At this spooky time of year, thoughts turn to spiders and other creepy crawlies. What better season to explore the wild world of animal toxins?
One of the superstars of poisonous animals in North America is the black widow spider. My first introduction to these legendary arachnids was while working for a summer in Arizona. The hot, dry climate is a haven for all sorts of many-legged creatures.
We were based out of a national forest campground; one of our duties was to clean the bathrooms near our sites. One evening I saw a small lizard, just a couple inches long, seemingly levitating above the floor by the bottom of a stall wall. On closer inspection, it appeared to be caught in a web. Then I saw her.
A shiny black orb about the size of a marble moved in the corner of the web. Mesmerized, I leaned in closer. I froze when I deciphered the brilliant red hourglass on the underside of the black body. The lizard hung motionless. Suddenly the spider darted over and wrapped a few strands of webbing around it, like she was creating a miniature mummy. The lizard thrashed, and the spider retreated to her corner. They repeated this dance several times, but I’ll never know the outcome, as one of my coworkers decided to interfere with the epic battle of miniature proportions and chase off the spider with a broom. I beat a hasty retreat when we couldn’t relocate the black widow.
Although the bite of these spiders is very painful, in a healthy adult human it is rarely fatal. Black widows deliver their incredibly potent venom by biting: they have two chelicerae, mouth parts with a broad base that house the venom gland and a slender fang that acts like a hypodermic needle. In female black widow spiders, the fang is about 1 millimeter long, large enough to pierce human skin. Male black widow spiders are about a quarter of the size of females and usually brownish. They have smaller chelicerae and most likely can’t breach skin. Both sexes can control the amount of venom they inject. Black widow spiders build webs in nooks and crannies and are usually content to stay there, out of humans’ way. If they do bite a person, it’s in self-defense.
Black widow venom is a neurotoxin. It takes about ten minutes to an hour for symptoms to start. You may not even feel the initial bite. The venom triggers the release of neurotransmitters, chemicals that transmit signals throughout the nervous system. These particular neurotransmitters cause constant, intense muscle contractions starting as painful muscle spasms at the site of the bite. As the venom spreads, it causes cramping of the abdominal, leg, and back muscles. It can also spark changes in heart rhythm, and generate shortness of breath, nausea, sweating, and anxiety. After 24 hours, the symptoms usually start decreasing, but can take several days to subside. Aftereffects, such as muscle spasms, tingling, and nervousness, can last weeks or even months. Medical treatment alleviates the symptoms, and may include antivenom administration if symptoms are severe.
Fortunately for Alaskans, black widow spiders can’t survive this far north. However, we do have other venomous insects — the most notorious of which are yellow jacket wasps. Unlike bees, they have a narrower waist and aren’t fuzzy. Their bee cousins feed mostly on nectar, but wasps are predators and scavengers. Yellow jackets add meat, fish, and sugary food to their menu — exactly what people bring to picnics! These social wasps are beneficial, however, because they prey on other insects such as beetles and flies that can cause problems for humans.
Only female wasps can sting. The stinger is a modified ovipositor, the tube through which fertile females lay eggs. In insects with stingers, a venom-producing gland is attached to the ovipositor, which acts as a syringe. A queen yellow jacket mates in the fall and overwinters. In the spring, she starts a new colony, tending to the first generation of workers — made up of infertile females — herself. Once they are grown, the workers take over the duties of finding food, caring for young and vigorously protecting the nest. They are most numerous at the end of summer.
These black and yellow wasps use their sting for hunting as well as defense. Their venom is a different chemical cocktail than in bees. (Someone allergic to bee stings may not be allergic to wasp stings, and vice versa.) The wasp venom paralyzes insect victims, storing them alive to feed to the wasp young. Yellow jackets have a stinger like a stiletto with only a hint of barbs; they can use it repeatedly without injury to themselves.
The venom itself is a mixture of enzymes (proteins that cause a chemical reaction) and histamines. Histamines dilate small blood vessels, thus making them more permeable, triggering a runny nose and watery eyes; they also cause muscle contractions of the bronchi, the main air tubes into the lungs. Several of the chemicals cause a burning pain, an immediate warning to leave the yellow jacket nest alone. For most people, the sting is locally painful at first, then fades. A small number of people are allergic to the venom and may have a reaction, sometimes severe, throughout the body. Instead of building an allergy immunity, an initial sting generates sensitivity to the venom. Lesser symptoms such as hives, dizziness, nausea, and itching could indicate you are allergic and have become sensitized, so could have a stronger reaction to future stings.
Last but not least, the rough-skinned newt, an easily-overlooked creature of Southeast Alaska, deserves mention. It’s a member of the most poisonous branch of the newt family. This amphibian lives along the West Coast, with its northern limit around Juneau. Rough-skinned newts are about four inches long. Their drab brown, pebbly skin above is offset by flashy yellow-orange on the belly. When threatened, a rough-skinned newt raises head and tail, revealing the bright warning color. The newts are common, living under rocks and logs or in ponds or slow-moving streams. Like frogs, they lay eggs and spend the first stage of their life in water.
Unlike spiders and insects that inject poison, the newt secretes poison over its skin. The poison is tetrodotoxin, the same neurotoxin found in the puffer fish of fugu infamy. It is 100 times as deadly as black widow spider venom. Ingesting a dose the size of a pinhead can kill an adult human. The neurotoxin works by blocking the movement of sodium ions, which carry signals between nerves. A high enough dosage causes paralysis and even death. The only animal that can survive eating a rough-skinned newt is the common garter snake (which doesn’t live in Alaska). This species has developed resistance to the poison. Although the snake may be immobilized for hours after swallowing a newt, it recovers.
In an odd Alaska connection, Captain James Cook documented the first case of tetrodotoxin poisoning. His sailors ate a local tropical fish and fed the scraps to the pigs kept on board. Many of the sailors experienced numbness and shortness of breath. None of the pigs survived. The toxin wasn’t isolated until 1909 by a Japanese scientist named Dr. Yoshizumi Tahara. In addition to puffer fish, the newts share this toxin with other heavies of poisonous animal fame, including the blue-ringed octopus. In the octopus, the toxin is produced by bacteria. It’s uncertain if this is true for the newts as well.
Luckily, rough-skinned newt’s poison must enter the digestive system or blood stream, not just touch skin, for it to cause a severe reaction. If you do handle them, wash your hands as soon as possible. Tetrodotoxin is water soluble and washes away easily. If you have any serious cuts on your hands, however, save your close encounter with a rough-skinned newt for another day!
• Beth Peluso is a freelance writer, illustrator, and avid birder. She enjoys spying on wildlife around Alaska.