by Rick O'Connor | Aug 28, 2015
The round body of a microscopic nematode.
Photo: University of Nebraska at Lincoln
In the first article of this series we discussed the how unpleasant the subject of worms were but how beneficial many species are to our environment. We highlighted the flatworms and this week we will look at the roundworms.
There are a variety of round-shaped worms but the term “roundworm” is usually associated with the Phylum Nematoda; and more commonly called “nematodes”. There are over 10,000 species of nematodes on our planet and they are found in all habitats from the polar region to the tropics and even in deserts. They are found in freshwater and marine systems and are quite common in soils. Within an acre of land there could be literally billions of them.
As the name suggests their bodies are round, not flat, and smooth, not segmented; which separates them from the other two groups we are writing about. Most are very small (< 2.5mm – 0.10”) but some may reach 5cm (2”). Most are carnivorous, some even consume fleas in your yard, but others graze on algae, and others detritus. Many species have a stylet (needle) they use to puncture the cell wall of their prey to consume the internal organic matter. They do not have a developed brain but they do have a series of nerves that run throughout their body. Most are connected to exterior structures associated with the sense of touch, such as setae. There are generally male and female worms in this group and the males are typically smaller in size. However hermaphroditism does exist.
As with most groups of worms, it is the parasites that we really dislike – and there are plenty of parasitic nematodes. They infest a lot of different species. Some live on the outside of plants while others live on the inside. Some are parasitic only at the adult stage, some only as a juvenile, others begin within invertebrates and move to plants as adults. They typically exit one organism through the feces and infest another when the feces is consumed by another.
The life cycle of the human hookworm.
Center for Disease Control
Many species of nematodes have a primary and secondary host life cycle, similar to the flatworms, but others complete the entire life cycle within one organism. Hookworms, a common nematode found in humans, enters the body and feeds on blood cells. The young larva live in the environment and can for a few days in good conditions. When they contact a human they penetrate the skin and move through the circulatory system to the lung. Here they burrow into the bronchioles (airway) and work themselves to the pharynx where they are swallowed by the host and eventually end in the intestine. Within the intestine they feed on blood cells within the intestinal wall. When they reproduce the eggs are released within the feces and enter the environment. If conditions within the environment are good the eggs will hatch and the cycle begins again. Pinworms and whipworms are also parasitic nematodes that infest humans.
Though we dwell on the negative aspect of the parasitic nematodes many species are used indicators of soil health and can give farmers a better idea of the condition of their soil. Suggesting to them what to plant or what they need to do to condition their soil to plant a specific crop.
Next week we will look at the most familiar of the worms – the segmented ones.
by Rick O'Connor | Aug 21, 2015
I am afraid worms are not the most pleasant topic to write about but few people know much about them. I was once told when I was a student that if you wanted to become known as a scientist study worms, no one else is.
When we hear the term “worm” negative things enter our minds: parasites, disease, uncleanliness to name a few, but many worms are actually beneficial by removing detritus (decaying organic matter) from the environment; the garbage cleaners in a sense. There are at least 10 phyla of worms but this series will focus on the three major groups; flatworms, roundworms, and segmented worms.
The human liver fluke. One of the trematod flatworms that are parasitic.
Photo: University of Pennsylvania
Flatworms include three classes and two of those are parasitic; those are the flukes and tapeworms. Most are very small and emerge in low or no light. The parasitic forms typically live in the gut but can infest other organs of their host organism. There are several species that infest humans but most are specific to a particular group of animals. The flatness of their bodies may have to do with moving materials in and out of the body. Most flatworms lack well develop organ systems so gas exchange occurs through the skin. The more the flat they are, the more surface area they have, the more gas exchange can occur. This is supported by the fact that the larger the flatworm is the more flat they are.
Tubellarians are basically non-parasitic flatworms and are mostly aquatic, many living in the marine environment. Some crawl across the seabed but others can actually swim. As with other flatworms, their digestive tract is incomplete (meaning there is only one opening – the mouth – where food comes in and waste goes out), and this mouth is located half way down their body on the ventral side. Most of these flatworms are carnivorous feeding on small invertebrates and dead organisms. They do have “eyespots” which do not form images but can detect light. Most flatworms are what we call “negatively phototaxic” meaning they sense light but do not like it and will burrow or hide when the sun rises.
Trematoda are what we call flukes and are parasitic. Most are only a few centimeters long but some can reach a meter (3ft.) or more! Flukes have a protective covering on their skin to protect them from the enzymes of their host’s internal environment. Their life cycle requires a second host, meaning that the adult lives in one type of animal but the larval stage occurs in another. Adult flukes live in vertebrates (typically fish), and the secondary hosts are usually invertebrates (typically snails). The eggs (cyst) produced by the adults leave the host organism through their feces. Once in the environment the secondary host consumes them where the larva develop. Eventually the secondary host is consumed by the primary host (fish) where the larva develop into an adult and the cycle begins again. They typically infest the gut but can infest other organs as well.
