ns am a research scientist at The college of Nottingham. My main area of study is cardiovascular biology and also I aid teach college students to come to be veterinary surgeons and also scientists. As soon as I am no working, I bring out a lot of community and charity work and love security time through my family, including my two grandchildren. I have three children. The youngest has actually just perfect school and the larger two have completed their levels at university.

ns am a Manchester-based scientific research communicator and also artist right now researching exactly how art and also games have the right to be offered as devices for scientific research outreach, as component of a M.Sc. In ~ the university of Hull. Ns have functioned in collaboration with researchers everywhere the world, creating interdisciplinary jobs that are used to interact science to the public and to inspire people to get connected in STEM.

i am a teacher and have teach young civilization for end 20 years. I am likewise a skilled proofreader and copy-editor and much more recently I have written my first children’s novel. I have two children, Joshua and also Erin, who love learning around animals and science. In mine spare time, I gain playing tennis to keep my love fit and also healthy and also my enthusiasm for the theater and acting keeps my heart racing, specifically on opening night.


ns am an combine Professor that Anatomy and also Developmental genes at The university of Nottingham and a 2019 British science Association Media Fellow. I lead a group of study scientists investigating why people and also animals suffer from heart and blood vessel disorders, searching for techniques to detect, prevent, and also cure. Once I am not working, ns love come travel roughly the world, visit museums, and also write science fiction. My boyfriend Andrew and also I go running to store our understanding healthy. *catrin.rutland

Young Reviewers

Age: 11

cheerful boy that loves come play basketball and also be v his family.

Age: 15

Hi, my surname is Bruna and also I live in São Paulo.


We all take our hearts for granted: the fascinating organ inside everyone the beats repetitively to keep blood pumping with our bodies. Blood circulation ensures the oxygen, nutrient from food, hormones, and waste assets get to the exactly cells. The love is important for keeping humans and also most pets alive. Hearts room even an ext interesting when we study what lock do, exactly how they look, how they work, and also the similarities and differences in the hearts of types across the planet. Is a giraffe heart comparable to a person heart? Which pet survives in spite of having no heart? can a heart really beat over 1,500 time a minute? indigenous dinosaurs come insects, human beings to dogs, this document looks in ~ what is really happening on the inside, trying out the human being of heart anatomy.

You are watching: Does a giraffe have two hearts

How many Hearts do We Have?

You surely recognize that humans and giraffes have just one heart, as most animals do—but not all. Octopuses and squids (animals called cephalopods) have three hearts. 2 hearts pump blood come the gills to take up oxygen, and the various other pumps blood approximately the human body (Figure 1). Worms are also unusual, with 5 structures called aortic arches acting as simple hearts. The hagfish, sometimes referred to as the slime eel, has actually one true love plus three accessory pumps help the blood come move. Just when you thought you had actually heard that all, some animals are heartless. Jellyfish, starfish, and even corals manage really well without hearts. Starfish do not even have blood, so this describes why no heart is required. Instead, lock use small hair-like structures dubbed cilia to push seawater with their bodies and they extract oxygen native the water.

Figure 1 - The simple structures of pet hearts.Bird and also mammal hearts have 4 chambers (two atria and two ventricles). A frog, i beg your pardon is an amphibian, has a heart with 3 chambers (one ventricle and also two atria), and fish hearts have actually two chambers (one atrium and one ventricle). An octopus heart system contains three hearts—one main heart (H1) pumping blood to the body and also two other hearts (H2 and also H3) pump blood to the gills. A, atrium; V, ventricle.

For Dr. Who fans, the fictitious Time Lords have actually two hearts, but real humans very rarely do. In extremely unusual cases, civilization with the condition cardiomyopathy have actually a 2nd heart attached top top their own heart through doctors. The healthy and damaged hearts job-related together to share the load. Also, pair that room born connected to each various other (conjoined twins) deserve to have 2 hearts naturally.

Mammal and Bird Hearts

It is not just the variety of hearts that can readjust between species. The straightforward structure of this critical organ can be extremely various from one types to the next. Hearts largely consist of muscle that contracts and relaxes, leading to blood to move through blood ship to and from the lungs and also around the human body (Figure 2)1. Together mammals, we have four main parts to the heart, a left and a best atrium and also a left and also a ideal ventricle. This is dubbed a four-chambered heart. Various other mammals and also birds all have four-chambered hearts. Other animal groups, such as reptiles, amphibians, fish, and also insects, have actually hearts the look a little different (Figure 1).

