Journal of the Marine Biological Association of the United Kingdom

Research Article

On the biology of Calanus finmarchicus. VII. Factors affecting egg production

S. M. Marshalla1 and A. P. Orra1

a1 The Marine Station, Millport


Comparatively little is known about the factors affecting egg-laying in Calanus. Deductions from work in the field have been made by Nicholls (1933a, b) and Marshall, Nicholls & Orr (1934), and experimental work in the laboratory has been done by Raymont & Gross (1942).

Emgg-Laying In Calanus

The anatomy of the reproductive system has been described in detail by Lowe (1935). In the female there is a pair of diverticula extending from the proximal end of the oviduct into the head region, and into this the developing eggs pass. Each diverticulum has a dorsal and a ventral channel, and the eggs pass from the dorsal into the ventral channel and then into the oviduct proper. The oviduct rises from the forward end of the ovary and crosses the body laterally and ventrally so that a short part of it can be clearly seen.