Hydra vulgaris

There are several types of Hydra that we can encounter in fresh water, for instance the Hydra Fusca, Hydra Viridis (Green Hydra) and the Hydra Vulgaris. All species have the same nutritional and environmental needs, only the appearance may differ slightly. 

A hydra can have 4 to 12 tentacles with which they catch their prey and can reach a length of 3 centimeters. These tentacles are equipped with nettle cells that paralyze their prey. They can reproduce in various ways, including division. For example, if they are pulled through the middle, both parts will recover and live on. 

Triple Stain Wacker 3A

The Wacker 3A staining method (developed by Robin Wacker) is one of the methods which can be used to distinguish cell differences in plants. The images of the cross section of a Rubus idaeus (raspberry) sprout are showing a nice example:

The method is based on the following solutions: 

• Astra blue (2% in distilled water)
• Acriflavin (1% in distilled water) 
• Acridine red (1% in 50% ethanol).  

*All solutions slightly acidified with 2ml acetic acid per 100ml solution.

It is better not to have this on your skin

Carp Louse. This highly flattened fish parasite is covered with a back shield. At the bottom of the head, the first lower jaws are transformed into suction cups with which they attach to fish. The chest piece consists of only four segments, each of which carries a pair of split-leg shaped swim legs. The abdomen is little developed and not externally articulated.

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.