TAXONOMY
Phylum: Mollusca
Class: Gastropoda (slugs, snails, nudibranchs, abalone)
Order: Archaeogastropoda (sea snails)
Family: Haliotidae (abalones)

Genus/species: Haliotis rufescens

GENERAL CHARACTERISTICS: The red abalone is a large limpet-like snail with a flattened and rounded shell. The shell can reach up to 30 cm (11.8 in) in length and is usually brick-red and overgrown with fouling organisms. Color varies with diet and varies between aquamarine, green, or white. Water enters anteriorly through row of holes parallel to the rim of the shell and exits posteriorly carrying waste products and gametes. When in danger, the abalone clamps its shell tightly to the substrate, protecting soft parts of its body. The shell’s color is influenced by the animal’s diet. The red color is from the pigment phycoerythrin consumed in its red alga diet. Color varies with a diet of brown algae (varies between aquamarine, green, or white).

DISTRIBUTION/HABITAT: Red abalone are found from Oregon to Baja California. They are uncommon in the lower intertidal zone in rocky areas with heavy surf. Most are now found at six to 17 m (20 to 56 ft) depth in central California.

 

DIET IN THE WILD: Small abalones feed on diatoms and algae; larger animals browse the seaweeds. Red abalone eat algae, especially red and brown species. Usually foraging at night, they trap drifting pieces of algae (kelp) with the tentacles that extend from the foot. The algae is then carried by the foot to the mouth, and is torn and consumed with by the radula.

flickr Feeding Video http://www.flickr.com/photos/cas_docents/6393536637/in/set-72157626486149324

 

PREDATORS: Sea stars, crabs, octopuses, sea otters and human divers are among the abalone’s primary predators.

REPRODUCTION: After spawning takes place, fertilized eggs sink. Larvae develop in the plankton until they settle to the bottom, metamorphose, and begin to graze. Growth slows with increasing size and age. Mortality is very high in the planktonic stages. Mature individuals can live more than 20 years.

REMARKS: Red abalone are highly endangered due to overexploitation by the abalone fishery. The population plummeted in the late twentieth century, but poaching continues to be a problem. California passed many strict regulations to protect the red abalone: abalone smaller than 20 cm (8 in) in diameter are protected, the canning of abalone is prohibited, and the shipment of fresh or frozen meat out of California is prohibited. Red abalone is the only species that can still be fished. Aquacultured abalone is now increasingly available.

Abalone blood is blue-green and cannot clot making injury possibly fatal.

Red Abalone Shell19600303421_7eae835178_z

Color of Life note: Iridescence is caused by two or more semi-transparent, inorganic and/or organic surfaces that cause multiple light reflections. An example found in our tidepool is the Red Abalone inner shell surface which produces an impressive vibrant luster when exposed to light.  The aragonite and conchiolin secreted by the abalone in forms a crystalline structure that reflects light, causing the shell’s iridescence. The inner surface of the shell is known as mother-of-pearl, or nacre. Ref: California Academy of Sciences, Color of Life Exhibit 2015   Jewelry is still made from abalone shells and is quite popular.                        Ref: www.best-deal.com/search/landing/query/red+abalone+shells...

 

Other references

Marine Biology Coloring book, T.M. Nielsen, 2nd Ed. Harper Resource 1982, 2000.

Encyclopedia of Life  eol.org/pages/620396/details

Monterey Bay Aquarium  www.montereybayaquarium.org/animal-guide/invertebrates/ab…

California Fish and Game www.dfg.ca.gov/marine/pdfs/response/abalone.pdf

Ron’s flickr https://www.flickr.com/photos/cas_docents/6393536637/in/album-72157608597736188/