It really depends on species. For most, if the spider is readily moving, has no growths (eg. fungus) on its body, it is pretty healthy. Saying that, some Spiders don't readily move much eg. trapdoors. It is fairly hard to tell if a spider is unhealthy unless you are observing it from a captive situation.
Spider color
no because spider can kill the cat
That is not possible. Spider-man is not real.
It has eight legs
No, that is fictional information , and is only a fake.
well you tell me... she has 8 legs
there are three that tell of spiders!
"How could you decide if an ecosystem is healthy or not? "
the bowlus spider (spelling probably wrong) saw it on qi
The hump on its back
you tell me hahahahah
Depends on the model. If you didn't know this, ''Spider'' stands for convertible. So there is no such a thing as a Ferrari Spider. Maby you mean F430 Spider, or 360 Spider, 355 Spider etc.. how would i know, but i can tell you that the Spider models cost a little more than a standard Ferrari.