What is a Diatom, Diatoms Online

What is a Diatom?

What is a diatom and why are they important?
A diatom is a photosynthetic, single celled organism which means they manufacture their own food in the same way plants do. They are a major group of algae and form one of the most common forms of phytoplankton and join the myriad of organisms that drift on currents in the upper layers of the ocean and lakes.

Diatoms live any and everywhere. They are found in rivers, oceans, lakes, bogs, damp rock surfaces, even on the surface of a whale’s skin -in short anywhere there is water.

Diatoms are important as they:
• provide the basis of the food chain for both marine and freshwater micro-organisms and animal larvae
• are a major source of atmospheric oxygen responsible for 20-30% of all carbon fixation on the planet
• can act as environmental indictors of climate change
• form the basis of some household goods such as pest/mite prevention and mild abrasive

Diatoms have precise ecological requirements, so they can also be sued as environmental indicators, telling us what is happening in the environment. The cell walls of diatoms may be preserved for long periods of time in sediments and provide a record of past changes in lake systems.

Key Diatom characteristics/behaviours/features:

Diatoms are the most common organism in plankton and come in an incredible array of shapes and sizes.

Diatoms have cell walls made of silica, Each species has a distinct pattern of tiny holes in the cell wall (frustule) through which they absorb nutrients and get rid of waste. Viewed under microscopes, diatoms show a huge variety of shapes with many interesting and beautiful patterns. Their shapes and structure are usually highly regular and symmetrical, and these features are used to identify and classify them.

Phytoplankton are the smallest of all plankters ranging from around 1mm to as small as 7.5 micrometres making them mostly invisible to the naked eye.

All diatoms have a siliceous (glassy) exoskeleton of two halves that fit inside one another perfectly.

Plankton means wandering in Greek and many diatoms remains as isolated cells and spend their whole lives adrift whilst others forms chains/clumps.

Copepods (small crustaceans) eat phytoplankton.

Plankton samples used to be stored in formalin which made them look grey and lifeless –a big contrast to their true colourful selves when they are fresh.


What Do Manatees Eat?

  • M.S., Resource Administration and Management, University of New Hampshire
  • B.S., Natural Resources, Cornell University

Manatees are herbivorous, meaning they feed on plants. Manatees and dugongs are the only plant-eating marine mammals. They forage for about 7 hours a day, eating 7-15% of their body weight. This would be about 150 pounds of food a day for the average, 1,000-pound manatee.

Manatees can eat both freshwater and saltwater (marine) plants. Some plants they eat include:

Saltwater Plants:

  • Seagrasses
  • Marine algae
  • Manatee grass
  • Sea clover
  • Shoal grass
  • Turtle grass
  • Widgeon grass

Freshwater Plants:

  • Alligator weed
  • Floating hyacinth
  • Hydrilla
  • Musk grass
  • Pickerelweed
  • Water lettuce
  • Water celery

Interestingly, it appears that the rostrum of each species of manatee is positioned to take advantage of the location of their preferred plants in the water column. Basically this means that the snout of each species of manatee is well adapted to easily eating the types of plants found in its particular range.


What Do Termites Look Like?

How to Recognize these Pests and the Damage they Cause

David Wrobel/Visuals Unlimited, Inc./Getty Images

  • B.A., Political Science, Rutgers University

Most of the 2,200 or so species of termites live in the tropics and have been munching away on wood for more than 250 million years—long before human being began building their homes with lumber.

Termites recycle wood products into the soil by feeding on cellulose—the main cell wall component of plants—and breaking it down. Most termite damage is caused by subterranean (underground) termites, members of the family Rhinotermitidae. Among these ground-dwelling termites, the most common structural pests are the eastern, western, and Formosan subterranean termites, who will happily eat the framing of your house starting at the bottom, where moisture has made the wood soft and working their way up.

Other termites that cause structural damage include the drywood termites (Kalotermitidae) and the damp-wood termites (Termopsidae). Drywood termites enter at the roofline, while damp-wood termites prefer basements, bathrooms, and other locations where water leaks are likely to occur. If you suspect you have a termite problem, your first step is to confirm that the pests are, indeed, termites. So what do termites look like?

Termites or Ants?

