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Zoology Publications from Victoria University of Wellington—Nos. 63 and 64

Spawning and Development of D. Puniceus

Spawning and Development of D. Puniceus

In the Lyall Bay area D. puniceus spawns from early July to late September. The eggs are deposited on the undersurfaces of large stones and are in close contact, forming flat irregularly shaped egg masses which remain covered with water at low tide. Typically the egg masses are relatively large; one kept in the laboratory measured 13 × 5cm and contained approximately 2,400 eggs. Each egg mass contains sub-groups, each with up to 300 eggs, which differ slightly in colour, ranging from deep purple to pale mauve. The deep purple eggs appear crimson when viewed under the binocular microscope. The variation in colour between sub-groups is mainly a result of the progressive depletion of the yolk page 3supply in the eggs of each sub-group as development advances. This suggests that the eggs of adjacent sub-groups within the same mass are deposited at different times. The pale and small-yolked eggs, which show well-developed eyes, are the most advanced in development and are found mainly in the centre of the egg mass. In some sub-groups, however, the well-developed eggs retain deep purple yolks.

The male collected with the egg mass from Lyall Bay remained with the eggs constantly. It did not eat food offered. It swam backwards and forwards across the eggs, maintaining a constant flow of water over the egg mass. This helped to remove detritus from the egg membranes, and made observation of the embryo through the chorion relatively easy. By comparison the chorion of eggs kept separate from the male soon became covered in foreign particles to such a degree that the embryo and yolk within were very difficult to see.