Natural History

• Coelomate - body cavity lined by mesoderm (like a stomach)
• Protostome - cleavage determined as larva
• Trocophore larva
• All organ systems present and well developed
• Respiratory organs=gills

• Open circulatory system with pumping heart, vessels, and blood sinuses
• Fleshy mantle
• Secretes shell
• Protection from predators by tucking itself into the shell
• Radula, which is a protusible rasping tongue-like organ for eating.
• The radula looks like small hooks on a tongue and works like a conveyer belt, moving back and forth to rasp or break food and bring it into the mouth.
• Holes on Shell function as openings for the water that passes over the gills to exit through
• Feeds on drift algae
• Primarily eats seaweed, Macrocystis pyrifera or Egregia laevigata
• Lives in subtidal/intertidal zones and in crevices to 6m
• Ranges from Mendocino, California to Cabo San Lucas, Baja California

• Predators are octopus, starfish, fish and humans
• Other animals may prey on their larvae
• * There has been a drastic decline in Abalones along the CA shores due to Humans foraging for Abalones
• In Palos Verdes, for example, the average density of black abalone was 2.8 m^-2 from 1975-1979.  But the density shrunk to a mere 0.03 m^-2 1987-1991 (Miller and Lawrenz-Miller 1993).  Miller and Lawrenz-Miller intervied Captain Tim Sawyer, California Dept. of Fish and Game who worked at Palos Verdes from1979-1982,  and he said it was common back then to contact people carrying a "few hundred" black abalones.  In one month he wrote 93 citations for people taking black abalones, in 1985 34 citations were written, 46 in 1986, 3 in 1987, and one in 1988.
• They may compete with tube worms for living space under rocks.
• Increased water temperature may make them more suceptible to infection (Miller and Lawrenz-Miller 1993).

• Procted by Law - there is a minimum number and size that can be harvested
• H. cracherodii rarely gets to be 13 cm
• Usually harvsted when they get 8 cm in length (legal size in CA)
• Rates of recolonization and recovery of locally depressed or extirpated black abalone populations are likely to be slow despite harvest restrictions. (Elseviar Science B.V. 2000)
• More abalone are found under Marine protected areas and in one experiment one-third of them were found under urchins' spine canopy (Rogers-Bennett and Pearse)
• Between 1992-1995 there has been a 97% reduction in Black Abalone at the Government  Point (near Point Conception).   Declines are due to Withering Syndrome which has now reached central California and is progressing towards northern California. (Altstatt, Abrose et. al.)