A tapeworm actually has a round head which posses hooks to attach to the lining of the gut.
Photo: University of Nebraska Omaha
Cestods are one of the more recognized flatworms; these are the tapeworms. Tapeworms lack a digestive tract and most absorb all of their nutrients on through their flat bodies. Like their fluke cousins, tapeworms are endoparasites but almost all of them infest the digestive tract. Like their fluke cousins they require a secondary host, usually an arthropod (insect, spider, or crustacean). With a vertebrate serving as the host organism.
Though there are flukes and tapeworms that infest humans most are found in fish and are specific to that group. The ones that do infest humans require the secondary host cycle described above and, because of sanitary conditions we live in, are not commonly found in the population. This cannot be said for parts of the world where sanitary conditions are not to our standards. As horrible as parasites sound many species of nonparasitic flatworms are beneficial by removing detritus from lakes, rivers, and bays.
Next week… Roundworms.
by Rick O'Connor | Aug 21, 2015
With great interest I read this week that the Orianne Center for Indigo Conservation in central Florida has begun a project to reintroduce the federally listed Eastern Indigo Snake (Drymarchon corais cooper) to the Florida Panhandle; where there have been no verified sightings since the late ‘90s.
The eastern indigo snake is the largest nonvenomous snake in the southeast.
Photo: Molly O’Connor
The Eastern Indigo is the largest nonvenomous snake in the southeast, reaching lengths of eight feet. They prefer sandhills and dry upland areas such longleaf pine forest. The males can patrol areas as large as 3000 acres and are associated with gopher tortoise burrows. Being large snakes they feed on a variety of animals including venomous rattlesnakes. The loss of habitat, along with the decline of gopher tortoises, triggered the decline of this species, and they are rarely seen in the western portions of the range. Indigos are most often found in southern Georgia and peninsular Florida, but sightings at these locations are not common.
The Orianne Center is currently raising young Indigos for release in the Nature Conservancy’s Apalachicola Bluffs and Ravine Preserve. They are planning to release 20 snakes there and an additional 30 in the Conecuh National Forest to support a similar project that Auburn has been doing for the last four years. These snakes are pretty easy to identify. They are iridescent black, usually having an oily sheen appearance to them, with orange coloration on the lower jaw. Oh… and they are big… 8 feet. We are hoping panhandle residents will not be alarmed if they encounter one and allow them to move along. During the last four years of Auburn’s project they have lost quite a few to cars and one visited a youth camp in the National Forest. Alarmed at first the residents soon learned that they were feeding on copperheads in the tool shed and have since loved having these snakes around.
You can read more about this project and the Orianne Center at:
http://blog.nature.org/science/2015/08/17/indigos-return-a-florida-breeding-program-raises-eastern-indigo-snakes-for-reintroduction/
by Rick O'Connor | Aug 14, 2015
Boating is a very popular activity in the sunshine state.
Photo: Rick O’Connor
Okay… Let’s start at the beginning. We began drilling oil over 100 years ago. The crude was refined into kerosene, gasoline, plastics, and other products that have completely changed our lives. A huge international industry developed from the drilling and employed who knows how many people. But then a few problems began to emerge…
The emissions from burning oil have added compounds to our atmosphere that have contributed to human health issues and have changed the climate. As the human population grew the demand for this energy source grew, and the problems grew as well. One of the first steps made by the governments and the industry to curb the problems was the removal of lead from gasoline. At first this was problematic because many of the internal combustion engines that ran on gasoline did not run efficiently on unleaded and a back-lash occurred. Service stations offered both leaded and unleaded at the pump and motorist could choose. The car industry followed by developing engines that ran on unleaded only and eventually leaded gasoline was no longer offered. Since the phase out the blood lead level has dropped from 88% of children in the United States to 1% in 2006 (www.worstpolluted.org).
The next issue was the amount of oil. Though many text list fossil fuels as a renewable energy, it takes millions of years to renew it – so in the time frame we think of it is basically a non-renewable resource. With a finite amount of oil available the industry began looking for new sources of oil and encouraging the public to conserve their use. The government answered this by requiring the car industry to produce fuel efficient automobiles, which they have. My original truck got between 8-12 mpg, today’s trucks can get over 20 mpg. Smaller, more efficient engines that burn unleaded gasoline have certainly improved some of the problems.
One of many marinas in Florida where boats fuel.