Figure 2 - mind have adjusted differently to best suit every animal.(A) The giraffe has actually a very large left ventricle so the the love muscle can pump blood come the body and also all the method up the long neck come the head. The giraffe’s best ventricle is smaller, together it just pumps blood to the lungs. Microscope photos of the heart muscle that a chick (B) and a dog (C) are likewise shown. The chick is young and therefore only has one ventricle and also one atrium. Later, the chick heart will come to be four-chambered, v two atria and two ventricles.

Reptile and Dinosaur Hearts

Reptile hearts have actually three chambers, two atria and also one ventricle (Figure 1). The exemption is crocodilians, which have actually four-chambered hearts, as with mammals and birds. However, over there is a hole in the crocodile chamber wall, so whether there are three or four heart chambers is up because that debate. Civilization often wonder whether dinosaurs developed from birds or reptiles. Recognize a dinosaur love is an extremely rare because, uneven bone, the heart is a soft tissue, so the is not frequently preserved. One perhaps fossilized heart appeared to present that dinosaurs had 4 heart chambers, an ext like birds 보다 reptiles. Sadly, as this specimen was investigated additional using an ext advanced clinical technology, the was found not to it is in dinosaur tissue, so us still carry out not understand enough about dinosaur hearts come predict which animals dinosaurs evolved from <2>.

Amphibian Hearts

Amphibians room an exciting group, together their hearts vary greatly. Life on land and also in water, many get oxygen making use of their lungs, but likewise take it increase via their skin. Most amphibians, consisting of frogs and toads, have three-chambered hearts, with two atria and one ventricle (Figure 1). However, lungless salamanders perform not have a structure referred to as a septum to divide the atrium into two different parts, so this pet has just one atrium and also one ventricle. Part lesser recognized amphibians it seems to be ~ to have a septum in in between their ventricles, therefore perhaps old amphibians had actually four-chambered hearts, prefer mammals and also birds.

Fish and also Insect Hearts

Fish hearts have just 2 chambers, one atrium and a ventricle (Figure 1). Insects regularly have simply a tube the pumps hemolymph (the surname for the insect indistinguishable of blood) freely roughly the whole body, through a vessel to assist it move. Cockroaches, however, have 13 love chambers!

How big is her Heart?

It goes without saying that heart dimension varies in various animals. ~ all, a whale could not make it through with a mouse-sized heart. One adult person heart weighs around 0.6 lbs. If you do a fist, that is around the size of her heart. The giraffe heart is a hefty 26 lbs, but the blue whale really tips the scale at 400 lbs. The world’s the smallest heart belongs to the fairyfly. This tiny animal is simply 0.2 mm long, and also a microscope is needed to see its heart.

Hearts space normally about 0.6% of an animal’s human body mass. Dogs and wolves have relatively large hearts in comparison v their weight, in ~ 0.8%. Meanwhile, the cat heart is simply 0.35% of a cat’s human body weight. Hopefully, relative heart size and also the lot of love pets feel room not related. If castle were, the world’s smallest mammal, the Etruscan shrew, would have actually a the majority of love come give! The mouse-like shrew weighs a tiny 2 g and is around 4 centimeter long, but its heart makes up 1.2% that its body load <3>. Scientists additionally found the the shrew heart deserve to shrink in cold weather. This shrinkage helps shrews make it through harsh climates, by reducing the quantity of food that needs. This little mammal eats double its body load in food every day, therefore hibernation is not an option. They rarely even sleep.

Swift and Sluggish love Rates

The method animals’ hearts work varies between species, too. The heart rate, measure in beats per minute (bpm), varies in different species. Generally, larger animals have slower heart rates. A big slug has a heart price of around 55 bpm, while smaller sized slug types are in the 90s. Plenty of whales have actually heart prices of 10–30 bpm, giraffes space 40–90, and cats are approximately 150. In even smaller animals, the number increases: an adult chicken has actually a heart rate of 259 bpm, a chick is 400 (Video 1), and also the hamster heart beats away at 450 bpm. The tiny Etruscan shrew clocks 835 bpm, an ext than 12 times higher than a person. The highest possible recorded shrew price was 1,511 bpm, a people record for a warm-blooded pet <3>.

People have actually heart rates of about 60–100 bpm, however children regularly have slightly higher rates. In ~ 1 month old, 70–190 is fairly normal, 80–120 for 3–4-years-olds, and also 60–100 by the time a son is 10 year old. A cultivation baby within its mother starts at 80 bpm in week 5, 155–195 in ~ 9 weeks old, and also around 130 just before it is born. Interestingly, the human being heart starts together a pipe in the 19–20-days-old embryo, rather choose a fish, but gradually rotates, develops, and also separates into 4 chambers over the next 6 weeks.

