The buccinid gastropod Neptunea amianta (Dall, 1890) is a deep-water species found off the North American west coast. Typically boreal, the range extends as far south as Punta San José, Baja California with depths usually between 300 and 1500m. In approximately 15 years of video sampling by the Monterey Bay Aquarium Research Institute with remote operated vehicles in Monterey Canyon, N. amianta has been documented from 100-3500m, yet dense aggregations, uncommon in deep-sea snails, seem to occur only between 200-2000m. This range extends the species into the oxygen minimum zone, where oxygen concentrations of the water column fall to such depleted levels that many species are unable to survive here or require special physiological adaptations. Previous research indicates that low oxygen concentrations can reduce shell size in Atlantic deep-sea gastropods; nonetheless, N. amianta, is a giant compared to other deep-sea gastropods obtaining shell heights of 6cm.
Most species in the superfamily Muricoidea, are carnivores, secondarily evolving to omnivore, herbivory, or deposit-feeding. Typical of its family, N. amianta is scavenger and dense aggregations in Monterey Canyon have been associated with every conceivable type of large organic matter such as dead crabs, dead whales, dead cold seep clams, kelp, and wood. The species has amazing fasting potential. In one published experiment, 5 individuals survived 12 months in aquaria without food, after which the experiment was terminated. All five individuals displayed no clear signs of undernourishment and one produced a large egg case with ~75 juveniles during the seventh month. The remarkable fasting potential and the ability to utilize any food resource are likely responsible for its large depth range and high density.
Buccinids have separate males and females with fertilization occurring internally. Females can produce over 1000 eggs in a leather capsule. In N. amianta, egg capsules are stalked and typically 15-25cm high. Multiple stalked capsules, laid by separate females, are found grouped on a hard substrate such as rock outcropping. The utilization of hard substrate may serve the dual purpose of providing a stable base and allow the egg capsule to extend higher off the bottom into more oxygen rich water. The core of the egg stalk is hollow further allowing for oxygenation of the the egg mass. In some Neptunea species, the first few juveniles to emerge from the capsule will quickly consume unhatched individuals.
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