644 



THE BIOLOGY OF MARINE ANIMALS 



values. Changes also occur during the moulting cycle in blood-phosphate 

 levels, which are highest immediately preceding a moult and lowest follow- 

 ing it (Homarus). Phosphates are removed from the skeleton prior to 

 moulting, and stored as spherules of calcium phosphate in cells of the 

 hepatopancreas. Following the moult these phosphate reserves are mobil- 

 ized for hardening the new skeleton (spiny lobster, Panulirus) (53a, 57, 66, 

 72, 111, 116, 127, 128a, 128/?). 



Hormonal Control of Moulting. Moulting in crustaceans is under 

 hormonal control, and both moult-accelerating and moult-inhibiting hor- 

 mones are involved. A moult-inhibiting hormone is produced by special 

 neurosecretory organs, notably the x-organ in the eye-stalk of decapods. 

 From the x-organ the hormone is transferred to the sinus gland for storage 



Old 

 cuticle 



New 

 cuticle 



Gastrolith 



Chitinofienous 

 epithelium 



Outer 

 stomac 



Weill 



Fig. 15.3. Diagrammatic Section through the Stomach Wall of a Moult- 

 ing Lobster Homarus, Cutting the Gastrolith. (From Herrick, 1896.) 



and release (Fig. 12.7). Eye-stalk removal accelerates ecdysis and shortens 

 subsequent intermoult periods (Uca, Eriocheir, etc.). The changes induced 

 by eye-stalk ablation resemble closely those observed in the normal pre- 

 moult period, viz. removal of calcium from the cuticle, formation of gastro- 

 liths, increase in oxygen consumption and in water-content of the body 

 (Cambarus, Uca, etc.). Moulting and associated changes are inhibited in 

 eye-stalkless animals by implanting whole eye-stalk or the x-organs of 

 normal donors into their bodies. In some species, removal of the eye-stalks 

 during the moulting season does not initiate proecdysis. Production of a 

 moult-inhibiting hormone by the eye-stalk neurosecretory organs may thus 

 be limited to the non-moulting season. A moult-inhibiting factor may also 

 be produced in sites additional to the eye-stalks [Palaemon, Carcinus) (8, 

 13, 17, 18, 29, 32, 100). 



