10 Little-Known Facts About Abalone

Abalone ("sea snails") are a type of marine gastropod mollusk that typically occur in the temperate and tropical seas of New Zealand, South Africa, Australia, North America, and Japan. They vary in size—from an inch to a foot—and have flat-ish, ear-shaped shells decorated with spiral designs. There are an estimated 35 species and 18 subspecies, seven of which can be found in North America. 

From their superior spawning abilities to the challenges they currently face, here are 10 little-known facts about abalone.

1. Abalone Are Primitive Animals

Like other archaeogastropods, abalone exhibit primitive (simplistic and largely unevolved) anatomical features, such as bilateral symmetry. They have hearts and a cerebral ganglion that supply nerves to sensory organs, but they don't have brains or any mechanism to coagulate blood (making it likely they'll bleed to death if deeply cut). Their muscular, suctioning feet take up most of their bodies and help the mollusks cling to rocky surfaces.

2. They Have Highly Desirable Iridescent Shells

While they may look unexciting on the outside, abalone shells contain a thick inner layer of iridescent mother-of-pearl that has long driven humans to collect them and turn them into home decor and jewelry. Besides being mesmerizingly colorful, their shells are also believed to be 3,000 times stronger than a single crystal of calcium carbonate, the mineral of which they're made.

3. Red Abalone Are the Biggest and Most Prized

Of the estimated 35 species of abalone, red abalone (Haliotis rufescens) are largest and most sought-after by mollusk hunters. The brick-red species can grow to be a foot long if it's lucky enough to avoid being plucked from the North American West Coast, the only place in the world it occurs, during its lifetime. 

Red abalone were once a hot commodity in California, where they're widely eaten, but the state enforced strict fishing regulations due to rapid species decline. Now, red abalone smaller than 7 inches long (less than 5 years old) can't be harvested in the state.

4. They Can Spawn Millions of Eggs at Once

Young abalone spawn a few thousand eggs in the initial years of reproduction, but when they grow older and larger, they spawn millions. (An 8-inch abalone can drop 11 million eggs at a time.) Warm water can create stress and often leads to a shortened breeding season. Meanwhile, studies have shown that one abalone spawning prompts others in the area to spawn as well.

5. They Have an Extremely Low Survival Rate

Abalone with shells less than a quarter-inch long suffer a mortality rate of 60% to 99%. They are most likely to be preyed upon by filter feeders within the first 24 hours of being released, when they're actively searching for a suitable habitat. When they are born on a farm, their survival rate increases. The few that make it to adulthood can live for 40 years.

6. Abalone Are Often Farmed

Today, more than 95% of the world's abalone come from aquaculture. They're bred and raised for food in saltwater pens onshore or in suspended cages in the ocean. It takes them three to four years to reach a marketable size, about five abalone per pound. The Food Agriculture Organization of the United Nations (FAO) says abalone is one of the most expensive of any seafood in the world.

7. They're Also Sold on the Black Market

The strict regulations around harvesting abalone has resulted in tons of them being taken illegally and sold on the black market. Abalone poaching is rife on the West Coast of North America, where a single full-sized red abalone can retail for $100, and in South Africa, where local species are poached and marketed by gang cartels. Some sell for hundreds of dollars per pound.

8. They're Considered a Delicacy

At the price they're sold both on and off the black market, it's no surprise that abalone are considered a delicacy in some countries. It's served fresh and dried in Cantonese cuisine and is traditionally eaten on Chinese New Year. The FAO says China is the world's largest producer and consumer of abalone, producing more than 10,000 metric tons annually and consuming 90% of it.

9. They're a Staple of Indigenous Culture

The Traditional Animal Foods of Indigenous Peoples of Northern North America says several West Coast tribes collected abalone for their meat (normally consumed raw) and shells, which were made into tools and jewelry. They were harvested not only by Native Americans, but also by Indigenous people in Africa and Australia. Their cultural and historical significance is one reason why they've recently been granted governmental protection. 

10. Two Abalone Species Are Endangered

White abalone were the first invertebrates to be listed as endangered under the Endangered Species Act in 2001. Black abalone earned the same status 10 years later. Both endemic to the North American West Coast, these species have experienced serious population declines due to overfishing, low reproduction rates (a result of low population density), disease (such as withering syndrome), and oil spills. 

Fishing for black abalone has been illegal since 1993 and white abalone since 1996. California closed a large commercial abalone fishery partially responsible for declining populations in 1997. Since then, the state has periodically banned abalone diving to allow the species to recover.