Cute, colorful and deadly

Education | Ocean Park 19 May 2020

Poison dart frogs are renowned for their bright appearance, with their skin's coming in shades of neon red, blue, yellow, orange and gold. But don't ever be fooled by their attractive looks: they are some of the most poisonous creatures on Earth!

The beautiful colors are actually a patent warning signal to alert you that they are extremely toxic. This is a defense mechanism called "aposematic coloration."

Measuring only 2.5 to 5 centimeters in length, these tiny frogs secrete poison onto their skin that can paralyze and even kill predators. The most lethal is a golden poison dart frog, whose poison is deadly enough to kill 10 human adults.

Scientists have discovered that some poison dart frogs' toxin may have medicinal value as a painkiller.

These frogs comprise more than 100 species and are found in the tropical rainforests of central and south America. The indigenous people of western Colombia, known as Choco, have a tradition of dipping their blow darts in the poison collected from golden poison dart frogs for hunting. The toxin on the darts could be effective for as long as a year and has therefore given these poisonous frogs their common name.

Although poison dart frogs are amphibians, they are not usually found in water as they do not have webbed toes, making them poor swimmers. Most species live on the forest floor among leaf litter, but some reside entirely up in the tree canopy and may never reach the bottom.

While the toxic frogs primarily inhabit the lower part of the forest, they mostly feed on ants, termites and other insects. Some of these insects ingest plants containing toxins that are eventually transferred to the frogs, which then process the deadly chemicals to produce the poison on their skin.

Their breeding season is mainly affected by the amount and duration of rainfall in the habitat. In a tropical rainforest where it rains a lot, they breed throughout the entire year.

For some species, the female frog first lays eggs over the leaves on the ground, providing a moist and dark environment for the male to fertilize them. As attentive parents, they then ensure that the clutches of eggs remain moist and well guarded. Once the tadpoles have hatched, the parents carry them on their backs and subsequently transport them to water sources such as ponds and bromeliads.

Some species of poison dart frogs might need to look for individual water sources for each of their hatchlings because their tadpoles may eat their own siblings. After several months in the water, the tadpoles metamorphosize, transforming into completely different creatures in body, diet and lifestyle.

The lives of poison dart frogs have been greatly threatened in recent years. In the Red List of the International Union for Conservation of Nature and Natural Resources, 17 species of the frogs are listed as "critically endangered," while many others are also "endangered" and "vulnerable".

The crux of the problem is the rapid disappearance of rainforests. Human activities, such as urban development, logging, agriculture and ranching, are leading to the destruction of the species' habitats. They are also very sensitive to small changes in their environment so climate change is a catalyzing factor for their decline in numbers.

Another major threat to them is disease. Chytrid fungus, for example, grows on their skin and suffocates them by inhibiting their water and oxygen absorption.

It is important for us to adopt lifestyle commitments that help to conserve a balanced ecosystem in rainforests.

Choose products with Forest Stewardship Council certification to encourage sustainable forest management to maintain the biodiversity in rainforests.

For a deeper understanding of the colorful species, come to the Expedition Trail in Ocean Park Hong Kong.

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