I have always been fascinated by poisonous plants. I write murder mysteries, and what better murder weapon than a toxin from a naturally occurring plant? We have several poisonous plants here on Kodiak Island, and over the next few weeks, I will describe a few of them.
In the summer, most of Kodiak Island is covered by a dense jungle-like growth. We have beautiful wildflowers and plants bearing delicious berries, including salmonberries, blueberries, raspberries, cranberries, crowberries, watermelon berries, and others. Rhubarb and raspberries planted by early settlers remain abundant in some areas.
There are a few plants here, though, that are not so innocent. The sap and outer hairs of cow parsnip, locally called pushki and one of the most prolific plants on the island, contains the chemical furanocoumarin which causes an extreme sensitivity to light. If a person comes into contact with the sap of a cow parsnip plant, within a few days, he will likely develop a red, itchy rash and blisters on the area the sap touched. These blistering sores last for days or weeks. I often use a weed eater to clear vegetation around the house, and I’ve learned the hard way not to cut cow parsnip with a weed eater because when the sap flies from the plant and splatters my hands and face, I know I will have painful, ugly, red welts in a few days. Some people are not allergic to cow parsnip, and others are so allergic they will react if they merely touch the stems or leaves of the plant.
Nettles are another troublesome plant on Kodiak. Fine, stinging hairs cover the leaves of a nettle. Some researchers believe formic acid causes the hairs to sting, while others attribute the sting to a histamine compound. If you touch the leaves of a mature plant, you will feel a prick, much like a wasp’s sting. The pain may last for a few hours but will eventually subside. Nettles lose their sting when cooked and taste delicious, much like spinach. Nettles also have many medicinal applications and may be used to ease sore muscles and joint inflammation
While these plants can be irritating and painful and make walking through the dense vegetation on Kodiak a challenge, neither cow parsnip nor nettles will kill a human. Over the next few weeks, I will cover the deadly toxic plants we have in our area and give accounts of cases where they have been used both in literature and in the real world.
I mentioned last week in my post about sea stars that beaches on Kodiak teem with an abundant variety of brightly colored sea stars. Sadly, though, sea stars are not as abundant here as they were a few years ago. I took a walk on the beach yesterday and was alarmed by how few sea stars I saw. Those I did see looked healthy, but the vast majority were wiped out by a deadly virus.
In June 2013, sea stars along the Pacific coast of the United States began dying in large numbers. Die-offs of sea stars have occurred before in the 1970s, 80s, and 90s but never of this magnitude. Within just three years, millions of sea stars from California to Alaska died from a disease called sea star wasting syndrome (SSWS). Sea stars with SSWS develop white lesions in the ectoderm quickly followed by decay of tissue surrounding the lesions which leads to fragmentation of the body and death. Biologists estimated 95% of some sea star populations were decimated by SSWS. While most species of sea stars were affected by SSWS, ochre stars (Pisaster ochraceus) and sunflower stars (Pycnopodia helianthoides) were especially hard hit.
The syndrome was first noticed in ochre stars in June 2013 along the coast of Washington state. In August 2013, divers reported a massive die-off of sunflower stars just north of Vancouver, British Columbia. In October and November 2013, large numbers of dead sea stars were noted in Monterrey, California, and by mid-December, SSWS had reached southern California. In the summer of 2014, the disease had spread to Mexico and parts of Oregon. SSWS was first reported in Alaska in Kachemak Bay in 2014, but it wasn’t until 2015 and 2016 that sea stars began dying in large numbers in Alaska.
Biologists are certain sea stars are dying from a virus, but when they isolated the virus, they realized this virus was present in preserved museum samples taken from as far back in the 1940s. They believe some other factor such as increased water temperature or a change in pH is stressing seas stars and allowing an otherwise dormant virus to rage through their populations. Researchers noted an increase in ocean water temperature preceded the outbreak of SSWS, and in areas where the water temperature rose the most, the disease was more widespread. To test the theory that increased water temperature played a big role in the breakout of the disease, scientists placed sea stars in aquarium tanks ranging in temperature from 54 degrees to 66 degrees Fahrenheit. The results were clear, the hotter the tank, the more quickly the sea stars succumbed to wasting.
