Many, though not all animals, that are poisonous are also very brightly coloured. This is nature’s way of warning others away since there is no point in being poisonous if they have to take a bite out of you to find out. Some non-toxic animals mimic the colours of poisonous animals as a mechanism to avoid predation as well.
Poisonous vs. Venomous
There is actually a difference between being poisonous and being venomous. The latter are animals that inject their poison into their prey through fangs, claws or a stinger. Poisonous animals have secretions or parts of their body that are poisonous to anything that touches or eats them. They tend to use it more defensively whereas venomous animals tend to use it to capture prey although it can also be used in defense situations too.
The most well known venomous animals are probably snakes. There are poisonous snakes on most continents in the world with Australia have more than its fair share. The most land poisonous snake in the world is Australia’s Inland Taipan. It can inject enough poison to kill 100 people in a single bite, making it 400 times more venomous than a common cobra. Thankfully, it is a fairly shy animal that tends to avoid confrontation. The Black Mamba is a different story, often reacting aggressively with more than sufficient poison to kill someone unless antivenin is received in time.
Snakes are certainly not the only venomous animals though. Many invertebrates including spiders, scorpions, millipedes, centipedes, jellyfish, octopi, and even snails are quite capable of delivering a significant, and sometimes deadly, amount of toxin. The cone snail has a harpoon like projection that it uses to capture and kill prey. Needless to say, people are not common snail prey however, if you pick one up and get stung it can be deadly. The box jellyfish has been responsible for thousands of deaths over the years.
Few mammals are venomous. The duck-billed platypus is one of the exceptions, and yes, it too lives in Australia. The platypus male has large spurs on his legs. Although his toxin is not deadly to humans, it can kill many other species.
The most poisonous vertebrate is the poison dart frog. The secretions on his skin are capable of killing 10 people. That doesn’t sound like much until you realize he is all of two inches long. Two micrograms of the toxin is sufficient to kill an adult person. The second most poisonous vertebrate is the puffer fish. For reasons which elude more sensible people, some people consider eating puffer fish a delicacy. Improperly prepared, it is a deadly delicacy with no known cure.
There are a number of vertebrates with mild poisons that are likely to do nothing worse than make you ill if you come into contact with them. These include many species of fish and a few bird species. Many invertebrates are poisonous. This is a very common way to avoid predation in both larval and adult insects, particularly among butterflies and moths.
Many completely unrelated species have developed mechanisms to either inject their prey with poison or have developed poisonous aspects to their physiology to reduce the risk of predation. Some of these mechanisms are more than capable of killing a person.
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