Since cucumbers and sea cucumbers both get nutrition from the soil, why are cucumbers plants and sea cucumbers animals?
Welcome to taxonomy — the science of classifying living things. Many
taxonomists (not all!) sort life forms into five major categories or
kingdoms. According to them, kingdom Protista contains single-cell
organisms with a nucleus.
Kingdom Monera contains single-cell organisms without a nucleus.
Animals are life forms that belong to kingdom Animalia, from the Latin
word for “breath” or “soul.” They have more than one cell and are
heterotrophs, meaning that they are nourished by other life forms.
Kingdom Fungi contains multi-celled, heterotrophic life forms, such as
mushrooms, which absorb nutrition from decaying organisms. Genetic
studies show that mushrooms are more like animals than plants. Life
forms in kingdom Plantae are multi-celled autotrophs, meaning that they
make their food. Plants are producers; animals and fungi are consumers.
In general, cucumbers are plants because they create nourishment from
elements in the soil. Sea cucumbers are animals because they get
nourishment from plants and animals in the sediment they swallow. Dirt is just their vehicle for dinner.
People have eaten cucumbers and sea cucumbers for centuries.
Cucumbers were probably first cultivated in northern India. The part we
eat is actually a fruit, like grapes or melons. Some sea cucumbers go to
great lengths not to be eaten. They push their intestines out and
“slime” attackers, and then regenerate new intestines. (Pretty gutsy!
And disgusting!). Video
Here's a challenge for taxonomists: Are meat-eating plants such as
Venus flytraps really animals? Carnivorous plants thrive when they
digest an insect or a lizard now and then. But they can survive without
meat, and they have other plant-like characteristics, so they are
classified as plants.
Taxonomy can be taxing!
- What is taxonomy?
- Explain the sentence "Taxonomy can be taxing"
- Why shouldn't you eat some huge sea cucumbers?
- Do you agree or disagree with the way taxonomists have classified the Venus flytrap? Why or why not? Write down your answer.
- You know about the five kingdoms used to classify organisms: monerans, protists, fungi, plants, and animals. Invent an organism that has characteristics from two of the different kingdoms, such as a Venus flytrap. Write a short paragraph describing your organism. Name the two kingdoms in which it could be classified. Describe how your organism gets or makes food, moves (or doesn't move), how big or small it is, and whether it lives in a colony or alone.
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