Common Toad (Bufo marinus)
Interesting Creatures…
Kaieteur News – The Cane Toad (Bufo marinus), also known as the Giant Neotropical Toad or the Common Toad, is a large, terrestrial toad native to Central and South America, but has since been introduced to various islands throughout Oceania and the Caribbean. It is a member of the subgenus Rhinella of the genus Bufo, which includes many different species of frogs found throughout Central and South America.
The cane frog is a prolific breeder; females lay single-clutch spawns with thousands of eggs. Its reproductive success is partly due to opportunistic feeding: it has a diet, unusual among Anurans, of dead and living matter.
The cane toad is very large; females are significantly longer than males, reaching an average length of 10–15 centimeters (cm) (3.9–5.9 inches). “Prinsen,” a toad kept as a pet in Sweden, is listed in the Guinness Book of Records as the largest specimen recorded. It probably weighed 2.65 kilograms (5.84 lbs) and measured 38 cm (15 in) from the snout to the vent, or 54 cm (21 in) when fully extended. Larger frogs occur in areas of lower population density. They have a life expectancy of 10 to 15 years in the wild, and can live considerably longer in captivity, with one specimen surviving for 35 years.
The cane toad starts life as an egg, which is laid as part of long strings of jelly in water. A female lays 8,000–25,000 eggs at once and the strings can extend up to 20 meters (66 ft.) In length. The black eggs have a membrane and are approximately 1.7–2.0 mm in diameter (0.067–0.079 in). The rate at which an egg evolves into a tadpole depends on the temperature: the speed of development increases with temperature.
Tadpoles usually hatch within 48 hours, but the period can range from 14 hours up to almost a week. This process usually involves thousands of tadpoles – small, black and with short tails – forming groups. It takes between 12 and 60 days for tadpoles to develop to frogs, typically four weeks. Like their adult counterparts, eggs and tadpoles are toxic to many animals.
When they emerge, toads are approximately 10–11 mm (0.39–0.43 in) long, and grow rapidly. Although the rate of growth varies by region, time of year and sex, we observed an average initial growth rate of 0.647 mm (0.0255 in) per day, followed by an average rate of 0.373 mm (0.0147 in) per day.
Growth usually slows down once the toads reach sexual maturity. This rapid growth is important for their survival – in the period between metamorphosis and in adulthood, young toads lose the toxicity that protects them as eggs and tadpoles, but are not yet developed ‘ r the parotoid glands that fully produce bufotoxin. Because they do not have this key protection, it is estimated that only 0.5 per cent of cane toads reach adulthood.
As with growth rates, the point at which the toads mature sexually varies across different regions. In New Guinea, female toads reach sexual maturity with snout-vent lengths between 70 and 80 mm (2.8 and 3.1 in), while frogs in Panama mature at 90 to 100 mm (3.5 and 3.9 in) in length .
In tropical regions, like their native habitats, breeding occurs all year round, but in subtropical areas, breeding occurs only during warmer periods coinciding with the arrival of the wet season. The cane toad is estimated to have a critical thermal maximum of 40-42 ° C (104–108 ° F) and a minimum of about 10–15 ° C (50–59 ° F). The ranges can change due to their adaptation to the local environment.
Cane Toad has a high tolerance to water loss – one study showed that some can withstand 52.6 percent loss of body water, allowing them to survive outside tropical environments. The cane toad skin is dry and warty. It has prominent ridges above the eyes, which run down the snout. Individual cane toads can be gray, yellowish, reddish-brown or olive-brown, with varying patterns. There is a large barotoid gland behind each eye. The ventral surface is cream colored and may have blotches in shades of black or brown. Pupils are horizontal and irises golden. The toes have a fleshy webbing at their bottom, and the fingers are free of webbing.
The young cane toad is much smaller than the adult cane frog at 5–10 cm (2.0–3.9 in) long. They typically have smooth, dark skin, although some specimens have a red wash. Glands do not have large adult parotoid glands, so they are usually less toxic. The tadpoles are small and uniformly black, and residents at the bottom, tend to form ladders. Tadpoles range between 10 and 25 mm (0.39 to 0.98 in) in length.
The cane toad has poison glands, and tadpoles are very poisonous to most animals when swallowed. Due to its keen appetite, the cane toad has been introduced to many Pacific and Caribbean island regions as a means of agricultural pest control.
The species derives its common name from its use against the cane beetle (Dermolepida albohirtum). Cane Toad is now considered an invasive pest and species in many of its introduced regions; of particular concern is that its poisonous skin kills many animals – native predators and vice versa – when swallowed.
Cane toads were originally used to eradicate pests of sugar cane, giving rise to their common name. However, they have many other common names, including “Giant Toad” and “Marine Toad;” the former refers to its size and the latter to the binomial name, Bufo marinus.
Most toads identify prey through movement, and sightings appear to be the main way in which the cane toad detects prey; however, the cane toad can also find food using its sense of smell. They eat a wide range of material; in addition to the usual prey of small rodents, reptiles, other amphibians, birds and a range of invertebrates, they also eat plants, dog food and household litter. Cane toads have a habit of swallowing their prey. (Source: Wikipedia)