Answer:
The answer is: They filter microscopic organisms from the waters.
Explanation:
Barnacles are filter feeders, which is why they are usually on dock poles and non-moving structures underwater. They do not need to travel to get food, because it comes to them!
Humans were born with 33 separate vertebrae. However by the time we step to adulthood, most have only 24.
The answer is macrophages. This is a large cell that has the capability of engulfing targeted cells that are infected or damaged. It is a developed monocyte that came from the bloodstream. It has a system of alerting white blood cells and also can be remembered by the immune system once it has been encountered again.
source: https://www.news-medical.net/life-sciences/What-is-a-Macrophage.aspx
