How do Anopheles mosquito larvae position themselves in the water?

Anopheles mosquito larvae are known for positioning themselves parallel to the water's surface. This orientation is essential for their survival as it allows them to feed efficiently on organic matter and microorganisms present just beneath the surface. Being parallel enables them to access oxygen more easily; they can quickly reach the surface to breathe, as they possess a long siphon that allows them to take in air while remaining submerged.

In contrast, the other positioning options do not align with the behavior of Anopheles larvae. For instance, a vertical position near the bottom would limit their access to surface oxygen and hinder their feeding. Haphazard positioning across the surface or perpendicular to it would not provide the same efficiency in feeding or access to air. Therefore, the parallel orientation is key to their development and adaptation in aquatic environments.