Cane Toad (Rhinella marina)

Detailed introduction

The cane toad ( Rhinella marina , formerly Bufo marinus ) is a large, robust toad belonging to the family Bufonidae . Native to the tropical and subtropical regions of Central and South America, it was introduced to Australia, the Caribbean, and many Pacific islands for biological control of agricultural pests, but unexpectedly became a highly destructive invasive species .

Classification and nomenclature

• Chinese name: Cane toad, Sea toad (one of the old translations)

• English name: Cane Toad, Giant Toad, Marine Toad

• Scientific name: Rhinella marina (former name Bufo marinus )

• Family and Genus: Bufonidae → Rhinella

Appearance and Identification Features

The cane toad is one of the most famous and relatively large toads in the world.

• Size: Adults are generally about 10-15 cm long, with large females exceeding 20 cm; their weight is mostly several hundred grams, with large individuals approaching 1 kilogram;

• Body shape: The body is stout, the head is wide and flat, and the limbs are strong but relatively short, giving an overall impression of being "sturdy and clumsy".

• Skin: The skin on the back is rough, with many warts and bumps, exhibiting a typical "toad bump" texture;

• Body color: The back is mostly brown, yellowish-brown, olive or grayish-brown, often with irregular dark spots or cloud patterns, while the belly is lighter, which is cream, grayish-white or with a few spots;

• Parotid glands: There is a pair of very well-developed parotid glands (parotid glands, venom glands) behind the eyes, which are shaped like raised strips and can secrete milky white venom when threatened;

• Sexual differences: Female toads are usually larger, while male toads have stronger forelimbs and well-developed mating pads during the breeding season.

A robust body, large venom glands behind the ears, and rough, warty skin are key features for identifying the sugarcane toad in the wild.

Distribution range and habitat

The cane toad is native to tropical and subtropical regions of the Americas .

• From southern Mexico, Central America, all the way to the Amazon basin and parts of Brazil;

• Natural habitats include lowland rainforests, savannas, wetland edges, and river valleys.

Due to its artificial introduction, it is now widely found in:

• Caribbean islands and parts of the Pacific Islands;

• It is found in large areas of northern and eastern Australia, both along the coast and inland.

• Some sugarcane growing areas and surrounding tropical farmlands.

The sugarcane toad is highly adaptable and can utilize a variety of habitats:

• Farmland, sugarcane fields, and pastures;

• Urban lawns, parks, gardens, and artificial waterways;

• The edges of ponds, ditches, drainage ditches, and the perimeter of wetlands.

Given a relatively warm climate, ample insect resources, and nearby water bodies for reproduction, they can quickly establish populations.

Lifestyle and Diet

Sugarcane toads are primarily nocturnal and terrestrial .

• During the day, they mostly hide under rocks, among tree roots, in caves, or in shady places under man-made structures;

• They come out at dusk and night, walking slowly on the ground or jumping short distances.

• They often freeze temporarily when exposed to strong light, and are easily "frozen" by car headlights or human flashlights.

It has a very wide range of diets and is a typical opportunistic omnivorous predator .

• Various ground insects (beetles, crickets, cockroaches, ants, moths, etc.);

• Spiders, centipedes, and other arthropods;

• Earthworms, mollusks, and even small amphibians and reptiles;

• In artificial environments, they may also consume pet food, garbage scraps, etc.

This habit of "eating a little bit of everything" is one of the important reasons for its successful spread in the invaded areas.

Toxicity and Defense

The most striking feature of the sugarcane toad is its potent venom :

• The milky white, viscous venom secreted by the parotid glands and skin glands contains various bufotoxins and cardiac glycosides .

• It is highly toxic, even deadly, to many predators, such as dogs, cats, small carnivorous mammals, reptiles, and fish.

• Tadpoles and eggs are also poisonous, and fish or amphibians that prey on tadpoles may also be poisoned.

Contact with its venom can cause irritation to the eyes, mouth, and skin in humans; ingestion or large amounts of the venom poses a potential serious risk of cardiotoxicity. In areas where it has been introduced, cases of pet dogs dying from poisoning after accidentally biting cane toads are not uncommon.

Reproductive capacity

The sugarcane toad's extremely high reproductive rate is key to its successful invasion.

• Breeding usually occurs during the rainy season or after continuous rainfall;

• A female toad can lay thousands or even tens of thousands of eggs at a time, which are arranged in long, gelatinous strings and attached to aquatic plants or objects in the water.

• Tadpoles live in groups in the water. They are small in size and dark in color. Their development speed is greatly affected by water temperature and food.

• Once the larvae mature into baby toads, they can begin to live independently on land.

High spawning capacity, extensive water utilization capabilities, and strong environmental tolerance enable their populations to expand rapidly in suitable areas.

Invasion of ecosystems

In its native habitat, the cane toad is part of the local ecosystem; however, in introduced regions such as Australia, it has caused serious impacts on native species.

• Its potent toxicity has caused local predators (such as monitor lizards, snakes, and wild dogs) to die from poisoning after consuming it;

• They compete with native frogs and toads for habitat and food resources;

• It alters the local food web structure and energy flow patterns.

Therefore, the sugarcane toad is considered a harmful invasive species in many areas, and related management includes controlling its spread, removing egg masses and larvae, and promoting pet protection.

Preserve the status quo

On a global scale, the sugarcane toad is classified as Least Concern (LC) on the International Union for Conservation of Nature (IUCN) Red List, indicating that its population is very large, stable, and even expanding.

However, this "Least Concern" status is based on its excessive success and widespread distribution , and does not mean that it is "worthy of protection" in all regions. In countries and regions where it is an invasive species, the management goal is instead to limit and control its numbers in order to protect native ecosystems.