Photo: Rick O’Connor
However the population continues to grow. I remember just a few years ago everyone was amazed when we hit 6 billion humans, we are now at 7.2 billion and the clock moves quickly (http://www.census.gov/popclock/) . The largest growth has been in China and India. Both of these nations have experienced huge increases in their economy and quality of life. As their economic status improved their demand for energy increased and concerns about the amount oil demand increased. With the somewhat finite amount of oil, and the compounds that are still part of the emissions. Many became concerned about what would happen with growth in that part of the world. One answer to both emissions and amount was to begin searching for alternative fuels. Biofuels was one option. These fuels can be generated from plant material, which can produce ethanol. There are certainly some problems with growing corn for fuel instead of food but this is one option that the industry began to explore. Just as the original engines had problems with unleaded fuel, today’s engines have problems with ethanol. The engines that power the Indy and Formula 1 race cars do use biofuels but who can afford a Formula 1 engine? The industry’s response was to blend ethanol into the existing unleaded gasoline and offer this. The hope was that the global amount of gasoline could be conserved using this method. The original fuel was 10% ethanol and was called E-10 fuel. As expected problems occurred. Though the engine ran pretty efficiently if the fuel was used in a relatively quick period of time, and not allowed to sit within the tank and fuel lines, the ethanol began to degrade parts. Pieces of rubber and plastic blocked fuel lines causing all sorts of problems. I personally experienced this issue with my outboard motor. The outboard industry responded by developing more E-10 friendly engines and additives you can use if your fuel will be sitting in the tank for long periods of time. It is currently recommended that if you are not going to use your lawnmower or outboard over winter that you fill the tank for storage. Ethanol breaks down and water is produced. With a full tank there will be less water accumulation over time. Now comes E-15.
Yep… E-15, 15% ethanol. Though this move will eventually improve some of the problems with using oil there will be, as there have been, some growing pains. IT IS NOT RECOMMENDED THAT OUTBOARD MOTORS, LAWN CARE MOTORS, OR ANY OTHER SMALL ENGINE, use this E-15 fuel. It is currently being offered at service stations but in many cases is NOT clearly marked. All boaters, lawn care operators, and anyone else who uses small engines should check the gas pump labels carefully before fueling.
by Rick O'Connor | Aug 14, 2015
Most people, including myself, have been taught this. Snakes are in an unusual situation of trying to kill prey with no hands or claws. A few can inject venom, others either swallow it whole (such as an egg) or the coil around their prey “suffocating” it – or so we thought. It has been my understanding that snakes did not actually “squeeze” the air out of their prey but rather coil tighter each time the prey exhales, tighten the coils until the prey is dead due to lack of oxygen. A recent paper published in the Journal of Experimental Biology is challenging this.
The issue stems around the fact of how fast the prey die. Some biologists felt death of the prey occurred to quickly for suffocation; thus began the hunt of what was the cause. Dr. Scott Boback, of Dickinson College in Pennsylvania, looked at the possibility of cardiac arrest. He and his team developed a method of monitoring cardiac and circulatory data in rats before, during, and after an attack by a constricting snake; in this study – the common boa. Using pre-attack vitals as baseline the team compared numbers during the attack and after death; which occurred, on average, 6.5 minutes. What they found was interesting.
A constricting gray rat snake coils around a bird.
Photo: Nick Baldwin
Within six seconds of being bitten and having the body coil the peripheral arterial blood pressure dropped by half and the central venous blood pressure increased six fold. After 60 seconds the heart rate had dropped by 50%. After death, again mean time was 6.5 minutes, the peripheral arterial blood pressure and heart rate had dropped significantly and 91% of the rats (n=11) had evidence of a dysfunctional cardiac system. Blood samples were taken from the deceased rats. These samples indicated that the potassium levels had increased 2-fold and the pH and dropped from 7.4 to 7.0. Some suggest that the increased potassium levels may have been toxic enough to kill the rat.
Though this is only one study the results do suggest that the cause of death may be due to cardiac arrest and not the lack of oxygen. For many of us it is a point of “who cares… the rat is dead”. But for those of us in science education (teachers, park rangers, etc.) the results are of interest. We are being asked to explain how the scientific process works to students, visitors to parks, and to the general public. This is a good example of how science works. The process of experimentation finding results that do not always fit the “norm” of general understanding yet they do occur, generating more questions and more experimentation. Though this one study does not mean that suffocation is incorrect it does suggest there is another explanation and this, at least at this stage, is how we should explain such things to the public.
