| 21. | These vertical migrations often occur over a large vertical distances, and are undertaken with the assistance of a swimbladder.
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| 22. | Thus, they perform a daily vertical migration of 15 meters, no small feat a creature only 3 mm long.
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| 23. | Nauplii and copepodids are positively phototactic and exhibit a daily vertical migration, rising during the day and sinking at night.
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| 24. | The swimbladders of deep sea fish are either absent or scarcely operational, and bathypelagic fish do not normally undertake vertical migrations.
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| 25. | Electronic tagging has shown Humboldt squid undergo diel vertical migrations, which bring them closer to the surface from dusk to dawn.
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| 26. | They follow vertical migrations of the zooplankton they feed on to the bottom during daytime and to the surface at night time.
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| 27. | Electronic tagging has shown that they also undergo diel vertical migrations which bring them closer to the surface from dusk to dawn.
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| 28. | This species undergoes vertical migration from 900 500 m depth during the day, rising to 263 102 m depth at night.
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| 29. | Most types of plankton and some types of nekton have exhibited some type of vertical migration, although it is not always diel.
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| 30. | In the North Sea, " P . pileus " makes large daily vertical migrations as do its main copepod prey.
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