Dendrobatid Biology, Species, and Captive Husbandry
This will be the first of likely many articles about Poison Dart Frogs (I may refer to them as dendrobatids or PDFs, so everyone's on the same page).
But this is a fish forum!
In my experience over the years with freshwater aquarium keeping, I have noticed a trend that happens among many fish keepers: they get more complex in their set ups and their species. Initially, we all started with something simple like a goldfish in a 10 gallon tank with gravel and a plastic plant, then as we learned, we upgraded. We get more tanks, a create a more enriching environment for the animals, possibly going onto, what I would consider, the most difficult type of aquariums: planted tanks. It takes quite a bit of skill not only to keep a number of species of fish, but also a number of species of plants, and all get them working together. It's certainly a sight to behold.
So what does this have to do with Dart Frogs? Well, I would say that it's the next step in the progression. My last aquarium was/is a planted tank, and I really liked the looks of it, and then gone introduced to vivaria, and saw the next set of tanks. Don't get me wrong, I love my frogs, but doing these vivariums, you have to have a certain appreciation for plants. Actually, in my experience, I see that a lot of people have the same sort of progression. A lot of people in the PDF hobby came from the saltwater reef or planted tanks hobby, which is understandable, if you think about it. Dendrobatids are simply the terrestrial equivalents to reef (and many FW) fishes in terms of color and intrigue.
The family Dendrobatidae comprises of over 200 species that occur in Central and South America. These frogs range from 13mm in length to about 50mm in length, so these frogs are rather small for frogs, which, for the most part, makes them excellent candidates for vivaria. These frogs are diverse in color, patterns, and behavior. In regards to color, dendrobatids come in all colors of the rainbow. Dendrobatids are considered aposematic, meaning that they have bright colors that advertise their unpalatability to predator (I know what you're thinking, “keeping toxic animals? You're crazy.” I may be crazy, but I'll tell you why keeping dart frogs is not crazy a little later). These frogs, by and large, are diurnal (otherwise, not much point to being brightly colored), which is rather unique for most frogs. Not only that, but dendrobatids are the most polymorphic group of vertebrates (maybe animals in general) on our earth. The species that I study for my Masters Research, Oophaga pumilio, is the pinnacle of this phenomenon.
The above pic represents 12 different morphs of . These species comes in well over 30 different morphs.
In regards to behavior, dendrobatids are unique among frogs in that they exhibit several different varieties of reproductive strategy. All dendrobatids exhibit parental care, but some more so than others. There are three different strategies that dart frogs employ: deposit and go, non-obligate egg feeders (often called “thumbnails” in relation to their size), and obligate egg feeders. Unlike make of the species of frogs in North America, dendrobatids deposit their eggs on a moist leaf buried beneath the leaf litter. The eggs develop into tadpoles in about two to three weeks. Over this time, the male typically waters the eggs periodically by urinating on them (which really is mostly water). From there, they will hatch. At this point, the parents return to collect the tadpoles. The tadpoles will use their mouths and adhere to the parents' backs, at which point the parents will transport them to a water source (which, depending on the species, will be a few drops of water in a bromeliad to a small puddle). For the deposit and go strategists, this is the end of parental care; the tadpoles are left to fend for themselves. For the non-obligate egg feeders, the male will call to the female and get her to visit the tadpoles and lay infertile eggs for the tadpoles to eat. Fortunately for the tadpoles, if dad forgets about them, they can still manage by eating detritus and drowned insects. For the obligate egg feeders, this is not the case. Typically for these species, they deposit tadpoles in very minute amounts of water, without nutritional sources, so the tadpoles need the eggs from the mother otherwise the tadpole will die.
Dendrobatids, of course, exhibit other behaviors. Many are rather territorial and will fight with one another (which can kill frogs). Given enough space, these conflicts are rare, but still entertaining. Frogs will sumo wrestle with one another. I kid you not. The idea is to push the opponent over and pin him (generally it's between males, but sometimes females will fight too). They'll put one another in headlocks, pin, flip, and everything else you can think of. I can't think of many things that are more entertaining than seeing two frogs only 2cm long bouncing around trying to pin one another.
