Most reptiles have two atria and one ventricle. The only exceptions are the 23 living species of crocodilians (alligators, caimans, crocodiles and gharials) who, like birds and mammals, have four-chambered hearts with two atria and two ventricles (Jones, 1996; Jensen et al., 2014).
Crocodilians have a four-chambered heart – just like people! And just like the circulatory system in people, the heart takes in deoxygenated blood from the body, sends it to the lungs to become oxygenated, the blood comes back to the heart, where it will then be pumped to the rest of the body.
The crocodiles are only the reptile that has a four-chambered heart (two atria and two ventricles) because of the most complicated blood circulation of all vertebrates. They spent most of their time underwater, so this adaptation (four-chambered) helps to a reduced rate of circulation and save oxygen.
Birds and mammals, however, have a fully septated ventricle--a bona fide four-chambered heart. This configuration ensures the separation of low-pressure circulation to the lungs, and high-pressure pumping into the rest of the body.
Fishes have two chambered heart. Frog [ amphibian ] have 3 chambered heart whereas crocodile [reptile] and peacock [aves] have four chambered heart.
Such an enormous pressure would require a very large, strong and slow-beating heart. But, they postulate, instead of a single large heart, the Barosaurus probably had some eight hearts.
To many, leeches are horrifying creatures. To a few, they're impressive and miraculous. They have 32 brains, 2 hearts, 300 teeth grouped in 3 jaws, five pairs of eyes...
There is a systemic heart, the main heart, and two lesser hearts that pump blood to the gills where waste is discarded and oxygen is received. They are also the world's tallest mammals.
Earthworms are one of the most common animals with multiple hearts. These decomposers can be found pretty much everywhere, as long as there's dirt for them to live in.
It is an octopus. Yes, the multi-tentacled creature that has always intrigued us has three hearts and nine hearts. Read on to know why. The two hearts of this creature are made for the gills and are used to pump blood.
Scientists have found the first-ever fossilized dinosaur heart, and it appears to have four chambers, perhaps the strongest indication yet that dinosaurs were warmblooded animals, like birds and mammals.
The hearts of all snakes and lizards consist of two atria and a single incompletely divided ventricle.
Fishes have only two chambers of the heart- the atrium and ventricle. The oxygenation of blood happens through the gills.
Most reptiles have two atria and one ventricle. The only exceptions are the 23 living species of crocodilians (alligators, caimans, crocodiles and gharials) who, like birds and mammals, have four-chambered hearts with two atria and two ventricles (Jones, 1996; Jensen et al., 2014).
We examined 21 hearts of the Nile crocodile (Crocodylus niloticus) from the UCL Cardiac Archive, held at the UCL Great Ormond Street Institute of Child Health. The largest heart weighed 150 g and the smallest five examples, from fetal specimens, weighed just < 1 g.
They Have Crazily Small Brains
It's approximately 0.01% of their body weight. As a matter of fact, a 3.5 metre croc has a brain the size of a walnut! However, they are very intelligent animals.
Spiders usually have eight eyes but few have good eyesight.
Some spiders have median eyes that can detect polarised light and they use this ability to navigate while hunting.
To date, there's only one species that has been called 'biologically immortal': the jellyfish Turritopsis dohrnii. These small, transparent animals hang out in oceans around the world and can turn back time by reverting to an earlier stage of their life cycle.
Heart. Oxygen is pumped around its enormous body by an equally massive, four-chambered heart. Weighing some 900kg – and the size of a Mini car – the blue whale's heart beats once every 10 seconds, pumping 220 litres of blood through its body, and beats so loudly it can be heard from 3km away through sonar equipment.
Ants, like other insects, have a heart that pumps hemolymph rhythmically.
One of its four hearts, a branchial heart, pumps blood to the entire body while the other three are considered accessory pumps. They thrive on the bottom of the ocean floor, where oxygen is scarce, scavenging for fish or even dead carcasses to feed on.
Horses, like other mammals, have only one heart. However, the frog in each hoof acts like a pump to push blood back up the leg with each step a horse takes.
Pigs like other mammals have a four-chambered heart. The right side of the heart pumps blood to the lungs (pulmonary circulation), and the left side pumps blood out to the rest of the body (systemic circulation).
Snails have more teeth than any animal.
A snail's mouth is no larger than the head of a pin, but can have over 25,000 teeth (but these aren't like regular teeth, they are on its tongue).
Can you guess what animals might have blue blood? Lobsters, crabs, pillbugs, shrimp, octopus, crayfish, scallops, barnacles, snails, small worms (except earthworms), clams, squid, slugs, mussels, horseshoe crabs, most spiders.