Name three things all Insects have in common.
Well, there are many, many things all insects have on
common, and many of you got most of them. Here’s a little summary of all the
things we can think of….
Insects are Arthropods. All Arthropods have things in common, and so Insects share these
Legs with joints
An exoskeleton made, in part, of chitin (kite en)
Bi-lateral Symmetry (if you make an imaginary line down the middle, they have the same number of appendages on one side as the other)
Insects have other similar characteristics, too. This is how entomologists decide whether or not an animal is an insect or not
6 Legs – 3 on each side
2 Antennas – 1 on each side
3 Main body parts
(They got the name “insects” because their bodies are ‘in sections)
4 Wings (usually)
Compound eyes (usually)
They have other things in common, too. Insects have an 'open circulatory system.' This is a common thing to teach in basic entomology classes. It is also common to point out the structural similarities to the open circulatory system and the closed circulatory system like ours. What most of these sources fail to make a point of is the reason such a simple circulatory system is possible and the real big difference between us and them:
Our blood carries oxygen and other gasses to our cells
Their hemolymph doesn't
Now that may not seem like such a big difference, but it is everything. All of our cells need a fairly constant supply of oxygen and other important gasses in order to do anything - same with bugs. Their bodies are small enough that a system of gas passages, or trachea can get the blood there. Our bodies are too big for this to work and so we need a rather complex plumbing system to transport gasses around to all our cells.
There are other, less obvious thing about insects that they all share, but if you got any of the things above, you were right on target!