Showing posts tagged as "elasmobranchs"
A Bat Ray Gets a Bath
No one likes ticks. Least of all a fish.
That’s why Senior Aquarist Erin Lyman and her team give freshwater baths to our beautiful bat rays every eight weeks. It’s a concept any pet-owning person can understand. Of course, these aren’t technically ticks—they’re tiny, three-millimeter flatworms. But, just like ticks on a dog, they make life unbearable for bat rays, attaching to skin, eyes and gills. If ignored, they can create vision problems, infections and all manner of misery.
But after just four minutes in freshwater, the parasites fill with water (due to osmotic pressure), burst, and fall off. For a fish, it’s the best bath ever.
Where do they come from?
The Monterey Bay Habitats exhibit—like all the displays in the Aquarium’s Ocean’s Edge wing—takes in water from the bay. This connection to the open ocean is one of the reasons our exhibits look so natural. But while bay water brings in many things we want, like tiny plants and nutrients—it also brings in a few that we don’t—like flatworms.
In nature, bat rays (Myliobatis californica) can scrape off the tiny ticks naturally as they move along the seafloor. But in the busy environment of our exhibit, this doesn’t always happen. That’s when we intervene. A total of four people—two in the water, and two above—are needed to gently urge the 25-pound rays into a sling, lift them clear of the water, and place them in the freshwater bath. It’s all over in a few minutes. It’s a process we also use with our giant sea bass and other fish, and was pioneered at the Aquarium.
Over the years our aquarists have tried many different methods to treat the pesky parasites, including filtration, chemicals and removing them manually. They also supplement the ray’s diet with vitamins and live oysters to strengthen their immune systems. But when it comes to getting rid of the nasties, nothing works quite as well as a bath. Our two large rays have reached the ripe old age of 10, so we must be doing something right!
Erin and her colleagues presented the technique at the International Elasmobranch Symposium at the Aquarium in early November, and her findings will eventually be part of a husbandry manual.