This photo of a northern abalone’s (Haliotis kamtschatkana) epipodium shows the detail of this sensory structure, which is an extension of the foot. The frilly looking epipodium with its many tentacles allows the abalone to sense its environment, find food and become aware of a predator. If danger is sensed, the abalone will retract its epipodium with tentacles under its shell and clamp down tightly against a rock. The foot is usually tan, and the epipodium can be a combination of brown, tan and green often with a slightly vertically striped pattern.
For respiration, the abalone has large openings on its upper shell surface that allow the animal to pass oxygenated water over its internal gills.
Abalone populations worldwide have been in trouble due to over-harvesting and degradation of habitat. Even though there is a fishing ban on the only species of abalone in the Pacific Northwest, the northern abalone, their population continues to decline. This may be due to the fact that abalone are broadcast spawners, which means that the males and females release their sperm and eggs into the water for fertilization. The problem is that when the density of spawning adults is too low there is less of a chance of fertilization taking place, so reproduction may not be successful. Efforts are underway to attempt captive breeding programs with the goal of increasing wild populations in the Pacific Northwest. The IUCN (International Union for Conservation of Nature) has listed the northern abalone as “Endangered”. The northern abalone can grow to seven inches (18 cm) across, with a range including Japan, Siberia, and southern Alaska to northern Mexico.
