Which animals have more than one heart?
Humans have one heart. Most animals have one heart, but there are animals with no heart, such as the jellyfish, and there are animals with more than one heart.
The heart transports, or circulates, oxygen in the blood around the body. This is called the circulatory system. The human heart has red blood cells called haemoglobin. The human heart has 4 chambers (two atria and two ventricles). The cockroach, for example, has one heart with 13 chambers. The earthworm has 5 pseudo-hearts (false hearts) that are really aortic arches that act similar to a heart.
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The British band, The Beatles, sang about an Octopus’s Garden in 1969. Is an octopus’s garden real?
The song lyrics mention that the octopus’s garden is under the sea, in the shade, in a lttle hideaway near a cave, and near coral.
It is true that an octopus lives under the sea near coral. It likes to live in marine (saltwater) oceans in shallow lagoons and coral reefs. It is benthic, because it lives on the bottom of the ocean, on the seabed.
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The Giant Pacific Octopus (Enteroctopus dofleini) is a large, marine invertebrate (soft-bodied) mollusc in the Octopoda order. Octopoda means eight limbs. It is a cephalopod, related to the squid, cuttlefish, and nautilus.
The Octopus has a greyish, soft hollow body called a mantle. Its body can change shape and squeeze into small gaps. The mantle has gills (to breath), a brain, and a parrot-beaked mouth. Surrounding the mouth is eight limbs with suckers. It has two large eyes with excellent sight.
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The Giant Squid (Architeuthis dux) is a marine (saltwater) soft-bodied invertebrate cephalopod. It is related to the Octopus and the Nautilus.
The Giant Squid has a grey mantle (body), eight arms, and two longer tentacles. The arms and tentacles are arranged in a circle surrounding the squid’s mouth. Its mouth looks like a parrot’s beak. It has two very large eyes so that it can detect light in the very dark deep ocean.
The inside of its arms and tentacles have hundreds of suction caps, which are 2-5 centimetres (1-2 inches) in diameter. Each tentacle is divided into three segments: (1) carpus (wrist), (2) manus (hand), and (3) dactylus (fingers). It has two large gills to enable it to breathe in oxygen from the water.
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The Chambered Nautilus (Nautilus pompilius) also called the Pearly Nautilus. It is a marine mollusc (mollusk) and a cephalopod (related to the squid and the octopus).
The Chambered Nautilus is similar to a squid, but with an external shell. It has about 90 tentacles, called cirri. The tentacles do not have suckers (like the octopus). The eye of the Chambered Nautilus has no lens.
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