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Dieren en planten

Water en land

Mens en Milieu


Catches and finds plants animals
blue crab
sea lavender
cuckoo flower
lichens fungi, toadstools cyanobacteria
on rocky coasts
fungi in the sea
protists bacteria archaea
protists bacteria archaea

Living nature contains an enormous variety in different organisms. In order to get an overview of this variety, species have been classified in all kinds of manners. Scientific classifications can be based upon internal build and genetic relationships. More everyday classifications consider appearance in particular. Due to increasing scientific insight, the manners of classification continue to diverge from one another.

  • Scientific classification

    Scientific classifications try as much as possible to give an impression of the relationship between organisms. That is why as insight grows, these classifications continually change. A scientific classification is organized in a hierarchy. A number of species are grouped together into a genus, a number of genusses into families and so on until all organisms fall under a small number of kingdoms.
    Organisms can be classified in various ways. As more and more research takes place, our knowledge changes and thusly the classifications. For practical reasons, the classification used here involves seven groups, which are easy to distinguished based upon their form. These seven groups correspond well with the seven kingdoms often applied in science.

    Prokaryotes : cells lacking a nucleus or surrounded by a membrane
    Domain 1 Archaeon (single-celled micro organisms)
    Domain 2 Bacteria - cells with a nucleus not surrounded by a membrane
    bacteria (Eubacteria)
    blue-green algae (cyanobacteria)
    Eukaryotes - cells with a nucleus surrounded by a membrane
    Domain 3 protist

    Prions and viruses are excluded from this classification. According to some people, viruses do not belong to living organisms because they cannot reproduce independently. However particularly in the sea, their presence is of tremendous ecological importance. Prions are not considered 'living'. They are independently appearing proteins that are not a part of a living organism. Prions can cause fatal illnesses, such as mad cow disease and schrapie in sheep.

  • Disputable groups

    Algae - this group consists of microscopically small species as well as larger species, usually referred to as seaweeds. In this group, there are Dutch species that can grow to 1 meter long. Some foreign species can grow to dozens of meters long. Because algae perform photosynthesis, it has similarities with plants. The one-celled algae falls under domein 1 while all other algae fall under domain 3. Blue-green algae, or cyanobacteria, belong to domain 2. Eelgrass grows in the sea and looks like a seaweed, however it is a plant.
    Toadstools - this group consists of the fruit of organisms that are barely visible. Most toadstools are the fruit of species that belong to the fifth kingdom (fungi) although the fourth kingdom (protists) contains toadstool-like fruit bodies such as the slime molds.
    Moss - this group falls under the plant kingdom (kingdom 6).
    Lichens - fall under the fifth kingdom (fungi).
    Plants - this group contains exclusively representatives from the sixth kingdom. Therefore, there is no confusion whether or not groups such as algae, toadstools and lichens should be categorized as plants. The term 'higher plants' is often used to refer to plants with flowers in order to distinguish them from moss and ferns within the plant kingdom.
    Shells - this group consists of the hard parts of the molluscs. In addition to shells, other remains of molluscs wash ashore, such as the internal shells of cuttlefish.
    Fish - this group is part of the animal kingdom. Other animals also live in the sea that look like fish, but belong to the mammals, such as whales and dolphins.