Oakleaf Toad
The oakleaf toad, Grima frondiforme, is a true toad from the undergrowth of temperate woodlands in Europe and Asia with excellent camouflage. It is descended from the common toad.

It gets its name from a peculiar fleshy outgrowth on its back that looks exactly like a fallen oak leaf. The toad lies partly buried in the leaf litter, totally camouflaged and quite motionless except for its round, pink tongue which protrudes and wriggles about just like an earthworm. Any smaller animal, such as a very small mammal, that approaches to investigate falls victim to the toad's powerful jaws. The animal's only real enemy is a predator rat.

Oakleaf toad attack

The oakleaf toad lures its prey with its long, wormlike tongue.

These two creatures, the oakleaf toad and the predator rat, have a curious relationship. Within their bloodstreams lives a fluke that spends the juvenile stage in the toad and the adult stage in the predator rat. When the fluke approaches adulthood it produces a dye that turns the leaf-like outgrowth on the toad's back bright emerald green. As this happens in winter the toad becomes highly conspicuous and is quickly eaten. In this way the fluke is transferred into the body of the predator rat, where it becomes sexually mature and breeds. The fluke's eggs return to the toad through the predator rat's feces, which are eaten by beetles that are preyed on by the toad. As the fluke needs to spend a period of at least three years growing in the toad's body before it is ready to parasitize the predator rat, and as the toad is sexually mature at 18 months, all toads have the opportunity of reproducing before being exposed to predation.
Tainted toad

Leaf outgrowth dyed green by mature fluke.

Untained toad

Untainted leaf outgrowth providing camouflage.

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