. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. MUTATIONS IN ARTEMIA 231 changes during larval development. We have used Heath's diagrams to determine the instar of immature shrimps. The morphology of the adult has been described by Weisz (1947) and Lochhead (1950). The adult body consists of head, 11 thoracic segments, two genital segments, and 6 abdominal segments (Weisz, 1947, p. 81). Each of the 11 thoracic somites bears a pair of phyllopodia (Figs. 2 and 5 ). The last abdominal somite is fused to the telson which bears the caudal furca (Fig. 5). The head of Artemia b
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. MUTATIONS IN ARTEMIA 231 changes during larval development. We have used Heath's diagrams to determine the instar of immature shrimps. The morphology of the adult has been described by Weisz (1947) and Lochhead (1950). The adult body consists of head, 11 thoracic segments, two genital segments, and 6 abdominal segments (Weisz, 1947, p. 81). Each of the 11 thoracic somites bears a pair of phyllopodia (Figs. 2 and 5 ). The last abdominal somite is fused to the telson which bears the caudal furca (Fig. 5). The head of Artemia bears a pair of slender antennules and a larger pair of antennae. The antennae show sexual dimorphism, being larger and modified for clasping in the male (Figs. 1, 2 and 5). The median eye consists of three cups, or ocelli. It is red in the first instar and does not gain black pigment until the second (Vaissiere, 1961, p. 29). By the third instar, black pigment is usually present in the rudiments of the lateral com- pound eyes also. The normal compound eye is seen in Figures 7 and 12. The cuticle, which is secreted by the epidermal cells, is not thickened to form a lens. Each ommatidium consists of a cone surrounded by the four crystalline cells which. FIGURE 1. Ventral view of head of normal female (left), normal male (center) and Ctt/+ female with curved antennae (right). secreted it and a proximal rhabdome surrounded by a retinula. The rhabdome lacks the alternating layers of microtubules found in other crustaceans (Eguchi and Waterman, 1965). Each retinula usually contains 5 principal cells and a sixth accessory cell (Debaisieux, 1944, p. 13). The retinular cells contain the photo- stable black-brown pigment which gives the wild-type eye its black color. Each retinular cell is a primary neuron which penetrates the basement membrane and continues as an axon in the fascicular zone of the eyestalk. There are two optic ganglia: the distal lamina ganglionaris and a proximal medul
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
