Thousands of small lenses work together

Seen from the front, the head of the honeybee has a triangular shape, the head of the drone it is more round. On the head are the eyes, antennae and mouth parts. Important glands are located in the head and the main center of the nervous system: a nerve bud that serves as a brain.

Vorticella - The fastest bell in the world?

Vorticella is a genus of single celled organisms living in both marine- and freshwater habitats. The members of the vorticella genus are commonly referred to as bell animalcules because of their shape. The thing that makes bell animalcules unique are their long stalks which they use to attach themselves to a substrate, which could be things like rocks, twigs and even small animals. The stalks of vorticella resemble our muscle fibers but are able to contract a lot faster than our muscles are. If the cell gets disturbed, it’s able to contract the stalk with an impressive speed of up to 6 meters per second as a defence mechanism to get away from danger or possibly scare predators away.

What exactly is the function of our red blood cells?

Red blood cells (RBCs) also known as erythrocytes are the most abundant cell in the human body. With a staggering number of 25 trillion cells, yes TRILLION, the red blood cells make up around 80% of all your cells. The reason why we have so many of them is because they have a few incredibly important functions critical to our life.

Notice the characteristic donut-shape.

Daphnia’s maneuvers in the dark

Like many other crustaceans, water fleas are very sensitive to light. They have a light-sensitive organ, also called Ocellus, with which they can swim in the direction of the light.

Algae Bloom

 

These beautiful golden spheres are single colonies of the golden algae synura. Like all other organisms, synura is able to reproduce and one colony eventually turns into two. But when conditions are right, reproduction happens a lot more frequently and what used to be a few colonies can quickly turn into an enormous algae bloom. Even though each synura colony is microscopic and only measures around 20-30 microns in diameter. Their large numbers in an algae bloom are able to turn the water in their freshwater habitats a yellowish brown color. A bloom of synura like the one in the image usually happens in spring and fall when the water is cold. But not all algae will bloom in cold water.

Chestnut and the Motic Panthera U

While looking through my new stock of prepared slides, I came across this specimen, a section of a petiole of the Castanea sativa. The Castanea sativa or European chestnut is widespread in Europe and Asia, meanwhile also in other temperate zones. The chestnuts are consumed since ancient times by people. The tree can become very old.

It was not necessary to take multiple photos of the object and stack it. The coupe was cut perfectly flat. The section is stained according to the Wacker 3A procedure (Acridine red -Acriflavin - Astra blue).

Daphnias - Some of the smallest and most common crustaceans

We all know some of the bigger crustaceans like shrimps, lobsters and crabs. But far from all crustaceans are as large as these. Daphnias are some of the smallest crustaceans in the world and can be found in almost all ponds, streams, lakes and other freshwater habitats. Their size ranges from a few hundred microns to around 5 mm for the largest species. Like other crustaceans, daphnias are covered in a hard exoskeleton for protection. Underneath this tough exterior are organs like a heart, a digestive tract, reproductive organs, an eye and a primitive brain. And because daphnias are mostly transparent, it's easy to observe their anatomy on your own.

In the back of the animal is a cavity used for protection of their embryos as they develop. After a few days the babies are fully developed, able to swim and feed, and ready to enter the real world. At some point the mother will lift her foot creating a small opening for the babies to swim out of. In a matter of days, the newborn are ready to reproduce themselves and these animals are therefore able to multiply rapidly when conditions are right.

The embryos on the left are fairly new, but the embryos on the right 

have developed eyes, are able to move and ready to be born

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.

Tardigrades - Microscopic space travellers

Tardigrades are possibly some of the cutest and most popular microorganisms in the world. These microscopic animals can be found in all kinds of habitats all over the planet from high mountains to deep oceans, and even on the poles. However, even though they are very common almost everywhere you will need a microscope to spot them as most species are around 500 microns in size and the biggest ones rarely exceed 1 mm. Tardigrades are more commonly known as water bears, because of their bear-like appearance when they waddle around in the microworld looking for food. Some also call them moss piglets because of their high abundance in moss and lichen samples.