Winged ants look quite similar to termites and as a result, quite a few people confuse the two. Here’s how to tell them apart:

  • Both winged ants and termites have antennae but while termite antennae are straight, the antennae of ants are bent.
  • Termites have wide waists, while ants have narrow waists that make them look almost like bees.
  • Both flying ants and termites have two pairs of wings but termite wings are the same size. Ant wings are larger in front and smaller in the back.
  • Swarming termites range from about 1/4-inch long to 3/8- inch long which is roughly the same same size as a carpenter ant or a large fire ant. Fire ants are 1/8-inch to 1/4-inch long. Damp-wood and drywood termites are larger than subterranean termites.
  • Some worker termites are translucent, almost clear in color; others are brown or gray.
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Eastern Subterranean Termites

The termites pictured here are soldiers of the native eastern subterranean termite species. Swarmers are about 3/8-inch long. Notice their rectangular-shaped heads, which can help you distinguish them from other termites. Eastern subterranean termite soldiers also have powerful mandibles (brown jaws protruding from their heads) with which they defend their colonies.

Eastern subterranean termites live in moist, dark places. They feed on structural wood, eating out the core of beams and leaving thin shells behind. As a result, these termites can be hard to detect and by the time many homeowners notice an infestation, the damage has been done.

Formosan Termites

This Formosan subterranean termite soldier measures about 1/2-inch long. Its head is darker and oval in shape, it has a rounded abdomen, a thick waist, straight antennae, and no eyes. Like the eastern subterranean soldiers, Formosan soldiers have powerful jaws to defend their colonies.

Formosan termites were spread by marine commerce and as one of the most destructive termite species in the United States, now cause millions of dollars of structural damage in the southeastern United States, California, and Hawaii each year. They can multiply and destroy wood structures faster than other native subterranean species. They don’t actually eat faster than other termites but their nests are enormous and can contain millions of termites.

Drywood Termites

Drywood termites live in smaller colonies than their subterranean cousins. They nest and feed in dry, sound wood, making them a significant pest of wood-frame homes. Like most termites, drywood termites eat structural wood from the inside out, leaving a brittle shell. Unlike some other types of termites, however, they don’t need access to damp conditions. Many species of drywood termites live in the southern half of the United States, with a range extending from California to North Carolina and southward. Most are 1/4- to 3/8-inches long.

One way to distinguish drywood termites from subterranean termites is to examine their waste. Drywood termites produce dry fecal pellets which they expel from their nests through small holes in the wood. Subterranean termite feces is liquid.

Eastern Winged Termites

The reproductive termites, called alates, look quite different from workers or soldiers. Reproductives have one pair of wings of almost equal length, which lie flat against the termite’s back when it’s at rest. Their bodies are darker in color than soldiers or workers, and alates do have functional compound eyes.

You can distinguish reproductive termites from reproductive ants, which also have wings, by looking at their bodies. Termite alates have the characteristic straight antennae, rounded abdomens, and thick waists, while ants, in contrast, have markedly elbowed antennae, pronounced waistlines, and slightly pointed abdomens.

Eastern subterranean termites usually swarm during the daytime, between the months of February and April. Winged queens and kings emerge en masse, ready to mate and start new colonies. Their bodies are dark brown or black. If you find groups of winged termites inside your home, you probably already have a termite infestation.

Formosian Winged Termites

Unlike native subterranean termites that swarm during the day, Formosan termites typically swarm from dusk until midnight. They also swarm later in the season than most other termites, usually between April and June.

If you compare Formosan alates to the eastern subterranean reproductives from the previous image, you’ll notice the Formosan termites are a lighter color. They have yellowish-brown bodies and wings that are a smoky color. Formosan termites are also noticeably larger than native termites.

Termite Queens

China Photos/Getty Images

The termite queen looks quite different from the workers or soldiers. In fact, with her expansive stomach full of eggs, she barely resembles an insect at all. Termite queens have a physogastric stomach. This internal membrane expands as she ages and her egg-laying capacity increases. Depending on the species of termite, the queen may lay hundreds or sometimes thousands of eggs per day. Termite queens live extraordinarily long lives. A lifespan of 15 to 30 years—or more—is not uncommon.

