. Bulletin. Science; Natural history; Natural history. 1971 Al<( I K ( OI''ODS 2't 100 Luclcutla pseudopolarit Luclcutla polarl» I I Luclcutla anomola. 1000 1000- 1500 1500 1500- 2000 2000 2000- 3000 3000 below 3000 Depth i n meter Figure 5 — Percentages of relative abundance and number of specimens of the arctic species of Lucicutia at different depths. intermediate between herbivorous and omnivorous forms, would permit these species to feed on aggre- gates of organic matter and detritus, which range in size from about 1^ to several mm, and on small arganisms of the nannoplankton. The a
. Bulletin. Science; Natural history; Natural history. 1971 Al<( I K ( OI''ODS 2't 100 Luclcutla pseudopolarit Luclcutla polarl» I I Luclcutla anomola. 1000 1000- 1500 1500 1500- 2000 2000 2000- 3000 3000 below 3000 Depth i n meter Figure 5 — Percentages of relative abundance and number of specimens of the arctic species of Lucicutia at different depths. intermediate between herbivorous and omnivorous forms, would permit these species to feed on aggre- gates of organic matter and detritus, which range in size from about 1^ to several mm, and on small arganisms of the nannoplankton. The absence of morphological differences in the structure of the jral appendages (especially between L. pseitdo- fi oolaris and L. polaris) suggests that the above it species are feeding on the same or on a very similar f food supply. Related species can avoid or reduce competition or food by distributing themselves at different depths. Marshall (1954; 1963) discussed the vertical distribution of related species of fishes ( Vinciguerria ;pp; Cyclothone spp: Stomias spp;) and gave exam- Dies of vertical exclusion. Other examples of sharp stratification of related species of pelagic orga- nisms were given by Banse (1964). In general, this behavior might permit a reduction of competition for food and a better utilization of the ecosystem. It is likely that the vertical distribution and stratification of the Arctic species of Lucicutia are the outcome of the interactions of all environ- mental factors through time — physical factors such as pressure, chemical, and more likely biologi- cal factors — tending to a better utilization of the food niches with consequent reduction of interspe- cific competition and better possibilities of survival. ACKNOWLEDGMENTS The author is indebted to Dr. John L. Mohr and Mr. Stephen Geiger (Allan Hancock Foundation). Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - c
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