The darkfield illumination makes the individual storage cells clearly visible inside the body cavity, 

as well as the digestive system in the middle of the animal.

Tardigrades have eight legs which all end in a various number of claws depending on the species. Inside the body we find a lot of anatomical resemblance to larger animals as tardigrades both have a fully functioning nervous-, muscle-, and digestive system as well as primitive eyes. But despite a somewhat complex body structure, the animal only consists of a few thousand cells. Some of these are called storage cells which can be seen in the image above. These cells slush around inside of the animal when it walks. In the front tardigrades have a feeding apparatus consisting of stylets used to pierce the food and a pharynx used for chewing. Most tardigrades are herbivores and eat things like algae and other plant material. However, some species are hunters and eat things like bacteria, single celled organisms, rotifers and even other tardigrades.

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.

Nematodes - The most common animal on earth

Around 80% of all animals on the planet are microscopic worms called nematodes, more commonly known as Roundworms. In fact, if you go outside and take a teaspoon of soil you will have caught about 50 of them. However, these tiny organisms are not just present in the soil, but can also be found in aquatic habitats, in moss, on trees and rocks, and almost all other places on the entire planet, from deep oceans, to high mountains.

Synura - The golden algae

When we hear the word algae many of us associate that with the color green. And some algae like desmids, are in fact green. But there are a lot of different kinds of algae, and far from all of them are green. Some are red or red and green like haematococcus, some are blue-green like spirulina, while others are yellowish, brown, or even golden.

Nettles - The healthy stingers

The plant urtica dioica, more commonly known as the stinging nettle, is a plant many of us are unpleasantly familiar with. The quite fitting name ‘nettle’ comes from the anglo-saxon word ‘noedl’ which means ‘needle’ and the latin ‘urtica’ means ‘to burn’. The plant is found worldwide but was originally native to Europe. At its tallest, the nettle grows to around two meters and are equipped with medium sized leaves. Despite many myths both the stem and the leaves are able to sting you as both are covered in the tiny needle-like structures called trichomes or spicules responsible for the burning sensation you get after contact with the plant.

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.

Flatworm digestive tract

The digestive tract of the flatworm, as shown here of a representative of the Dugesia genus, is not very complicated. 

This type of flatworm lives in fresh water. Flatworms absorb their food by mouth in the middle part of their lower body. A small tube shoots from the center of their body at the food and sucks it into the Pharynx. The fresh food is sent to and through the 'intestine', also known as the gastrovascular cavity. There the food is digested. It is spread on all parts of the worm, where the nutrients are needed for growth.

Aeolosoma

Aeolosoma are very small annelid freshwater worms found all over the world. Even though these worms have been known for almost 200 years we do not know much about them. In fact, we know so little that there is still uncertainty on how to spell its name. Some will spell it aeolosoma, while others spell it aelosoma. 

Another mystery yet to be solved is which class of worm it is. Some place it in the same class as earthworms, the oligochaetes. Others place them in the polychaetes with bristle worms, and still others think they belong to their own separate class on the taxonomic tree of life. However it seems like the majority describes them as polychaetes.

Video showing aeolosoma at different magnifications with different microscopy techniques. 

Notice the almost complete clone in the back end of the worm

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.

Rotifers - Some of the smallest animals on earth

Rotifers are some of the smallest animals on the planet. Most measure under 500 microns, but their size can range from only 50 microns to around 2 mm (2000 microns). They are some of the most common microscopic animals, living all over the world in all kind of environments, like freshwater, saltwater, in moss on trees and in the soil underneath your feet. Rotifers are made up of roughly 1000 cells, some of which are specialized to form organ systems. Despite their incredibly small size they have eyes, a small brain and nervous system, and a dedicated digestive system just like us.