Termite Damage

Termites can do extensive damage inside walls and floors—often without detection. Since termites eat wood from the inside out, you probably won’t find them until your home is infested, and you’re more likely to see signs of damage than the bugs themselves. Look for:

  • Sawdust or sand-like material near windows and door frames, which could be droppings of dry wood termites. You may also notice tiny holes where sawdust has accumulated.
  • Mud tubes are structures that subterranean termites build to connect the nest to the source of wood. Check outdoors and indoors at the base of your home where the frame connects to the foundation and scan your crawlspace or basement if you have one, for the brown, branching structures. They can also hang from joists, so check the floor beams as well.
  • Look for accumulations of dry fecal pellets left behind by drywood termites.
  • Shed wings from the swarmer termites or the bugs themselves can often be found near windows or windowsills. Swarmers are attracted to light so check under outdoor fixtures.
  • Does wood framing sound hollow when you tap it? You might have termites.
  • Do you have wood that looks water-damaged but it hasn’t been exposed to water? You might have termites.
  • If your painted or varnished wood or drywall is blistering, you might have termites.
  • If you notice damage across the wood grain, you might have termites.
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Termite Prevention, Mitigation, and Control

If you live in areas where termite infestations are common, it’s important to inspect your home (or have it inspected by a professional) regularly for possible infestation. Catching termites early can save you costly home repairs. Should you find signs of termites, you can treat the infestation yourself or call local pest control professionals. If you choose to do it yourself, you’ll need to find the location where they’re feeding (the «termite gallery») and aggressively treat the site with insecticide. You’ll also need to place baiting stations or treat the soil to kill the remaining insects outside.

Of course, it’s better to prevent a termite infestation than it is to have to deal with one. Prevention methods include digging a trench and spraying an insecticide into the ground to repel them. It’s a labor-intensive process but can last for five to 10 years if left undisturbed. Bait stations aren’t labor intensive but must be checked every few months. They need to be dug down 8 to 10 inches and placed at intervals of eight to 10 feet. Bait stations are first loaded with «prebait.» Once termite activity is confirmed, they’re reloaded with poisonous bait. Termites bring this poisoned bait back to their nest and it kills the colony.


Depending on Clean Water: Five Freshwater Animals

Learn about five species that live in or near freshwater

While about 70% of the Earth is covered in water, only 3% of that is freshwater. Found in glaciers, lakes, reservoirs, rivers, ponds streams, wetlands and in the ground, fresh water is essential to life. More than 100,000 species rely on freshwater ecosystems, which make up less than 0.01% of the planet’s total surface area.

WWF understands the importance of clean and healthy freshwater ecosystems for a thriving planet. We promote private sector stewardship of the valuable resource and engage with individual businesses to reduce the impacts of their water use. We also help conserve these habitats for the species that call them home.

So who are these animals that live in and around freshwater? Take a look at five such species:

Amazon river dolphin / Bouto (Inia geoffrensis) Endemic to Amazon & Orinocco Rivers South-America

1. Amazon River Dolphin
Amazon River Dolphins—also known as pink river dolphins or botos—swim in the freshwaters of the Amazon and Orinoco river basins. But their populations are decreasing as natural freshwater rivers become polluted and altered by dams. WWF conducts river dolphin surveys to determine their status, and researches the impact of dams on their populations.

2. Freshwater Turtle
Freshwater turtles are among the oldest of all living reptiles and have evolved little in the 200 million years they have lived on Earth. Slowly but surely, these ancient creatures will edge towards extinction unless action is taken to address illegal trade and ensure adequate protection is in place. While particular subspecies are impacted by wildlife trade, some experience local die-offs due to habitat destruction and the use of pesticides. WWF works at local, national and international levels to minimize the impacts of development and reduce pollution.

3. Snow Leopard
The high mountains of Asia is home to elusive and magnificent snow leopards. Their fragile habitat is also the birth place of Asia’s most important rivers, bringing life and prosperity to millions. In 2013, WWF played an important role in securing the landmark 12-nation Bishkek Declaration on Snow Leopard Conservation that will include strategies like climate change adaptation measures, limiting changes in land use and implementing flood control programs.

4. Humans
It’s not news that humans depend on freshwater for survival. But more than one billion people lack access to clean water, and 2.4 billion don’t have adequate sanitation. This puts people at risk for diseases that are often deadly. By 2025, two-thirds of the world’s population may face water shortages. And ecosystems around the world will suffer even more. WWF works with partners to advance the science of water conservation. We also work with governments, businesses and local communities to ensure that there are sufficient in-stream flows for people and other freshwater species, and promote methods for sustainable water use.

