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Octopuses have a closed circulatory system, in which the blood remains inside blood vessels. Octopuses have three hearts; a systemic or main heart that circulates blood around the body and two branchial or gill hearts that pump it through each of the two gills. The systemic heart becomes inactive when the animal is swimming.
[31] [32] In many species of starfish, the large cardiac stomach can be everted to digest food outside the body. Some other species are able to ingest whole food items such as molluscs. [33] Brittle stars, which have varying diets, have a blind gut with no intestine or anus; they expel food waste through their mouth. [34]
A lymph heart is an organ which pumps lymph in lungfishes, amphibians, reptiles, and flightless birds back into the circulatory system. [1] [2] In some amphibian species, lymph hearts are in pairs, and may number as many as 200 in one animal the size of a worm, while newts and salamanders have as many as 16 to 23 pairs of lymph hearts.
Starfish has repeatedly been chosen as a name in military history. Three ships of the Royal Navy have borne the name HMS Starfish: an A-class destroyer launched in 1894; [151] an R-class destroyer launched in 1916; [152] and an S-class submarine launched in 1933 and lost in 1940. [153]
The blood is pumped by three separate hearts: two branchial hearts pump blood to the cuttlefish's pair of gills (one heart for each), and the third pumps blood around the rest of the body. Cuttlefish blood must flow more rapidly than that of most other animals because haemocyanin carries substantially less oxygen than haemoglobin.
They have a seemingly simple brain, not the large complex brains of octopus, cuttlefish and squid, and had long been assumed to lack intelligence. But the cephalopod nervous system is quite different from that of other animals, and recent experiments have shown not only memory, but a changing response to the same event over time. [31] [32] [33]
The Etruscan shrew has a very fast heart beating rate, up to 1511 beats/min (25 beats/s) and a relatively large heart muscle mass, 1.2% of body weight. [3] The fur color on the back and sides is pale brown, but is light gray on the stomach. The fur becomes denser and thicker from fall through the winter. [8]
[25]: 558 Like the hearts of vertebrates, the hearts of these animals have two separate states: a state of contraction known as systole, and a state of relaxation known as diastole. [25]: 558 At the beginning of systole, blood leaves the heart through a large artery known as the aorta and numerous arteries parallel to the heart.