Question

Define and describe the following terms:

a.         Gastriliths:

b.         X-organ:

c.         Sinus gland:

d.         Ecdysis:

e.         Y Organ:

Answer 1

a. Gastroliths

A gastrolith, also known as stomach stone or gizzard stone, is a rock held inside a gastrointestinal tract.They are small stones swallowed by some species especially bird, reptile, or fish to aid digestion in the gizzard.They are retained in the muscular gizzard of these species and used to grind food in animals lacking suitable grinding teeth.

b. X-organ

In class crustacea,the X-organ is a neurosecretory organ.It constitutes the major neuroendocrine system along with its associated neurohemal organ,sinus gland.Both an X-organ and a sinus gland are located in each eyestalk, and together they are termed the eyestalk complex.

c.Sinus gland

It is a small glandular mass in the eyestalk of a crustacean having an endocrine function and being in some respects analogous to the neurohypophysis of the vertebrates.The X-organ passes its secretions to the sinus gland, which acts as a release centre into the blood. Hormones liberated from the sinus gland have been shown to influence molting, gonad development, water balance, blood glucose, and the expansion and contraction of pigment cells both in the general body and in the retina of the eye.

d.Ecdysis

Ecdysis is the process of an arthropod by which it moults its exoskeleton. Moulting is necessary as the arthropod exoskeleton is inflexible and so, to grow larger, arthropods must moult.Since the cuticle of these animals typically forms a largely inelastic exoskeleton, it is shed during growth and a new, larger covering is formed.

e.Y-organ:

In Class Crustacea,Two endocrine glands are well known: the Y-organ and the androgenic gland. The steroid ecdysone secreted from the Y-organ stimulates molting. After it is released into the blood, ecdysone is converted to a 20-hydroxyecdysone, which is the active molting hormone.