. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 32 FIGURE 8. Growth patterns of two pseudocolonial hydras (Ai, A2) and a typical colonial hydroid Cordylophora (B). In each of the patterns the ordinate represents days. further observation that no part of the "colony" lacking a hypostome was ever detached from the parent mass distinguishes this aberrancy from the stolonizing growth modification described by Haynes, Burnett and Deutschman, 1964. Therefore, although the pseudocolonial hydra was able to retain its asexual reproductive products temporarily, it still m
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 32 FIGURE 8. Growth patterns of two pseudocolonial hydras (Ai, A2) and a typical colonial hydroid Cordylophora (B). In each of the patterns the ordinate represents days. further observation that no part of the "colony" lacking a hypostome was ever detached from the parent mass distinguishes this aberrancy from the stolonizing growth modification described by Haynes, Burnett and Deutschman, 1964. Therefore, although the pseudocolonial hydra was able to retain its asexual reproductive products temporarily, it still maintained the capacity for separation. In this respect it differs from the majority of colonial Cnidarians (Hyman, 1940). The second difference exhibited in the growth pattern of pseudocolonial or- ganisms was an absence of the spatial regularity in the development of individuals witnessed in the Cordylophora colony (see also Fulton, 1961, 1963). This irregu- larity was most apparent in the formation of hypostomes. Regeneration experi- ments by many workers have indicated that, with the exception of the peduncle and basal disc, the entire body column of a hydra normally possesses the capacity for hypostome differentiation. Despite this potential, hypostome formation is normally restricted to the distal end of the animal and to the budding region, an area nearly 60% of the length of the body column removed from the existing oral hypostome. Pseudocolonial hydra developed hypostomes either singly or in clusters at nearly any point along the body column. The proximity of another hypostome appeared to have no effect on the subsequent development of additional hypostomal regions. This type of growth is markedly different from that typically exhibited in the hydra. Figure 9 compares hypostome positions along the column in 24 randomly selected, budding pseudocolonial and normal H. viridis. Each hydra selected was measured linearly and the position of each hypostome marked on graph pape
Size: 1343px × 1861px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
