Frogs - But No Tadpoles

There is a group of frogs in northern Queensland which do not have a free-swimming tadpole. These frogs are very small and are known as Microhylids: which means 'tiny tree frogs'. They occur elsewhere in the world besides Australia but within Australia, they are confined to the Wet Tropics.

Microhylid adults are usually under 2cm (¾ inch) in length and they frequently call while hiding under tree bark, rocks or leaf litter. They take some patience to find because they can squeeze into the tiniest hideyholes. They also share a 'ventriloquist' quality with many other frogs which makes finding them a real test of willpower.

This group of frogs is commonly called 'nursery frogs' because they lay a small clutch of eggs in very moist soil under rocks, logs and leaf litter. The eggs are coated with a special anti-fungal agent to help the eggs survive in a wet environment. The tadpole actually develops inside the egg and when it has completed metamorphosis, it simply hatches from the egg!

There are two genera of nursery frogs in North Queensland and the majority of their species are endemic to the Wet Tropics rainforest. The first group is the genus Cophixalus and some of these are only found on one mountain top and no other. A couple of these can be found down to 80 metres (260 feet) altitude including the most common Australian microhylid, the Ornate Nursery frog. The call of the Ornate Nursery frog (Cophixalus ornatus) is a nasal 'beeeep' which sounds wonderful reverberating through the rainforest at night.

The other group is the genus Sphenophryne with only three representatives in the Wet Tropics area but those three are more widely distributed through the area's forests. The Sphenophryne species are about as small as the Cophixalus but they tend to have a more rounded, almost rotund body.

One of them - the White-browed Chirping Nursery frog (Sprenophryne pluvialis) has a call that sounds just like the ring of a mobile phone!