Most folks have seen the colorful and enchanting poison dart frog displays in museums. The Berkshire Museum Aquarium has a great one. Go see it if you haven’t already! Did you ever think about what those frogs are eating? Not poison plants or arthropods I can assure you. What they eat are drosophila flies, you know them as fruit flies. These flies, however, don’t fly. They have been bred to not use their wings. There are two species: D. Hydei, they have bright red eyes and D. Melanogaster “gliders”.
John & Scott at the museum have a series of these fruit fly cultures going that once set up, provide and endless supply of food for these frogs. Its a simple but time consuming process and its kind of tricky to do. But I like insects so I figured I could do this for them (since I stole their intern away to be my snail research assistant).
First the fly food is measured out into a plastic container. It smells good. There are chunks of dried fruit, oatmeal and specks of anti-fungal and anti-bacteria substrates.
Then about 150mls of distilled water is mixed in so that its thick, but not too thick that the flies get stuck in it. Thin, but not so thin the flies drown.
On top of that goes excelsior, that curly wood shaving stuff. It is the material that the flies hang out in, mate in and sleep in. Yes, fruit flies, with their short one week life span: sleep. Seems like a waste of time when you only live 7 days, but apparently sleep is a necessity of life. They lay eggs and pupate on the sides of the containers.
Once the colonies are matured, the flies are dumped into a cup with vitamin powder and sprinkled into the terrarium with the frogs. They gobble them up! Its fun to watch.
Because these frogs eat fruit flies and not poison plants or arthropods, they are not poisonous. This is good because sometimes they try to jump out of the tank and we have to touch them. Good to know I won’t get sick or die.
Many of the wild frogs secrete lipophilic (likes oil) alkaloid toxins through their skin. These poisons are a chemical defense from predators. The most poison species is Phyllobates terribilis. Scientists haven’t yet figured out if the frog makes the poisons, or sequesters them (stores them up) in their poison glands from foods that they eat such as ants, centipedes and mites. And we think that because the captive frogs do not eat this poisonous diet, this makes them not toxic. But the science behind this is still waiting to be determined.