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Poison Frogs - Breeding

written by Erik Poelman.

Contents :

Poison frog breeding

Eggs

Tadpoles

Poison Froglets

Poison Frog Breeding

Usually frogs can start breeding when they are 12 months of age, some species tend to take a little longer. In their natural habitats frogs will be activated to start breeding after a relatively dry season changes into a rainy season. In the vivarium this can be simulated by taking a period without rain first for several weeks, followed by heavy spraying at least twice a day. In my tank the frogs start calling after the "rain" is finished, the leucomelas has a high pitched rallt like call which at first sounds like a ventilator that ticks. Each species and even each male has a different call. Some call types are quite powerful canary like rallts (E. tricolor, D. leucomelas, P. vittatus), single or multiple clear notes (E. femoralis, E. bilinguis) or others are more gently barely audible sounds (D. ventrimaculatus, D. tinctorius). Frogs need to be fed heavily to be in the right physical condition to even think about breeding.

Males usually call from an elevated position above the leaf-litter to attract a female. If a female fancies the idea of breeding she will approach the calling male. He will then start the courtship behaviour and display to the female that she should chose him as mate. The different species of the Dendrobatidae family have fairly different courtship behaviours, just before they mate. In general the male will lead the female to a site where he likes the female to lay her eggs. The types of these sites vary between the species. Most frogs from the genus Epipedobates, Phyllobates and Dendrobates deposit their eggs inside the leaf-litter. These sites are dark and moist and can be simulated in a terrarium by adding artificial egg deposition sites. The most commonly used is a petri dish covered by a plastic bowl or a halved coconut to make a breeding hut.

Some species from the Dendrobatidae family use the leaf axils of bromeliads as deposition site for eggs. If you keep species with such a breeding ecology, you should either add some bromeliads to your terrarium or use artificial sites like film cans or small plastic boxes. Eggs are commonly laid away from the water so do not put water inside these artificial sites (except for D. ventrimaculatus).

The courtship behaviour can last for several hours and normally several deposition sites are visited by the pair before the pair actually starts mating. If the female is out of sight, the male would start calling to attract here again and start moving towards a suitable deposition site. Occasionally he will stop to see whether the female is still following and stimulate her by calling. Inside the deposition site the courtship continues and the frogs start a mating `dance` consisting of mutual stroking, cleaning of the surface of the leaf and in some species there is an amplexus position (male holds the female strongly with his forelegs ). In the Dendrobatidae family clutch sizes varies between species from 1 to 40 eggs per clutch. The Epipedobates and Phyllobates species lay larger clutches of eggs, where the genus Dendrobates is very variable in the number, but has generally the lowest number of eggs per clutch (1 to 10). After the eggs are laid the male will fertilise the clutch. However, there are some species in which the male releases his sperm before the eggs are laid. The first few trials are usually not fertilised or are just a gelatinous mass without eggs, but after a couple of trials the pair will produce fertile eggs.

The poison frog eggs

After the eggs are laid one or both of the parents depending on the species starts looking after the clutch of eggs. Most commonly in the Dendrobatidae family the male will take care off the eggs and will guard them against predators and specific females that are often egg robbers in species with a male parental care strategy. This is because the male is less willing to mate when he is looking after a clutch of eggs. Destroying the clutch will make the male available for mating and that is exactly what the female is interested in. Thus keep an eye on the eggs when you have a breeding group with several females (especially in the tinctorius group, but the behaviour can be observed in several members of the Epipedobates genus). Further care for the eggs consist of moistening them and removing (consuming) eggs that are spoiled by fungal infection. In the Dendrobates genus there are two other parental care strategies. In the pumilio and histrionicus group members the female takes care of the offspring. A more complex behaviour can be found in most of the quinquevittatus members. These very small frogs have a biparental care in which both parents look after the offspring.

The eggs can at best not be disturbed for a few days, after that period it is better to take them out of the vivarium, in order to prevent other females to disturb the eggs. Athough there could be benefits of leaving the eggs in the vivarium: The males and in some species females (pumilio and histrionicus group) are less interested in mating, which provides some rest for the females and will benefit the quality of the eggs. In captivity females are reported to lay around 2 times a month, this could cause burn-out of such a female in a year. Leaving the eggs in the vivarium could be positive for the frogs, having a better productivity of frogs is another issue. Perhaps most important; it could be nice to watch the rest of the interesting behaviour to observe and learn from the specific behaviour of the poison frogs.

If one takes the eggs out of the vivarium, they should be kept in a very humid environment, usually a small container is used filled with paper towels and saturated with demineralised water. The eggs can be placed on top of the paper towels. Small holes in the top are required to provide some air circulation. After a few days you should be capable of seeing the eggs develop, the darker spots in the eggs should remain dark for most species and finally develop into tiny moving tadpoles. If the eggs turn white, they can at best be removed.

