Answer:
I think the heart
Explanation:
the heart pumps blood to everything else in the body and keeps everything running.
Answer:
are natural or artificial deposits
The black widow spider is an invertebrate. Its skeleton system hangs outside its body. The only difference between a vertebrate and invertebrate is the presence of backbone or a similar kind of structure with in the body. In case of black widow spider, the internal structural element is missing. Its skeleton system can be classified as exoskeleton.