Once again we’ll be talking about honey bee biology, as it says in the title! Let’s get right into it:

The Respiratory System

I want to begin with a very quick generic biology lesson. Why do animals breathe? If you’re a biology major you probably know so many specifics I can’t even begin to remember, but for people like me: oxygen and food combine through a complicated process I’m just going to call our metabolism to make water, CO2 and ATP. ATP is the main energy source for our cells, and to make it we have to breathe!

You might have read one of my previous posts talking about how bees share nectar through vomiting, suck nectar up with their tongues and do a lot more crazy things with their mouths, so you might wonder how they breathe through all of that. The answer: they don’t breathe through their mouths at all! Bees, like most insects, breathe through their abdomens (fig 1). There are tiny holes in their exoskeletons that, when they squeeze in the right way, create a negative pressure to intake air. In this video, the bee in the middle is wiggling her butt––that’s the bee breathing!

Those holes are called spiracles and, after air passes through a dust filter, they follow into the trachea, which are tiny and vein like, except no blood flows through them––only air. The trachea split up into tracheoles, which are smaller tubes, and these are all throughout the bee, funnelling the air into cells.

Next is the Circulatory System!

You might have noticed there is no connection between the circulatory system and the respiratory one, unlike in humans where the two are so attached they may be called the cardio-respiratory system. Another difference: in humans, we have a closed circulatory system, meaning all of our blood remains in our veins. Bees have an open circulatory system, which means… Well, it’s a tad complicated.

Honey bees do have veins, or, really, just the one vein, pictured to left (fig 3). Ignore the bottom most red line and the middle, individual line. We care about the tube running from the head to the back of the body. This is the bee’s circulatory system. It runs on hemolymph, carrying, instead of oxygen, fluid plasma (salts, amino acids, and proteins) as well as blood cells. Their functions are nutrient and waste transport, a sort of immune response (no where near as complex as our own), and hormone signalling.

The part of the system in the thorax (the middle segment of the bee) is called the dorsal aorta and the part in the abdomen (the butt) is called the dorsal heart. The dorsal heart pulses as the bee moves to breathe and this pushes blood towards the head, taking nutrients from the digestive system. In the head the blood changes direction and sloshes back to the dorsal heart to begin the cycle anew.

Honestly one of the most mind blowing things about bee biology to me is that the blood just flows freely back to its heart, bathing all the necessary internal organs in blood on the way there and back. It’s so spontaneous and uncontrolled I’m surprised it works. Bees are much smaller than humans, though, and many insects employ this tactic rather than giving up valuable internal room to a complex network of veins.

Also, I feel obligated to put at least one fuzzy bee photo in every post so here’s your dose of fuzzy bee for today. Seriously though, look at the cute girl all covered in pollen (fig 3)!

Information for this post came from: Ellis, Jamie. “The Internal Anatomy of the Honey Bee.” The American Bee Journal. Sept 1, 2015.