule.
Option B is incorrect. Crustaceans use the same respiratory system as fish and breathe oxygen through the gills because they are marine creatures. Gills, a respiratory organ of the crustacean, are somewhat similar to the lungs in the way they act. Tiny oxygen molecules are drawn into the bloodstream when they move through the surface of the gill or lung.
Option C is incorrect. Food is eaten through the mouth of crustaceans and transferred through the digestive tract. Depending on the animal, there may be a structure called the gastric mill at the start of the digestive tract that is used to grind down harder pieces of food.
Option D is incorrect. Crustaceans have an open circulatory system, meaning that all their blood is not stored in tubes, but blood is drawn through holes called ostia into the heart, then pumped out again to circulate through the tissues and return to the heart again.
So, the correct answer is Option A.

Note:- Antennal or maxillary glands, depending on whether these open at the base of the maxillary glands or at the base of the antennae. When the tubule adjacent to the excretory pore is green, the gland is called a green gland.