Krill move primarily by swimming, specifically through a combination of swimming and vertical migration. They don't simply drift.
Here's a breakdown of their movement:
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Swimming: Krill use their pleopods (swimming legs) located on their abdomen to propel themselves through the water. These legs beat rhythmically, allowing them to move forward, backward, and maneuver in the water column.
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Vertical Migration: This is a key aspect of krill movement. They undertake daily vertical migrations, moving to deeper waters during the day and ascending towards the surface at night to feed on phytoplankton. This vertical movement is achieved through active swimming. Recent research highlights the importance of this migration:
- Krill actively modify ocean currents through their vertical movement.
- This migration helps mix nutrient-rich water from the depths with nutrient-poor surface water.
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Swarming Behavior: Krill often form large swarms, which can influence their movement patterns. The collective movement of the swarm can be more efficient than individual movement, allowing them to navigate and exploit food resources more effectively.
In summary, krill exhibit a dynamic movement pattern involving both directed swimming and large-scale vertical migration that significantly contributes to ocean mixing. They are active swimmers and not passive drifters.
