Unlike man, most animals don't have the luxury of choosing where they live. Animals inhabit or adapt to certain niches because conditions such as availability of food, protection from predation, presence of the same species and reduced competition from other more aggressive species, are optimum for survival. These needs can be quite specific with some animals while others are adapted to a wide range of environmental factors.

The lowly barnacles, as most of us see them, are not very exciting animals. They just sit theresharp, little grey things that cover the rocks, cut our feet when we walk barefoot on the beach and tear up the bottoms of our inflatables. Generally they seem to have few redeeming qualities at all. But to the careful observer and underwater photographer they are a fascinating and beautiful creature.

Barnacles inhabit most of the world's oceans. They can be found growing on the usual places such as rocks, pilings and the hulls of boats, or in some not so usual places like on drift wood and kelp mats floating far out at sea. And then there are some, such as the whale barnacle, Coronula diadema that grows quite happily on the bellies of Humpback whales in Antarctica.

Several species of barnacles inhabit Canadian coastal waters in specific habitats. Careful observation of a steep shoreline during a very low tide will reveal a definite pattern, or zonation, to the life that inhabits this area. The acorn barnacle is the one we are most familiar with and the one we see most frequently along the shore. Closer scrutiny will often reveal two distinct species of small barnacles living together, but the range of one will extend somewhat higher while the second species will extend deeper than the other.

These small barnacles are adapted to life in a violent world. They survive quite happily in the harsh and varied conditions afforded by the exposed shore, battered by waves during storms at high tide, exposed to freezing temperatures during low tide in winter, drenched by freshwater when it rains and baked by the sun when the tide recedes in the summer. Few animals are able to survive these varied extremes.

Below the low tide line, in the subtidal zone, other barnacles lead a more consistent existence. The giant acorn barnacle, Balanus nubilus, attaches itself to rocks and pilings down to a depth of 60 feet and may reach six inches in diameter and four inches in height. Its large finger-like feeding organ can be seen waving through the water trapping small plankton that drifts into reach.

In areas of high current or on the crest of reefs that break the surface at low water, we find the goose neck barnacle, Pollicipes polymerus, one of the most interesting and beautiful members of the barnacle family. When danger threatens, most barnacle species can withdraw their delicate feeding appendages, close up completely and protect their entire body within a hard shell until the threat passes. But the goose neck barnacle is attached directly to the rocks with a muscular stalk sheathed in a tough, leathery covering. The barnacle can reach four inches in height and is crowned by a few shell plates which protect only the most vulnerable parts. Growing in dense colonies called hummocks, protection for the goose neck barnacle is afforded by sheer numbers.

Barnacles are hermaphroditic, possessing both male and female reproductive organs. When mating, a long snakelike penis can be extended several body diameters to impregnate nearby barnacles. Fertilized eggs are held within a special sac inside the barnacle until they have developed into the free swimming larval stage called the nauplius. The release of the nauplius tends to coincide with the springtime bloom of phytoplankton, a handy food source for the larvae as they continue their pelagic existence for a few weeks, through several more growth stages. Finally they settle as cypris larva and crawl around the bottom 'tasting' it for suitability. While hanging on with one antennule it will taste with the other, and, if unsuitable, the larvae will swim away to another spot and repeat the process. Several factors dictate a suitable settling spot including the presence of other members of the same species or the faintest traces of their past habitation in the area. When the right spot is found, the cypris larva goes into a head-down position and a special and very strong glue is secreted by a gland in one of the antennae and metamorphosis to the adult form begins.

The oceans and shorelines are filled with myriad lifeforms that we often take for granted. But they are all important elements that make up the delicate marine ecosystem and a source of fascination when we take the time to observe and learn about them.