Abalone have lived along the Pacific Coast of North America for millions of years. Fossilized shells closely resembling modern abalone have been found in sediments approximately 100 million years old. In more recent times, abalone were important in the economy of all native peoples who dwelled in California's coastal areas.

Recreational interest in abalone increased when wetsuits, diving equipment, individually owned boats, and charter dive boats became readily available. Although harvests have remained high in some areas, particularly in northern California, many other areas are no longer productive.

The state of the resource today is a cause for concern by many interests, including the Department of Fish and Game. Commercial demand is high while the supply is decreasing. Recreational divers often must travel further or search harder for a limit, or a trophy size abalone. Large areas of once productive habitat have been depleted by a variety of causes. Nevertheless, California's abalone species still possess an almost legendary mystique.

In the animal kingdom, abalone belong to the phylum Mollusca, a group which includes clams, scallops, sea slugs, octupuses, and squids. Molluscs are worldwide and predominantly marine. They have a soft body surrounded by a mantle, an anterior head, and a large, muscular foot. Molluscs are best known for their beautifully formed and colored calcareous shell secreted by the mantle.

The abalone join other snails, whelks, and sea slugs in the class Gastropoda. Members of this class have one shell, as opposed to clams with two, or the shell may be lacking altogether, as in the sea slugs. The spiral structure, so common in snail shells, is flattened in the abalone and may be obscured by fouling and shell boring organisms.

Abalone are members of the family Haliotidae and the genus Haliotus, which means "sea ear," referring to the flattened shape of the shell. The name "abalone" is probably derived from the Spanish-American word "aulon" or "aulone."

The most conspicuous part of any abalone is the shell, with its row of respiratory pores. Shells are prized because of their inner, iridescent layer. The muscular foot has strong suction power permitting the abalone to clamp tightly to rocky surfaces. A column of shell muscle attaches the body to it's shell. The mantle circles the foot as does the epipodium, a sensory structure and extension of the foot which bears tentacles. The epipodium projects beyond the shell edge in the living animal. The epipodium surface may be smooth or pebbly in appearance and it's edge may be frilly or scalloped. It is the most reliable structure for identifying abalone species.

The internal organs are arranged around the foot and under the shell. The most conspicuous organ, the crescent-shaped gonad, is grey or green in females and cream colored in males. It extends around the side opposite the pores and to the rear of the abalone. The abalone head has a pair of eyes, a mouth and an enlarged pair of tentacles. Inside the mouth is a long, file-like tongue called the radula, which scrapes algal matter to a size that can be ingested.

The gill chamber is next to the mouth and under the respiratory pores. Water is drawn in under the edge of the shell, and then flows over the gills and out the pores. Waste and reproductive products are carried out in this flow of water.

Since it has no obvious brain structure, the abalone is considered to be a primitive animal. However, it does have a heart on its left side and blood flows through the arteries, sinuses and veins, assisted by the surrounding tissues and muscles.

Abalone on the Pacific Coast are found on rocky intertidal and subtidal areas from Baja, California to Alaska. Each species prefers a particular habitat which appears related to the local sea temperature. For instance, red abalone in cold northern California may be found intertidally (the area between high and low tide), when in warmer southern California they usually occur subtidally (in the water below the low tide mark).

Small abalone seek cover in crevices, under rocks or in the spines of sea urchins. This behavior probably results from an abalone's instinctive attraction to dark places, which protects them from many predators. Though small abalone hide during daylight hours, they are active at night. Small red abalone are known to move hundreds of yards. As abalone grow larger, and become less susceptible to many predators, they seek the open, more visible locations where food is more available.

There are eight species of abalone in California (some scientists feel there are only seven, see threaded abalone). Economically, the red, pink, green, white and black abalone are the most important because of their size and abundance. The flat, pinto and threaded are smaller and less common.

Because sport and commercial fishing regulations differ, and because they vary from time to time by area and species, it is important that people know current regulations and that they can identify the species. Abalone identification is best learned in the field with live specimens and knowledgeable assistance.

Link To Abalone Resource Status and Management Options from the Dept of Fish and Game - 4/23/01