There are many organisms that live on
Earth. Some have feet, some swim, and some fly. They come in all shapes and
sizes. They all have two things in common: (1) they have to reproduce and (2)
they have to eat. In order for humans to determine how many organisms there
are, scientists developed a way to name and group them. The more we learn
about organisms the more we refine our groups. In ancient Greek times,
Aristotle grouped things into Animal and Plant. Now we group them into 6
kingdoms including: Animals, Plants, Fungi, Protist, Eubacteria (true
bacteria), and Archaeobacteria (primitive type of primitive bacteria.)
Students have previously learned about
large animals, and now we turn their attention to the smaller animals, or
those called invertebrates. The animal kingdom is divided into two major
groups according to the presence or absence of a spinal column (backbone).
Animals with a backbone are called vertebrates and those without are called
invertebrates. The development of the backbone was a major step in large
animal evolution because it allowed these organisms to develop a successful
life on land.
- Ask students which animals they think
belong to either vertebrates or invertebrates. If they say "insects"
or "crabs," put them under "invertebrates." As they give
you examples, group them into the two groups on the board. Get the students to
see that vertebrates tend to be larger organisms. Show students examples from
the Display Kit of Invertebrates.