Y-organ

anatomy

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July 15, 2026

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The Y-organ is a crucial endocrine gland in crustaceans, similar to the thoracic gland in insects, and is involved in regulating molting and metabolism. Located in the head, this organ secretes ecdysone, a steroid hormone that, after conversion to 20-hydroxyecdysone, initiates the molting process.12

However, the Y-organ's activity is controlled by a neurohormone called molt-inhibiting hormone, produced by the eyestalk complex. This neurohormone inhibits ecdysone secretion, meaning molting is triggered by the withdrawal of this inhibitory signal. The endocrine systems of crustaceans, including the Y-organ, are complex and have evolved independently from those of insects, despite some functional similarities.12

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endocrine system
Class Crustacea
…glands are well known: the Y-organ and the androgenic gland. As in insects, hormones and neurohormones of the crustacean regulate molting, reproduction, osmoregulation, metabolism, and heart rate. In addition, the regulation of colour changes is well developed in crustaceans, whereas only a few insects exhibit hormonally controlled colour changes.
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…glands are well known: the Y-organ and the androgenic gland. As in insects, hormones and neurohormones of the crustacean regulate molting, reproduction, osmoregulation, metabolism, and heart rate. In addition, the regulation of colour changes is well developed in crustaceans, whereas only a few insects exhibit hormonally controlled colour changes.
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hormone
Hormones of crustaceans
…actions exerted upon the so-called Y-organ in the head; this organ so closely resembles the thoracic gland of insects that the two may share a common ancestry. In crustaceans, however, the neurosecretion inhibits secretions from the Y-organ, and the molt is initiated by the withdrawal of the inhibitory hormone (in…
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…actions exerted upon the so-called Y-organ in the head; this organ so closely resembles the thoracic gland of insects that the two may share a common ancestry. In crustaceans, however, the neurosecretion inhibits secretions from the Y-organ, and the molt is initiated by the withdrawal of the inhibitory hormone (in…
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crustacean
Hormones
The Y-organs lie in the maxillary segment of decapods and are the source of molting hormones, or ecdysteroids, which promote molting and interact with molt-inhibiting hormones from the X-organ.
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The Y-organs lie in the maxillary segment of decapods and are the source of molting hormones, or ecdysteroids, which promote molting and interact with molt-inhibiting hormones from the X-organ.
Read More