Egg development

All pictures by and thanks to © Erik Poelman

All pictures can be clicked to see in full view

When eggs of the different Dendrobatidae species are deposited they are fairly large compared to other species. Fertilised eggs in almost all species are black however some species related to D. imitator have white eggs. The picture series shows the development of a single egg from a clutch of Dendrobates ventrimaculatus. The eggs were kept in a petri dish at 21 C.

egg day 1

egg day 2

egg day 3

In the first three days the only thing which you can observe with the human eye is a slight growth in the size of the fertilised egg or zygote. Actually a lot more is going on. Rapidly the zygote is increasing its number of cells by cleavages. The number of nuclei and the amount of DNA is doubled with each division. The egg has a certain polarity, that is a polar axis that establishes a differentiation in the embryo together with a difference in direction of cleavages. Amphibian eggs have a moderate amount of yolk concentrated in the lower half of the egg (vegetal pole), where the opposite (animal pole) contains little yolk. Cleavage in the yolk rich part is somewhat retarded. From day 4 onwards one can observe the different poles. The upper animal pole stays black, where the vegetal pole containing the yolk becomes much lighter in colour.

egg day 4

egg day 5

Day 5 shows the neurula stage of an amphibian egg. Here the gastrulation is in full process. Cells are moving inwards (invagination) and three layers are formed. The outer layer the ectoderm will give rise to the body surface and the nervous system. The picture clearly shows the neural grove that forms the neural tube on the animal pole. The inner layers endoderm and mesoderm later on form the organs (mesoderm) and digestive tube (endoderm).

egg day 6

egg day 7

egg day 8

egg day 9

Day 6 to 9 show the different stages of a tailbud tadpole. You can observe the formation of a tail (left) and the part that shapes the head (right). Still the animal pole is upwards and the yolk in the vegetal pole is clearly visible by colour differences. In the later tailbud stages movement of the embryo can be observed. These embryo stages are remarkably similar in all vertebrates.

egg day 10

egg day 11

egg day 12

egg day 13

egg day 14

egg day 15

Day 10 to 12 show an embryo that is gilled, where the gills can be a few mm in length and clearly visible from the head hanging alongside the yolk belly. Day 13 to 15 show fully grown tadpoles in which the tail and head have developed. The gills and yolk mass are reduced and at day 15 the tadpole will hatch and awaits its transport from the jelly mass to a waterbody by the male.

Clutch pictures

Poison frog tadpoles

After 10 to 18 days (again depending on species, but also temperature) the eggs are matured into tadpoles. In the species with a male parental care strategy the male will return to the clutch of eggs and pushes himself into the jelly mass from which the tadpoles wriggle onto the back of the male. Some species transport whole clutches at one time and are completely covered with tadpoles, others transport them one by one or only a few at the time. Tadpoles are transported to small streams, pools or small water bodies inside tree holes, seed husks or leaf-axils of plants (mainly Helicons and Bromeliads). Most commonly the parents do not look after their tadpoles. However in some species the females transport the tadpoles to small waterbodies inside bromeliads and return periodically to provide a food source by laying unfertilised eggs (pumilio and histrionicus members). Even more complex is the behaviour of some quinquevittatus members in which the male transports the tadpoles, but calls at the deposition sites to attract the female which then lays unfertilised eggs.

Most species have omnivorous tadpoles that will eat all sorts of food from algae, detritus to insect larvae and dead insects. Some species tend to be more carnivorous (D. tinctorius) and eat insect larvae and other tadpoles. The pumilio- and histrionicus group species have tadpoles that fully rely on the nutritive eggs their mother brings them, they are obligate egg feeders. Raising these tadpoles is not at all simple and most tries of artificial food sources (chicken yolk, eggs of other species) have failed. Best is to keep these tadpoles in your vivarium and let the female look after them. Tadpoles of other species can be fed by fish flakes, insect larvae (especially the quinquevittatus members are growing better on small mosquito larvae and cyclops) and milled spirulina algea. Then there are a number of vitamin supplements that can be used to prevent the spindly leg syndrome ( see earlier remarks ). Usually vitamin D3 is required to prevent this from happening. The use of daylight lamps in the tads aquarium is another way of preventing this phenomenon. The froglets will make their own vitamins to obtain the calcium required for their growth even better. Secondly algae are formed by the light that provide a natural food source for the tiny creatures. However, it has become clear that there are several causes of spindle leg syndrome and thus several solutions. It is best to try them all and find out where the problem lies; it might be food source for tadpoles, vitamins or calcium or perhaps bad quality of the eggs and poor condition of the parents (or a combination).