The drastic reduction in sea star populations is evident on Kodiak Island, and biologists worry how the loss of sea stars will affect the intertidal community. Sea stars are considered a keystone species, important to maintaining diversity in the marine environment. Sea stars eat mussels and sea urchins whose numbers could now explode and decrease biodiversity in intertidal and subtidal communities.
Scientists consider the recent outbreak of SSWS the single largest, most geographically widespread disease ever recorded, and as ocean temperatures keep rising, they fear the outbreak of the disease will continue.
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Visitors to our lodge are often surprised by the large number of brightly colored sea stars inhabiting the low-tide zone on Kodiak Island. Sea stars are prolific throughout the Pacific Northwest and are critical to the health of intertidal and subtidal communities. Scientists have identified more than 120 species of sea stars in Alaska, including the sunflower sea star, one of the largest sea stars in the world.
Sea stars are often called starfish, but since they aren’t fish, biologists prefer the name sea star. Sea stars belong to the phylum Echinodermata. Other echinoderms include sea cucumbers, sea urchins, sand dollars, and brittle stars. Echinoderms usually have pentamerous radial symmetry, meaning the body can be divided into five parts around a central axis. This five-parted symmetry is easy to see in a sea star with five arms, but it is also apparent if you look at the bottom of a sand dollar or the pen of a sea urchin. Some sea stars have more than five arms. A sunflower sea star has twenty arms, but the animal is still divided into five equal parts around the central disk.
Sea Stars are flattened in appearance and may range in size from 1 inch (2.54 cm) to over a yard (1 meter) in width. A sea star has an internal skeleton which is somewhat flexible. The skeleton consists of small calcareous plates bound together with connective tissue. Sea stars may look rigid and sedentary, but the connective tissue between the plates allows them to bend to attack prey, flee predators, and right themselves when they are turned upside down.
A sea star’s anus is in the center of the top side, or the aboral surface of the animal. A circular madreporite is located just off center on the aboral surface, and this madreporite is a critical part of the circulation system of the sea star. Instead of a circulatory system, a sea star has a water vascular system, and the madreporite acts as a trap door through which water can move in and out in a controlled manner. The mouth of a sea star is located in the center of its underneath or oral surface. Open furrows containing tube feet extend from the mouth along the length of each leg.
Sea stars do not have eyes, but they have eyespots that can detect light at the tip of each arm. Interestingly, scientific studies have shown some species of sea stars move toward light while others move away from the light. Neurosensory cells which are sensitive to both touch and chemical tastes cover the surface of a sea star and are particularly dense in the suckers of the tube feet. Many species of sea stars are covered by clusters of tiny, calcareous pincers. These tiny pincers deter predators and keep the surface of the sea star free of parasites and debris. Also on the surface, thin-walled gills protrude between the calcareous plates and serve to exchange respiratory gases and excrete liquid wastes.
The internal anatomy of a sea star includes the water vascular system, digestive tract, reproductive organs, and nervous system. The water vascular system uses muscles and hydraulics to power a sea star’s tube feet. The tube feet not only allow a sea star to move but are used to grasp prey, and the combined force of numerous tube feet is strong enough to pry apart a clam shell. Most seas stars move very slowly, and their pace is measured in inches per hour, but giant sunflower sea stars can travel at a speed of two feet per minute.
The mouth of a sea star opens into two stomachs connected to paired, lobed organs called pyloric caeca. The pyloric caeca extend into each arm and aid in the digestion of food. Sea stars are either male or female, and their reproductive organs, or gonads, lie between the pyloric caeca in each arm. In the spring, sea stars broadcast either eggs or sperm through pores in their arms into the water where chance fertilization occurs. Sea stars have no brain or central nervous system, but they have a nerve ring in the central disk connected to radial nerves running the length of each arm. The radial nerves are connected to a diffuse network of nerve cells scattered throughout the skin. Sea stars have the ability to regenerate lost arms.
Sea stars utilize a range of habitats and may be found from the shoreline to depths greater than 13,450 ft. (4,100 m). Sea stars consume a wide variety of prey, including sponges, snails, clams, mussels, sea cucumbers, barnacles, anemones, scallops, fishes, and even other sea stars. Some species of sea stars feed on plankton, while other species prefer dead organisms. Sea stars have few predators and are believed to have a lifespan of only a few years.
Next week, I will post about sea star wasting syndrome, a devastating disease that has killed millions of sea stars in the last few years from California to Alaska.
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