As the daily tides retreat, they often leave behind twisted bits of seaweed drying in the sun in long rows called strandlines. Beachgoers shove the weeds aside in order to spread their blankets on the warm sand. Closer examination of these remnants reveal a number of different kinds of seaweeds.

On land we have grasses, weeds, ivies, shrubs and trees. These are familiar plants that we see every day with their stems, leaves and roots. Below the ocean surface there are many other plants. We usually do not see them until they have broken free from their growing sites. Seaweeds, or algae, being plants that live in the ocean, must have a way to keep in their growing area and still be exposed to sunlight.

At the bottom of each seaweed is a structure called a HOLDFAST. It looks like a root, but each part has a sticky disc at the end which cements the weed to a rock or shell and holds it in place. Unlike roots, the holdfast does not need to absorb water, since the seaweed is completely surrounded by water.

The plant needs sunlight in order to live. The leaf of a seaweed is called a BLADE. In large seaweeds such as kelp, the blade is supported by a thick structure called a STIPE. It looks like a stem, but acts as a shock absorber to protect from strong currents and waves.

On our beaches you can find examples of the three colors of seaweeds: green, red and brown. Bright green sea lettuce often floats ashore. It is soft and delicate as it drifts in. Some people actually eat it. Red seaweeds, such as Irish moss, often have many small branches reaching out. Then there are the brown seaweeds. One of the most recognizable browns is rockweed.

Often along the branching blades are swollen air bladders. These structures help the plant reach upward toward sunlight. As children, we often ran along the beach to jump on the bladders to make them pop. How sad… Occasionally we can find kelp, another brown seaweed, whose blades can grow up to ten feet long.

Seaweeds have an unusual way to protect themselves when the tide retreats and they are left attached to shells or rocks near shore. In order to not dry up and die in the sun, the algae ooze out mucus to cover the exposed parts. If you step on a seaweed covered rock you may suddenly find yourself falling. Slippery stuff!

So, there are our ocean plant companions. Small crabs, snails, and fish swim among them for protection or for food. Seahorses hold onto the stipes to protect themselves from harsh currents. Check out our seaweeds on your next beach trip. Good luck. Read more