Transport System Basics
Every animal needs to move stuff around their body, and there are some brilliant patterns in how they do it. Transport systems always need a liquid medium (like blood), a pump (usually a heart), and valves to keep everything flowing in the right direction.
The clever bit is that some animals, like us, also have respiratory pigments such as haemoglobin that massively boost how much oxygen we can carry. Insects don't bother with this because they get oxygen directly through their breathing tubes.
Open circulatory systems work like a blood bath - literally! Insects pump blood into a body cavity called the haemocoel, where it sloshes around the organs directly. It's low pressure but works perfectly for their needs since oxygen reaches tissues through separate tubes anyway.
Closed circulatory systems keep blood locked in vessels, creating two main types: single circulation (like fish, where blood goes heart → gills → body → heart) and double circulation (like mammals, where blood passes through the heart twice per circuit).
Quick Tip: Remember that mammals need double circulation because blood pressure drops in the lungs - sending it back through the heart gives it the boost needed to reach your toes!
