Do Insects Have Hearts? Differences Between Human And Insect Anatomy

Organs in the circulatory system are responsible for pumping blood around a body.

In humans, blood contains oxygen and nutrients, and blood helps to transport these to different parts of the body. However, insects take in oxygen through small openings in their exoskeletons and it is not distributed around their bodies within the blood, but rather by small tubes along the body cavity.

What exactly does an insect's circulatory system do if it does not transport oxygen around the body? The circulatory systems of humans and insects are vastly different, so the functions they play are very different as well!

How many hearts does an insect have?

Insects have an open circulatory system opposite to humans, who have a closed one. They usually only have a single such system in their bodies, which controls the movement of blood.

Unlike human blood, which is thick and red, insects run on hemolymph, which is mostly made of plasma. It resembles a green or yellow watery fluid.

Hemolymph is not red because it does not contain red blood cells which are what mainly transport oxygen around a human body. Instead, oxygen enters the bodies of insects through tiny spiracles or openings in their exoskeletons. They are then distributed through the entire body by tubes called the trachea instead of lungs.

An insect's circulatory fluids are mostly water but contain amino acids, carbohydrates, ions, hormones, lipids, glycerol, and some pigments and cells. Though not as complex as blood, the hemolymph is quite important as it controls the movement of hormones, salts, nutrients, and waste throughout the body and directs it to the right organs in the body cavity.

It helps to protect the body from invasion by viral diseases, bacteria, and internal parasites. An insect's organs only function properly because the dorsal vessel pumps hemolymph to them.

Insect Feelings Vs Human Feelings

It is widely thought that feelings originate in the heart, when we feel emotional pain, warmth, or love, it can be felt in our hearts. The human body is a very complex machine, and the heart and brain are interconnected. This is why feelings that actually originate in the brain can be felt in the heart.

As emotions are usually centered in the brain, strong feelings can trigger blood flow and release adrenaline, which make their way to the heart. This either slows or accelerates a person's heartbeat, which is why someone can 'feel' whatever they are thinking in their hearts at the moment.

Insects do have brains and hearts, however, these are much more primitive than humans. Though it is not clear how they are connected because insects do not have arteries and veins, it has been documented that insects do in fact show a few emotions!

They have been observed to be happy or fly around in delight, or move sluggishly when they are sad or depressed. It is very possible that they do not feel these emotions in their hearts like humans do, but only in their brains.

Structure Of The Insect Heart

An insect's heart is structured very differently from that of humans, which have four chambers.

The hemolymph (circulatory fluid) in an insect's body is transported by a tube running along the length of the body called the dorsal vessel. The dorsal vessel is found in the hemocoel cavity in the abdomen and can be considered to be the heart of an insect.

It is a muscular organ that pumps blood around the body.

The hemolymph enters the dorsal vessel when it is relaxed and leaves when the organ contracts, circulating around the body. The dorsal cavity does have chambers, which keep the hemolymph fluid from flowing backward.

The insect circulatory system is open, unlike the closed one which many animals, including humans have. This means that the blood flow is not contained within blood vessels, but rather just circulates around a body openly.

An insect heart muscle pumps the blood into the hemocoel, which is the primary body cavity in most insects, from where it is distributed to all the organs.

Can insects have heart attacks?

Unlike humans and other animals, insects cannot get heart disease or succumb to heart attacks.

Humans have a closed circulatory system, so it is very easy for blood vessels to get blocked due to the build-up of fats inside, which is what leads to the decrease of red blood cells circulating in bodies, causing severe damage to the heart muscle.

As insects have an open circulatory system, it is not possible for their systems to get blocked as the blood flows freely throughout their bodies, and is not contained by arteries and veins. Unlike vertebrate blood, the blood of invertebrates does not transport oxygen either.

If an insect's trachea gets blocked, it would probably affect the insect's body similar to how a heart attack would affect humans.

Circulatory System Of An Insect

Insects having an open circulatory system, meaning that there are no arteries or veins present to conduct the flow of hemolymph throughout their bodies.

The hemolymph fluid is contained by the dorsal vessel, which contracts to release it into an insect's body, where it circulates freely, carrying carbohydrates, amino acids, and a number of other nutrients to different organs in the body and lubricating all the different tissues.

The journey of the hemolymph begins at the dorsal vessel, from where it is emptied into the body cavity. It first emerges near the brain, which it fully coats helping the brain to function properly.

It then moves on to the other organs in the body. Once the hemolymph visits all the organs in the body, it once again enters the dorsal vessel from the bottom end, which is located near the insect's hind legs.