http://drreese.wordpress.com/2009/10/19/sea-life-along-the-edge
The next time you are walking along the seashore, take a closer look at the wave-battered coast. The beauty of this extremely brutal ecosystem is enhanced many fold by a growing understanding of how it works.
There is an intriguing collection of animal and plant life that loves along this edge. They are exposed to harsh physical elements: wind, sun and rain when the water recedes at low tide and waves breaking over them at high tide.
The area between the high and low tides is the inter-tidal zone. Suzie and I and our children cherish the times when we get to explore this ecosystem.
Have you ever seen a starfish eat a mussel?
A starfish will drape itself over the mussel, lock its bone-like structures, called ossicles, onto its prey and form a rigid scaffolding. Using its tube feet, the starfish perches between a rock and each shell of the mussel. The starfish contracts its tube feet, prying the shell open. The starfish everts its stomach out of its mouth and squeezes into the narrow gap between the mussel’s shell. The starfish begins to digest the mussel while it sucks it out of the shell.
At low tide amongst the exposed rocks you are likely to see clusters of seaweeds, algae, mussels and goose barnacles. Huddled between the rock crevices are starfish. Hermit crabs scurry between the rocks. The crab carries its house, the shell of a dead snail.
Sea anemones live in tidal pools below mussel beds. As the tide rises, they wait for the waves to wash their prey into their grasp. The tentacles surrounding the anemone’s face are called an oral disk. The mouth is found at the center of its oral disk. A sea anemone has no anus; after digesting a meal, it spits the waste back out of its mouth – including entire shells!
The animal and plant life along the coastline are miraculously adapted to the constant crashing waves. They depend upon the water moving around them to bring oxygen and nutrients, to carry away their wastes, and to transport their offspring to new sites.
Floppy 10-foot-long algae and sea grasses flap and flail in the moving water. They hang onto wet rocks with amazing natural glues.
Sea spiders crawl along the shoreline rocks and rely upon hooks on the end of their feet to prevent them from being swept out to sea. Snails stick to surfaces using their mucus.
The next time a rock is exposed at low tide, notice a distinct pattern in distribution of animals and plants.
The top of the exposed rocks is usually colonized by acorn barnacles and periwinkle snails. Mussels and goose barnacles occupy the next horizontal band. Beneath them are turf algae, and lower still is a zone of larger seaweeds and surf grasses with starfish and sea anemones in tidal pools.
Life at the top of the rock can contend with periodically drying out. Starfish and sea anemones at the bottom, on the other hand, cannot tolerate being sun-baked.
Scientists and engineers have examined a number of animals and plants from the inter-tidal zone; their natural properties are awesome and highly beneficial for humankind. An entire field of biomimetics has blossomed in engineering. The design of human-made materials, devices and structures is inspired by the design of living things.
Non-drip paint mimics the mucus of a snail, which is both a lubricant and a glue. Epoxy glues mimic phenomenal glues from the bottom of barnacles and holdfasts of seaweeds.
The shell of a snail is made of calcium carbonate – an otherwise brittle compound, yet it’s tough because of its exquisite architecture. Present-day composite materials mimic this fine detail.
One biomimetic design used hundreds of millions of times each day comes from starfish ossicles. The strength of the ossicle is derived from the molecular criss-cross formation of calcium carbonate compounds. This excellent design has been applied to stiffen the fillers in the rubber tires used on cars and trucks.