Six strange animals in the animal kingdom

Six strange animals in the animal kingdom

The heart shape has become a symbol of Valentine's Day, but the heart shape in the real world is not suitable for everyone, especially in the animal kingdom.

The human heart beats about 72 times per minute, but the heart of the hibernating groundhog only beats five times, while the heart of the hummingbird reaches 1260 times per minute in flight.

The human heart weighs about 0.6 kg, while the giraffe's heart weighs about 24 kg, because this organ needs enough power to pump blood into the animal's long neck. Introduce some animals with strange hearts.

Frog with two atria and 1 ventricle —— Drowning toad on the plain

Not all frogs are toads, but all toads belong to frogs.

The hearts of mammals and birds have four atria and ventricles, while frogs have only three, with two atria and 1 ventricle respectively.

Generally speaking, the heart pumps oxygen-deficient blood from the body, sends it to the lungs to get oxygen, and then pumps it to all parts of the body to provide oxygen for organs.

In humans, a four-chamber heart puts oxygenated blood and anaerobic blood into different atria and ventricles. But in a frog's ventricle, a groove called trabecular bone separates oxygenated blood from anaerobic blood.

Frogs can get oxygen not only from their lungs, but also from their skin. The frog's heart takes advantage of this evolutionary quirk. Hypoxic blood enters the right atrium, enters the ventricle, and then flows out from the lungs and skin to get oxygen. Oxygen-containing blood returns to the heart through the left atrium, then enters the ventricle and is exported to the main organs.

The blue whale has a huge heart.

The heart of the blue whale is as big as a car and weighs about 860 Jin. The blue whale is the largest animal today. Like other mammals, it has four chambers.

This organ is responsible for supplying blood to the super-large marine life blue whale. The thickness of the aortic wall can reach the length of iPhone 6 Plus. That's a thick-walled blood vessel.

Cephalopods have three hearts.

Cephalopods are by no means half-hearted. These tentacle-like marine creatures, including octopus, squid and cuttlefish, each have three hearts. It's just that the names and functions of these three hearts are different. The middle is called the body center, and the two sides are called the gill centers.

The two gill centers on both sides of the cephalopod body pump blood into the body for oxygen supply through the blood vessels of the gills, and the heart in the center of the whole body pumps oxygenated blood from the gills to other parts of the body.

Cephalopods are actually nobles because their blood contains copper. Human blood is red because hemoglobin contains iron. Just as rust is red, the iron in our hemoglobin is red after oxidation. But in cephalopods, oxygenated blood turns blue.

Cockroaches have only 1 heart, but 13 heart cavities.

Like other insects, cockroaches have an open circulatory system, which means that their blood will not fill their blood vessels. Blood flows through a single structure with 12~ 13 chambers.

The dorsal sinus (also called pericardial cavity) of cockroaches is located at the top, which helps to transport oxygenated blood to every chamber of the heart. But the heart is not used to transport oxygenated blood.

Cockroaches and other insects breathe through air valves (surface openings) in the body, not through the lungs, so blood does not need to transport oxygen from one place to another.

On the contrary, blood called hemolymph carries nutrients and is white or yellow. The heart can't beat by itself, and the expansion and contraction of muscles in the cavity help the heart transport blood lymph to other parts of the body. Wingless cockroaches usually have smaller hearts than flying cockroaches, and their heart rates are similar to those of humans.

Earthworms have five false hearts.

Earthworms can't summon up courage because they don't have courage. Instead, they have five fake hearts around their esophagus. These fake hearts do not pump blood, but squeeze blood vessels to help blood circulate in earthworms.

Earthworms also have no lungs, but they absorb oxygen through moist skin.

The air in the soil or the air on the wet ground after rain dissolves in earthworm skin mucus, and oxygen is sucked into cells and blood system and pumped to all parts of the body.

The red blood of earthworm contains hemoglobin, which is a kind of protein carrying oxygen. But unlike humans, earthworms have an open circulatory system, so hemoglobin just floats in other liquids.

Heart regeneration of zebrafish

If zebrafish has a broken heart, it can simply regenerate one. A study found that zebrafish can completely regenerate myocardium in just two months after 20% myocardial injury.

The human liver can be regenerated, and the tails of amphibians and some lizards can also be regenerated, but zebrafish's regenerative ability makes it the main object of studying heart growth.

However, fish have a unique heart. They have an atrium and a ventricle, but they also have two structures that are invisible in humans. These two special structures are venous sinus and arterial bulb. The venous sinus is a sac located in front of the atrium, and the arterial bulb is a catheter located behind the ventricle.

Like other animals, fish's heart pushes blood to flow all over the body. Hypoxic blood enters the venous sinus, then flows into the atrium, and finally pumps blood from the atrium into the ventricle. The ventricular wall is thicker and the muscles are more developed, pumping blood into the bulbar artery. When blood flows through the capillaries around fish gills, the arterial ball regulates blood pressure. In gills, oxygen enters the blood through the cell membrane.

But why does this fish need arterial balls to regulate blood pressure?

Because fish gills are very fragile and thin-walled, any fisherman knows this. If blood pressure is too high, fish gills will be damaged. Compared with the muscular nature of the ventricle, the arterial ball itself is obviously a chamber with very elastic components.