The bloodis pumped by the heart and carries oxygen and necessary nutrients throughoutthe body, and waste products and carbon dioxide that will be eliminated fromthe body.
So, within the mammalian cardiovascular system, the heart is an important anatomical feature – a body organ that has a critical role in mammalian wellbeing.
Other types of animal also have a closed cardiovascular system that includes a heart: birds; fish; reptiles for example, although there are a few evolutionary differences between them
Insects (and other types of animal from the phylum Arthropoda, such as arachnids, and crustaceans) do not have the same circulatory system as mammals.
But insects like bees still have to ensure an oxygen and nutrient supply to their organs – so what system do they have to achieve this? They have an open circulatory system!
Do bees have blood and do they need a heart?
In placeof blood, insects have a fluid called hemolymph. This hemolymph contains immune system cells(hemocytes) in a fluid plasma.
Theplasma contains hemocyanin (the chemical that carries oxygen instead ofhaemoglobin); as well as a number of electrolytes and nutrients. This hemolymph is in direct contact with theorgans in the body cavity (the hemocoel).
In humans, blood is pumped around the body by a heart, but what about hemolymph, how is it moved around the insect body?
There are three ways the hemolymph is moved around insect bodies: whenthe insect is moving, the muscle movements lead to hemolymph movement;specialist muscle movements can occur specifically to move hemolymph; thehemolymph is pumped by a heart.
So, insects have aheart! Bees are insects – so yes, bees do have hearts.
The Bee Heart
The beeheart, however, is quite different from the human heart.
Like other insects,bees have an organ that runs down their back, from the abdomen into theirthorax and into their head. This is thebees’ heart. The part in the abdomen isknown as the dorsal heart, while the part in the thorax is known as the dorsalaorta.
It is effectively a single tubethat contracts – pumping hemolymph into the rest of the body cavity. When the dorsal heart contracts, hemolymph isforced through the dorsal aorta into the head, from where it percolates downthrough the body into the abdomen – bathing the bees’ organs as it goes.
When the dorsal heart relaxes, hemolymph isdrawn back into it, to be pumped up towards the head again.
So, in the sense that the circulatory systemuses a heart to pump fluid around the body, the bee and mammalian system sharecommon characteristics. The bee heartand circulatory system, however, are quite different from the mammalian system.
Read more about bee anatomy.
Could a bee have a heart attack?
So, a beedoes have a heart. Does this mean that abee could have a heart attack? Well,that depends how you define ‘heart attack’!
Mostcommonly, a heart attack (medically known as a myocardial infarction, or MI)occurs when the blood supply to the heart through one or more of the majorarteries that supply the heart itself is blocked – usually by some kind ofblood clot (which is itself usually a build-up of fat and cholesterol).
This blockage can cause the blood supply tothe heart muscle to be stopped, which can lead to tissue death within themuscles, which, if extensive enough, could lead to the heart stoppingcompletely, with fatal consequences.
Technically,therefore, since the hemolymph that supplies oxygen and nutrients to the bee’sheart itself is not delivered by specific tubes that could become blocked, butrather surrounds the tissues directly, it could be said that bees can notsuffer a heart attack as we know them to occur in humans.
Resources
EllisJ., American Bee Journal, 21 September 2015