To view a copy of the article and abstract for this paper visit:
file:///C:/Users/roc1/Documents/Wildlife/nusiance%20species/Snakes/Living%20With%20Snakes/Snake%20constriction%20rapidly%20induces%20circulatory%20arrest%20in%20rats.html
http://jeb.biologists.org/content/218/14/2279.abstract
by Rick O'Connor | Aug 7, 2015
First let me explain that Seahorse Key is not in the Florida Panhandle but the story is interesting and a similar phenomena could occur here. Seahorse Key is an isolated island 3.6 miles southwest of Cedar Key in Florida’s Big Bend. There is a science lab owned and maintained by the University of Florida and Captain Kenny McCain on the island but can only reached by boat. Many forms of wildlife, particularly birds, seek out these isolate islands for nesting due to the lack of predators; and Seahorse Key is no exception. Another interesting point about this island is that it may have the highest density of cottonmouths in the state. Dr. Coleman Sheehy has been studying this population and estimates that there may be about 600 cottonmouths on the island. So what is the mystery?
Seahorse Key. An isolated island near Cedar Key
Photo: FMSEA
Well we will first look back to last year and the nesting habits of the island’s birds. In 2014 Vic Doig of the U.S. Fish and Wildlife Service had logged seven different species of egrets, herons, cormorants, pelicans, and ibis nesting on the island. The number of nest per species varied from 100 to 5,000 with the white ibis producing the highest number. Dr. Sheehy surveys the cottonmouths by walking the shoreline and counting the number of snakes he encounters; which is typically around 30. The snakes and nesting birds are concentrated near Gardiners Point. Though the cottonmouths feed on rats they seem to rely on the fish that fall from the nests above.
As 2015 began the biologists noticed something different right off the bat. Though the birds were returning they were not returning in typical numbers, particularly the white ibis. These birds normally are the most abundant nesters on the island, but not this year. Dr. Peter Frederick, University of Florida’s Department of Wildlife Ecology and Conservation, did not seemed to alarmed by this knowing that white ibis are nomadic and do not stick with the same nesting locations for more than a few years. They tend to go where the food is most abundant. No mystery here… Then it happened…
A cottonmouth consuming a fish from a birds nest.
Photo: University of Florida
Within a very short period of time, during the second week of April, all of the other birds began to leave. Researchers found the nests falling apart, no eggs or chicks within them, and hundreds of eggs on the ground. They also found the remains of 26 dead birds in the area. Where had they gone? What had happen?
Autopsied birds found no consistent cause of death. Most of the eggs on the ground had small holes indicating they were preyed upon by birds, most probably fish crows. However these birds are more opportunistic scavengers and would have fed on the eggs only after they had fallen from the nests. Researchers then discovered that many of the birds had relocated to nearby Snake Key. Though they had begun nesting there, fewer than half had done so. All seven species were found there but the number of nests had dropped from 100 – 5,000 to 50 – 600. Many of the birds were still missing. Where did they go? Better yet, why was Snake Key selected and Seahorse abandoned? And did the exodus of birds from Seahorse impact the snakes? The answer is… Yes. Dr. Sheehy’s survey found that the number of snakes encountered along the forest edge had dropped from 30 to 10. He noticed these snakes were thinner and he observed one cottonmouth consuming another, something he had not noticed before. The snakes had been impacted by the decline in nesting birds. What had happened on Seahorse Key?
One idea was put forth by Dr. Sheehy. He had noticed an increase in the number of raccoons on the island. Again, these isolated islands are selected for by nesting birds because of the lack of such predators and Dr. Harvey Lillywhite indicated that the typical number of raccoons on the island is zero. But Dr. Sheehy and Captain McCain had trapped and relocated seven raccoons earlier this summer. This suggests that a large group (large for this island) had found their way to Seahorse Key. Dr. Sheehy suggests that the cause of the movement of birds were the raccoons. There is no evidence of them attacking the birds but they believe the shear presence of the animals was enough for the birds to relocate. However Dr. Fredrick points out that (a) there was little evidence of the raccoons preying on the fallen eggs and (b) he could not find track or scat evidence of more than one or two raccoons on the island during his initial survey after the birds left. He is not so sure the raccoons were the cause.
Nesting birds on Seahorse Key
Photo: courtesy of flickr
Then there is the question… Where did the seven raccoons trapped come from? One suggestion was that they were released by locals. This was based on the fact that raccoons captured were well fed and had a mild temperament, not what you typically encounter with trapped raccoons from the wild. Later there was a confirmed report of a local who does take in orphaned raccoons, raises them, and releases them; they could have released some on Seahorse Key – but this has not been confirmed.
So right now this mystery remains unsolved. But the story does indicate the types of problems that can occur when humans relocate animals to habitats they do not typically live in. It takes years for Mother Nature to develop a balance only to have it quickly fall apart by the human release of animals we wish to move or that we think will do better in another location.
You can read more on this story at:
http://fieldguide.blogs.gainesville.com/427/amysteryatseahorsekey/
http://fieldguide.blogs.gainesville.com/450/a-mystery-at-seahorse-key-part-2/
