The fronds of giant kelp are kept at or near the sea surface via gas-filled floats.

References

"Gas-filled floats keep [kelp] fronds at or near the sea surface." (Koehl 1977:1067)

Journal article
Mechanical adaptations of a giant kelpKoehl, M. A. R. ; Wainwright, S. A.

No link available.

Living System/s

Organism
Bull Kelp.Durvillaea potatorumSpecies