One adaptation of seaweed is that some types of seaweed, such as kelp, have holdfasts instead of roots. Holdfasts grab on to a substrate, such as a rock, and keep the seaweed from washing away during storms. Seaweed also have pnuemocysts, or gas bladders, that keep the fronds afloat.

Seaweed, any of the red, green, or brown marine algae that grows along seashores. Seaweeds are generally anchored to the sea bottom or other solid structures by rootlike ‘holdfasts,’ which perform the sole function of attachment and do not extract nutrients as do the roots of higher plants.

Sea Grass Adaptations for Submergence. Many species live continuously submerged to depths of 20 meters; Adaptations for continuous submergence; Absorb nutrients with leaves as well as roots; Needs of all tissues met by diffussion; Transpiration is unneccessary

Seaweed, or macroalgae, refers to thousands of species of macroscopic, multicellular, marine algae. The term includes some types of Rhodophyta (red), Phaeophyta (brown) and Chlorophyta (green) macroalgae.

Seaweeds, or marine algae, have developed several adaptations to survive in the pelagic ocean biome: 1. Buoyancy: Some seaweeds have air bladders that help them float, allowing them to stay near the surface of the water where sunlight is abundant for photosynthesis.