Invertebrates
Abalone
Haliotis · also called abalones, ormer
An abalone’s shell hides one of the ocean’s most striking materials just beneath its plain outer surface: a shimmering, iridescent layer of mother-of-pearl that shifts colour with the light. That same desirability, alongside genuinely excellent flesh, has driven several abalone species to the edge of extinction through decades of overharvesting the slow-growing animal has struggled to recover from.
Overview
Abalone, genus Haliotis, are large sea snails found clinging to rocky coastlines worldwide, especially in cool waters rich in kelp. A single, flattened, ear-shaped shell, lined inside with iridescent nacre, houses a broad muscular foot that grips rock with remarkable strength.
Prized to the point of crisis
A row of shell holes handles both breathing and reproduction, but it’s the abalone’s slow growth and late maturity, combined with decades of intense harvest and continuing illegal poaching, that have pushed several species toward serious decline — one that population recovery struggles to keep pace with even under strict protection.
Status
Endangered and decreasing for several species — slow growth means recovery from historical overharvesting remains a genuine, ongoing conservation challenge.
Abalone: common questions
Why is the inside of an abalone shell so shiny and colourful?
The inner surface of the shell is lined with a thick layer of nacre, also known as mother-of-pearl, made up of microscopic layers of a mineral called aragonite arranged in a way that scatters and reflects light, producing a shifting, iridescent play of colour depending on the angle it is viewed from. This same nacre layer is what makes abalone shells so popular for jewellery, buttons, and decorative shell inlay work in various craft traditions worldwide.
What are the holes along the edge of an abalone shell for?
The row of small holes running along one side of the shell serves a dual purpose, allowing the abalone to expel water that has passed over its gills after breathing, and also serving as the route through which the animal releases eggs or sperm directly into the surrounding water during reproduction. As the abalone grows, older holes toward the rear of the shell are gradually sealed over while new holes form nearer the growing edge.
Why have so many abalone species become endangered?
Abalone has long been considered a highly desirable food delicacy in numerous cultures, and this demand drove decades of intensive commercial and recreational harvesting that, combined with the species' naturally slow growth and late reproductive maturity, pushed several wild abalone populations into serious decline. Ongoing illegal poaching, driven by the high prices abalone meat and shell continue to command on black markets, has further hampered recovery efforts even in areas where legal harvest has been significantly restricted or banned outright.
Is an abalone more closely related to a clam or a snail?
An abalone is a type of sea snail, or gastropod, possessing a single, flattened shell rather than the two hinged shells characteristic of clams, mussels, and oysters, which belong to a different group of mollusks called bivalves. Instead of being enclosed between two shell halves, an abalone's soft body clings to the underside of its single shell using a broad, muscular foot, gripping tightly to the rock surface it lives on.