Just beneath the surface of Yaquina Bay’s brackish water lurks a predator. Its spit is made of acid, and its tongue a ceaseless drill. Littered along the sandy seafloor lies the evidence of its appetite: an array of vacant shells featuring small, perfectly round holes — the remnants of bivalves fallen prey to the voracious moon snail.
When hunting, the softball-sized moon snail puts its best (and only) foot forward, using its mass to envelope and suffocate prey. If that proves ineffective, the real grind begins, with the snail using its radula — a tongue-like organ covered in tiny teeth — to slowly bore into its victim’s protective shell. Once the snail’s teeth breach the shell, it excretes an acidic saliva within, liquefying its prey.
Moon snails are among the largest snail species found in the intertidal zone. Though fairly common, finding one is actually no easy task.
Donning wetsuits and brandishing buckets, a group of aquarists traverses the exposed mudflats, taking advantage of the negative tide, which presents an ideal opportunity to search for fish and invertebrates — species the aquarium is permitted to acquire a limited number of each year.
“They’re called sand collars,” says aquarist Abby, holding an algae-green, rubbery ring spanning the width of her outstretched hands. “Over time, it’ll break down and release larval moon snails.”
She carefully deposits the collar into a bucket of seawater. When she returns to the aquarium, she will begin the process of monitoring and rearing the larvae through their unique multi-phase life cycle.
Moon snails are particularly elusive. The massive mollusks only hunt at night, spending their daylight hours buried and hidden in the silt of the seafloor. Often, the only signs of their presence are what they leave behind: pockmarked shells, trails in the sand, and egg cases.
Abby keeps her eyes fixed on the tidal beds, knowing the chances of finding a moon snail are slim — but never none. Drawn to the side of an exposed pier piling, she focused on a slick strip of white barely visible beneath a mass of seagrass. “It’s probably an anemone,” she says, but decides to check anyway.
Brushing the grass aside, she discovers a large shell atop an even larger carpet of white slime.
“Moon snail!” she exclaims, prompting the group to rush over. With the large Lewis’ moon snail spilling over her cupped hands, Abby and the group inspect the key features while keeping it partially submerged in seawater. They note the diameter of its shell, the heft of its weight, the way its fleshy foot is practically pearlescent in the sunlight. After, she gingerly places the snail in the bucket alongside the sand collars, peering back at it every few minutes while the excursion continues.
Eventually, the team arrives back at the aquarium, where Abby transfers the moon snail to a dedicated quarantine area. As with any new acquisition, the moon snail must go through a standard quarantine period to prevent disease and parasites from entering the aquarium’s assortment of sea life. Only after receiving the “all-clear” from veterinary staff can the predatory moon snail make its public debut in one of the aquarium’s galleries.
But even then, what the moon snail does best will remain elusive — saved for the shadows of the night after guests and aquarists like Abby have returned home and are fast asleep in their beds.
