Be eaten behind bars

The Venus Flytrap (Dionaea) is the most spectacular of the meat eating plants. The leaves of this carnivore consist of two parts that can close. When an insect or small spider is touching the tactile hairs when eating from the nectar present on the leaf surface, the folding mechanism is activated. The two parts of the leaf will close within the blink of an eye. ‘Bars’ prevent the victim from escaping. However, the plant cannot be fooled. To be sure that the prey is present, it must touch the six tactile hairs of the leaf twice. When touched once, the leaves will not close.

Venus Flytrap

The microscopic photo shows the glands that are on the inside of the leaf. These glands secrete the fluid that serves to digest the prey

Prepared slide by Lieder

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Aeolosoma - The strangest worm in the world?

Aeolosoma is a genus of annelid worms like earthworms. But unlike earthworms, these are much smaller and can be found in different freshwater habitats like ponds and streams in many parts of the world. But it's not just in nature you are able to find these as they also inhabit almost all freshwater aquariums, and probably also a huge part of unchlorinated pools. In aquariums they are introduced with food or plants and can sometimes be found in extremely large numbers.

African mahogany Khaya ivorensis

Khaya ivorensis is the most important tree species that provides mahogany originating from Africa. This tree species can grow to a height of around 40 to 50 meters with trunks up to 2 meters thick. The basis of these trees is often buttressed. Khaya ivorensis prefers wet virgin evergreen forest. In Africa, this wood is traditionally used in canoe building. Different parts of the tree are important in traditional medicine and soap making. This noble type of wood is one of the most important species for wood plantations, because the trees grow quickly and produce high-quality wood that is often used where durability and beauty of the construction are important.

Crystals have been made explicitly visible on the photos using polarization. Crystals in plant tissues are generally waste materials and in some cases (amongst others) may also have a strengthening function.

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Amoebas - Shapeshifters of the microworld

Amoebas are free living eukaryotic organisms capable of changing their shape in order for it to move and feed. This is done by extending cellular projections called pseudopodia (see image). When the amoeba moves it uses these projections as a form of conveyor belt stretching towards the desired way of movement and the cell then fills the pseudopod with its insides called the endoplasm creating a sort of rolling movement as seen in the video below. When feeding, the organism will surround the food with its cell membrane and absorb it into its cell body where it is digested. A big part of the endoplasm is made up of these ingested particles as well as cellular organelles such as mitochondria and the nucleus containing the DNA.

Bdelloid rotifers - An entire class of animals with no males

We have previously looked at the microscopic animals called Rotifers in general, but today we are going to take a closer look at a specific class of rotifers called Bdelloidea with quite a unique way of living. Bdelloid rotifers are extremely common all over the world where they can be found in different freshwater habitats like ponds, streams, moss, and garden birdbaths where they can be found in enormous amounts from time to time. These animals are incredibly tiny with a size of only 150 - 700 microns when fully stretched. Like other rotifers they feed on microalgae, bacteria, and single celled organisms. So far they sound just like other rotifers, however they are very different in a few ways.

Some of the smallest crustaceans in the world

Crustaceans are a huge group of animals living all over the world. There are more than 67.000 known species which dramatically vary in size from around 0.1 mm to almost 4 m. Most are aquatic animals, like crabs and shrimp but some are terrestrial like the woodlouse. All crustaceans have a tough exterior called an exoskeleton used to support and protect their body. This armor is mainly made up of long polymers called chitin combined with calcium carbonate to make it hard. Here we will look at a few of the smallest crustaceans you might encounter in a water sample. The first one we take a closer look at is a copepod.

It is covered in symbiotic algae. The copepod is surrounded by 

younger individuals at different stages of development.

Image stacking - for increased depth of field

A microscope is not only useful when investigating microscopic specimens. To see the fine details of insects and other larger specimens, a microscope is also extremely handy. However, the depth of field (DOF) is very shallow and only a small portion of the specimen can be in focus at each time. This is not due to bad objectives or microscope, but due to the high magnification. But this problem can easily be overcome by the use of an image processing method called focus stacking.

Illustration of the shallow depth of field.
The focus plane is at the top of the right eye and mouth

Haematococcus pluvialis - The red colored green alga

Haematococcus pluvialis is a single celled green freshwater alga found all over the world. Each cell is encased in a transparent capsule and varies in size from 10-50 microns depending on its life cycle stage, but most are around 20 microns. H. pluvialis can be found in two major stages, active and inactive. In the active stage the algae are motile and move with two long whip-like projections called flagella. In the inactive stage the cells become non-motile encased cysts which are able to tolerate periods without water and huge temperature fluctuations. One of the protective strategies the algae use during the non-motile stage is the production of a molecule called astaxanthin.