Two adult male Oophaga pumilio in a territorial fight. The Chi-Chi-Chi in the background is this species' call
And finally size, dendrobatids can be tiny (smallest species is 13mm long). With the variation in size, they inhabit a variety of niches in the jungle. Many of the larger species are completely terrestrial, whereas some of the mid to small species (20mm and less) are highly arboreal. Given the variety of sizes, these species cover many different areas within the jungle. You can find frogs hoping around on the ground to frogs hopping around 60 feet in a tree.
Adult Oophaga pumilio, roughly 17mm long, next to an adult Minyobates claudiae, roughly 13mm long.
So as to give me things to talk about in the future, I won't go into great detail about vivaria, food production, species, breeding, etc, but I will mention a few things to keep your appetites whetted for the next installment.
For being such small animals, they do require a bit of space. The absolute minimum size tank for a pair of frogs is 10 gallons, and generally that is frowned upon. Many breeders will use 15 gallons or 20H for their vivaria. What actually is getting to be more and more popular is the use of Exo-Terra vivariums because of the easy conversion and front opening access. Vivarium construction can be a task in and of itself, and actually can have some application in the fish keeping hobby. I'll go more into that in a later issue, though. Many people like to incorporate both and make paludariums, which have some success (mostly to keep fish and frogs, you need a very large tank). Most vivariums are heavily planted that have a variety of bromeliads, ariods, and orchids. Unlike aquariums, the most maintenance that frog vivariums require are cleaning the tank glass (mostly so you can see the frogs, not really for the frogs' benefit) and making sure that the tank is well drained (which occurs with vivarium construction).
Typical dendrobatid vivarium with many bromeliads for hiding and rearing as well as leaf litter to help culture microfauna within the tank
Dendrobatids are, among many reasons, amazing because they get their toxins from what they eat (which in the wild, is particular species of ants, beetles, millipedes, and mites). Phyllobates terribilis is the most toxic vertebrate in the world. In one 5cm long adult frog, it has the capacity to kill 20,000 mice or 100 humans. But these toxins are all diet based, so P. terribilis in captivity are completely harmless. This is because the staple of dendrobatid diets in captivity are fruit flies. You have to culture fruit flies on a regular basis (which is often regarded as the most difficult part of PDF keeping). Most breeders, though, mix it up and culture other insects and arthropods such as dwarf woodlice, pinhead crickets, and springtails.
Dendrobatid species range in difficulty much the same way that fish differ. Some are as easy as Oscars and others are as temperamental as Discus. Generally, the larger species make better beginner frogs. Some of the best beginner frogs include Dendrobates leucomelas, Dendrobates auratus, and Dendrobates tinctorius. Intermediate frogs generally are considered to be many of the thumbnails due to their size, although the best ones to start off with those are Ranitomeya imitator, Ranitomeya ventrimaculatus, and Ranitomeya lamasi. The advanced frogs are generally considered to be the obligate egg feeders like Oophaga pumilio.
Ranitomeya imitator - Considered an Intermediate Frog (roughly 20mm long)
Oophaga pumilio - Considered an Advanced Frog (roughly 24mm long)
As one would guess, there are a variety of levels of ease in breeding dendrobatids. Some breed like rabbits (many of the beginners, for example), whereas others, it's considered good to get a dozen offspring over the course of a year (like the obligate egg feeders). This largely has to do with the ability to rear eggs artificially or having to let the frogs rear the young. For instance, currently for my D. leucomelas, I have a batch of 6 eggs, 20+ tadpoles, and 8 froglets from a trio of adults.
So this is an introduction to the world of Poison Dart Frogs. They have fascinated me to the point that I've devoted my Masters (and likely PhD) to studying them. I covered a bunch of the basics to PDFs, but I haven't even scratched the surface in regards to their world. Look for more articles about dendrobatids in the future!
All photos and videos taken by MonarchzMan