Exercise, Temperature and also Hibernation All adjust Heart Rate

Heart rate changes in most working out animals. Running giraffes can reach 170 bpm and also humans can hit 220, yet ideally it must be a tiny less. A crocodile heart rate at 10° C is 1–8 bpm, at 28° C it access time 24–40, and once that reaches over 40° C, the heart can come to be damaged. Young swifts (birds) reduced their heart rates when in the nest, to avoid starvation. Hibernating animals can also lower your heart rates. Grizzly bears usually clock 84 bpm, which lowers to 19 bpm during hibernation; a person heart would certainly usually protect against working if that went the low. Emotions, such as fear, love, and excitement, and also hormone levels, sickness, oxygen levels, and other components both inside and also outside the the human body can adjust the heart rate.

Mending a damaged Heart

In our previous Frontiers for Young Minds document “Mending a broken Heart,” us looked at solving failing understanding <4, 5>. The zebrafish has a very important ability: it can regenerate (regrow), therefore if it gets injured or its heart has actually a problem, it can frequently repair itself. Human being bodies are fantastic, and also they continuously shot to change heart cells and also repair heart tissue, yet the zebrafish is a real experienced at repair a damaged heart.


In this article, we looked at several of the similarities and differences in between the mind of miscellaneous species. Mammals and birds have very comparable hearts due to evolution, if reptiles, fish, insects, and also other pets evolved understanding that space slightly in different ways from those the mammals. The setting both inside and also outside the each pet helps control the heart’s structure and also function, yet lifestyle choices, such together exercise and food, can have huge impacts on her heart’s health. Her friends’ hearts are more similar come yours than to a giraffe’s because that example, and even an ext similar 보다 to a frog or spider heart, however every person’s love is unique. Your heart is continually adapting come the instances you room in, reacting to food, exercise, emotions, and also illness. Unequal a squid, friend only have actually one heart, and it will certainly beat around 2.21 billion time in her life, so the is worth maintaining it healthy.


Cephalopods: pets without backbones, consisting of squids, octopi, and also nautiluses. Cephalopods have actually symmetrical bodies, influential heads, and tentacles.

Atrium: The top chamber or chambers that the heart. The many is atria: because that example, you have the right to have one atrium or 2 atria.

Ventricle: The lower chamber or chambers that the heart.

Amphibian: animals with backbones that need water or wet atmospheres to survive. Amphibians encompass toads, frogs, salamanders, and caecilians (amphibians without foot or limbs).

Hemolymph: Fluid, similar to blood, that some straightforward animals have to move nutrients and also oxygen roughly their bodies.

Heart Rate: The variety of times every minute the a heart beats.

Video 1: beforehand on, as soon as a chick is farming in one egg, its heart have the right to be watched on the exterior of its body. End time, the heart will relocate inside the body. This video shows a chick’s love beating as soon as it is simply a couple of days old. The love is quiet a tube containing 2 chambers, a ventricle and also an atrium, yet as it grows it will ultimately have 4 chambers. You have the right to see the blood pumping v the heart chambers.

Conflict of Interest

The authors declare the the research study was performed in the absence of any kind of commercial or financial relationship that could be interpreted as a potential problem of interest.


The writer would favor to thank our young reviewers, Erin and also Joshua Rutland. Component of this job-related was made possible due to resources from the Anatomical culture with a publicly Engagement and Outreach grant to Catrin titled Anatomy for ALL—Making Anatomy Accessible. Us would also like to say thanks to the British scientific research Association and University that Nottingham because that awarding Catrin through a BSA Media Fellowship 2019.


1. view the paper “Blood vessels Under the Microscope” because that information about blood <1>.

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<1> Machado, M., Mitchell, C., Franklin, J., Thorpe, A., and also Rutland, C. S. 2020. Blood vessels under the microscope. Front. Young mental 8:151. Doi: 10.3389/frym.2019.00151

<2> Cleland, T., Stoskopf, M., and Schweitzer, M. 2011. Histological, chemical, and also morphological reexamination of the “heart” that a tiny Late Cretaceous Thescelosaurus. Naturwissenschaften. 98, 203–211. Doi: 10.1007/s00114-010-0760-1

<3> Jurgens, K. D., Fons, R., Peters, T., and also Sender, S. 1996. Heart and also respiratory rates and also their meaning for convective oxygen transport rates in the the smallest mammal, the Etruscan shrew Suncus etruscus. J. Exp. Biol. 199:2579–84.

<4> Clark, N., Alibhai, A., and Rutland, C. S. 2018. Mending a damaged heart—the genes of love disease. Front. Young mental 6:19. Doi: 10.3389/frym.2018.00019

<5> Simpson, S., Rutland, P., and also Rutland, C. S. 2017. Genomic insights into cardiomyopathies: a to compare cross-species review. Vet. Sci. 4:19. Doi: 10.3390/vetsci4010019