5. Mekong Giant Freshwater Fish
The world’s biggest freshwater fish lives in the Mekong River. Some reach 16 feet in length and more than half a ton in weight. Now their populations are plummeting as infrastructure development like dams block migration routes and isolate populations. WWF aims to ensure that environmental and social impacts are taken into account in the development of hydropower infrastructure on the Mekong. We also support research and monitoring, including the release of captive-bred adult specimens into the wild.

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Information About Crayfish Habitat, Along With Some Fun Facts

Crayfish are freshwater crustaceans that are used for many purposes, which includes keeping them as pets. This article provides information on crayfish habitat, and some interesting facts about crayfish as well.

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Crayfish are freshwater crustaceans that are used for many purposes, which includes keeping them as pets. This article provides information on crayfish habitat, and some interesting facts about crayfish as well.

Crayfish are the small lobster-like crustaceans that are found in freshwater bodies. Also known as crawfish and crawdads, these creatures are close relatives of the larger marine lobsters. Indeed, there is considerable physical resemblance between lobsters and crayfish, with the latter being much smaller in size than the former. Although most crayfish are found in freshwater, sometimes they can also be found in brackish water bodies and creeks (from where they might migrate further into salt water). Crayfish belong to the biological order Decapoda, and are also related to crabs, hermit crabs, and shrimp, besides lobsters.

Habitat Details

Mostly, crayfish reside in fresh water, especially where the water is running, such as rivers, streams, and brooks. They prefer running water as most of them cannot survive in polluted water. Stagnant or standing water bodies are most prone to getting dirty and polluted as they do not have access to cleaner water sources which can flow in and wash away polluted, stale water through aquatic outflows.

However, certain crayfish species such as the Procambarus klarkii are more resilient and are even able to survive in a somewhat polluted aquatic environment. Crayfish fall into three different families, out of which two are found in the Northern hemisphere and one in the Southern hemisphere. The Parastacoidea family, Parastachidae, is found in Australia, Madagascar, and South America in the Southern hemisphere, and the Astacoidea family consisting of the Astacidae and Cambaridae are found in the western part of the Eurasian continental landmass and the western part of North America respectively.

Australia is host to about 100 species of crayfish including marron, red-claw crayfish, yabby, Tasmanian giant freshwater crayfish, and western yabby. Madagascar, as a geographically significant crayfish habitat, is home to seven species falling under the genus Astacoides. Seven crayfish species belonging to the genera Astacus and Austropotamobius are found in Europe while seven species belonging to the genus Cambaroides are native to Japan.

North America comes out as the geographical habitat of the maximum species of crayfish, with a whopping 330 species belonging to nine different genera of the Cambaridae family, residing in the waters of the southeastern parts of North America. Crayfish mostly rest underneath rocks, among submerged logs and twigs, and remain hidden among other aquatic vegetation such as weeds or grass.

Amusing Facts

  • Crayfish are quite ancient creatures in the chronology of the evolution of various life forms on Earth. The oldest fossil records of crayfish have been found in Australia, which are believed to be about 115 million years old.
  • The water mold Aphanomyces astaci is responsible for crayfish plague, a disease from which they suffer.
  • Being omnivorous, the diet of crayfish includes animal as well as plant matter – both living and dead. When in their natural habitat, crayfish mostly feed on decomposing animal matter or decayed leaves as these are easy for them to rip off with their claws. In confinement, small fish like minnows and guppies, snails, algae, etc., can be included in their feeding menu. They also eat any bacteria that may grow in the tank, thereby preventing the water from getting contaminated. That’s good news for fish tank owners who have recently taken up crayfish care.
  • Crayfish tail meat is used as a bait for channel catfish, pike, largemouth bass, and muskellunge.
  • They are popular as a gustatory treat all over the world, the most consumption happening in regions like Scandinavia, Spain, France, China, United States, Mexico, and Nigeria.
  • Their natural predators include turtles, otters, wading birds, and bigger fish.
  • As a food item, crayfish have a significant calorific value and high sodium and protein content. They also have almost no fats and zero carbohydrates.

The exoskeleton of crayfish constitutes a major portion of their body mass. Hence, when you eat one, you get very little flesh and a lot of shell, making the eating effort quite demanding. This is one reason why many people do not like to order crustaceans and related seafood. However, most people who have tasted this culinary delicacy vouch for its gustatory delight.


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