Keep in mind while building your vivarium which species you are planning to keep. Design larger streams or pools for species which need them for tadpole deposition and it might be better not to make large open water for species that do not need them. These frogs are poor swimmers and why risk to loose a frog by drowning when you do not really need such an amount of water. However, small streams and waterfalls are eye catchers in your vivarium. An intermediate design is in this case best; waterlevels should be lower than the frogs height and having several obstacles that are easy to climb.

If you have removed the eggs previously or are able to catch your tadpoles from the vivarium you can start taking care of the tadpoles by hand. Although it may seem difficult for the tadpole to come out of the egg, it is best to leave it to do his job. Trying to help it might permanently damage these tiny and fragile larvae. Tadpoles can be raised in small containers ( like the Polystyrene throw away coffee cups ) and should be kept at a temperature between 20 and 25 degrees C. The small containers should be refreshed with fresh water every day, this could provide such a burden that many people have developed easier systems to provide fresh water without the tedious cleaning. Mostly used ( in many variants ) are a number of cups, connected to a floating medium with drilled holes in it ( wood, Expanded PS), In the bottom of the cups a few holes are made, covered with a fine mesh. This system is placed in a larger aquarium filled with distilled water and kept on a constant temperature with one thermostat and circulating ( and sometimes filtering) pump. The main reason to keep tadpoles separated is that they often have negative influences on each others growth rate. This might be by releasing chemicals ( which provides an effect in the combined container method ) or even by cannibalism. Cannibalistic tadpoles are most commonly found in Dendrobates species as these are often depositing their tadpoles in separate very small water bodies containing sufficient space and food for only one tad to reach metamorphosis. Species that release their tadpoles (most Epipedobates and Phyllobates) in streams are in general not cannibalistic and can be raised in groups.

Tadpole development

All pictures by and thanks to © Erik Poelman

All pictures can be clicked to see in full view

After several months the tads should develop hind legs first and then front legs. When the front legs develop the water level should be lowered to barely allow the tadpole to swim. People often put their froglets in petri dishes that are put under a slight angle so that the froglet can climb out of the water; the tadpole can in fact drown when the water is too high. one can also stop feeding when the front legs emerge, the capacity left in the tail will be absorbed for the rest of the growth, resulting in the reduction of the tail. During the reduction of the tail, also the mouth of the froglet changes from a tadpole to a functional frog mouth. When the tail starts to dissapear, one should transfer the newly arrived froglet to a small vivarium.

Tadpoles can remain on the back of the parent for a few days and after deposition they will still feed on the remains of their yolk mass. The pictures show tadpoles of Dendrobates ventrimaculatus in different developmental stages. They were all kept in plastic cups containing around 30 ml of water at a temperature of 21 C. A piece of oak leave was added to lower pH level. Tadpoles were fed on Liquifry the first week, the period after on fish flakes and dead insects (Drosophila).

The first pictures show a one day old free swimming tadpole. Note the very small size. In only six to seven weeks it grows to a tadpole presented in the following picture. After 8 weeks the hind legs start to grow. At this stage they are just small buds. At the same time the first signs of the yellow back pattern pops up concentrated around the nose and eyes. The fourth picture shows a nine week old tadpole that has some more colour and thin legs. The tenth weak tadpoles have stronger legs and after 12 weeks they are fully grown. You can observe almost all of its back pattern and if you look very closely the first signs of front legs can be observed. The final two pictures show a tadpole of 14 weeks old that has its front legs well developed and freed from the `sack` they were in. In a few days to a week the tail is reduced and its tadpole mouth shaped to a frog beak. After completing the metamorphosis the froglet will leave the water completely and starts searching for small insects.

Poison froglets

The small vivarium in which the froglets are transferred should not exceed 20 litres (5 Gallon), since they have a difficulty in finding food. In such a small area you can keep a number of froglets, since they are peacefull but tiny creatures. Only the larger variants ( like auratus, azureus or tinctorius ) are capable of eating the small fruitflies. Most are reliant on springtails, small mites ( if you have your own fruitfly culture it is easy to breed mites too intentionally ) and other tiny food. The small vivarium should have plenty of food. The dosing of calcium and D3 is difficult with these small food sources, creativity is required here, although after a while most froglets will eat the small fruitflies, which can be powdered better. The froglets are also poor hunters, this is another reason to fill the small tank with food.

After a few weeks of feeding and growing the froglets can be transferred to a larger enclosure for further maturing.

Take care that the water parts are no deep since froglets are poor to very poor swimmers.

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