Red blood cells - the cells that help you breath

Adult humans carry around 5 liters of blood in their circulatory system. Roughly half of that is cells, and the other half is a pale yellow liquid called plasma. The vast majority of these cells are erythrocytes, more commonly known as red blood cells (RBCs). Our red blood cells are the most abundant cell type in the human body accounting for approximately 70% of all your cells. They measure roughly 7 microns in diameter and around 1-2 microns in thickness.

Cytoplasmic streaming in onion cells

All cells are confined by a cell membrane, and in the case of plant cells this membrane is accompanied by a cell wall. Inside this envelope, each cell contains a lot of different organelles, molecules like proteins, carbohydrates and nutrients along with a cytoskeleton for structural support.

The organelles and macromolecules need to move around to get where they are needed. One way of achieving this is through passive diffusion. However, this process is very slow in the crowded cellular cytoplasm where up to 30% of the volume is taken up by macromolecules. To speed things up the cell utilizes a phenomenon called cytoplasmic streaming, also known as protoplasmic streaming and cyclosis. This kind of molecular movement, in contrast to diffusion, is not a passive but an active process which uses energy in the form of ATP (adenosine triphosphate). The energy is spent on moving specialized transport molecules called myosin, kinesin and dynein, along the cellular cytoskeleton while carrying the macromolecules and organelles.

Large cattail

Typha latifolia, called ‘large cattail’ in English, is a water plant that is mainly found in eutrophic and acid water, along the shores of ponds, ditches and in swamps. This perennial has an upward and wide-spread growth habit. It is easy proliferating through rhizomes. If planted in a garden pond, locking it in a good pond basket is the message. The leaves are broad, linear and blue-green colored. Large cattail blooms from June to September with double cigar-shaped ears. The male ears are at the top, the female right below. After wind fertilization, the characteristic brown colored ‘cigars' form the female flowers. The seeds of cattail develop from the flowers on the cigars. The seed fluff is normally transported by the wind. The plant is hardy, endures sea breeze, air pollution and has a beautiful winter silhouette.

 

Pollen bring light into the darkness

A way of classifying pollen species is by monitoring auto fluorescence images of pollen grains. Several components of the exine (i.e. the outer layer of the pollen wall) show conspicuous auto fluorescence in the pollen grain.

The Dujardin coloring technique

The images shown are taken from a beautifully colored prepared slide from the archives of the Royal Antwerp Society for Micrography. The slide is already several decades old. It shows a cross-section of a twig of the plane tree. In spite of the age of the slide, the colors are still clear and fresh thanks to the use of the simple simultaneous Dujardin coloring method. During the coloring the colors were brought into balance with great skill, showing the various plant tissues. On the fluorescence image the plant various tissues are shown in a different manner.

This is not possible with our epidermis

The scales of a fish are slanted in the skin of the fish and consist of collagen, calcium phosphate and calcium carbonate. They overlap and form a firm layer that protects the fish against injuries, parasites and enemies. In many cases they also serve as reflectors or give colors.

What’s in a buttercup bud?

The images shown are taken from a beautifully colored prepared slide from the archives of the Royal Antwerp Society for Micrography. The slide is already quite old, from 1988. It shows a cross-section of a bud of the buttercup (Ranunculus) In spite of the age of the slide, the colors are still clear and fresh. Coloring has been carried out with the dyes sun-yellow, crocein scarlet and astra blue. The very thin coupe has been embedded in the resin Euperal. The use of yellow and blue colored dyes, resulted in green colored plant tissues, which is quite special.

A fluorescent flea

Almost daily we have to deal with arthropods such as insects, spiders and their kind around us. Yet we realize less often that these animals can provide a beautiful light show.

Fireflies and other bioluminescent animals produce their luminous shine through a chemical reaction. Other arthropods produce light via fluorescence. At certain wavelengths of light including ultraviolet light, molecules in their exoskeleton absorb this light and radiate it again in a different color with a (longer) wavelength, (there are 'excited electrons' involved, but let's skip the details here)

Protected against harsh conditions

Helm grass is what we encounter in the dunes among others in the Netherlands. The Ammophillia arenaria can withstand the salty water and salty sea air. Ammophillia arenaria can be planted on all types of soil, only on clay soil it is best to make the soil poor with masonry sand. The soil must be calcareous.

A Casuarina cunninghamiana from Australia

The Casuarina cunninghamiana or the River She-Oak is a large, fast-growing, pine-like tree native to the east of New South Wales and Queensland, Australia. The tree, an evergreen, has thin needle-like, flexible green twigs practically without leaves. An image of a cross section thereof is shown here. The epidermis shows a structure which is a little similar to that of pine needles.

The Casuarina cunninghamiana is one of the tallest trees of its kind and can reach a height of 30-35 m. Its straight stem branches are quite low and its bark is greyish brown, rough and cracked so that it often comes loose in strips. The plants can easily be grown from seeds. In some countries it is considered an invasive species because it can surpass indigenous plant communities.