90 votes
Accepted

Do animals exhibit handedness (paw-ness?) preference?

Short Answer Yes. handedness (or Behavioral Lateralization) has been documented in numerous vertebrates (mammals, reptiles and birds) as well as invertebrates. This includes domestic cats (see Wells ...
58 votes
Accepted

Why can't we kill ourselves by holding our breath?

Short answer Healthy people cannot hold their breaths until unconsciousness sets in, let alone commit suicide. Background According to Parkes (2005), a normal person cannot even hold their breath to ...
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56 votes
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Are there any non-mammalian species known that lactate?

Short answer Technically, only mammals lactate. To lactate means to produce milk from the mammaries to feed a baby or young animal. Milk, in turn, is defined as the secretions from mammary glands. ...
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50 votes
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Does animal blood, esp. human, really have similar salinity as ocean water, and does that prove anything about evolution?

Short answer Early sea water had a very different osmolality than blood plasma. Background The reference range of serum osmolality is 275–295 mosm/kg (mmol/kg) (MedScape). The osmolarity of sea water ...
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49 votes
Accepted

How long can an octopus survive out of the water?

Short answer Under ideal conditions, an octopus may survive several minutes on land. Background Octopuses have gills and hence are dependent on water for the exchange of oxygen and carbon dioxide. ...
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37 votes
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Why does an electrical shock freeze up muscles?

Interesting question! An important factor here is the let-go phenomenon, which is defined as the current level in the arm that will cause the hand to involuntarily grip the current source. When the ...
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36 votes
Accepted

What is the human energy consumption by organ?

Percent of basal metabolic rate by organ (BC Campus Open Education): Liver and spleen : 27% Brain: 19% Skeletal muscle: 18% Kidneys: 10% Heart: 7% Other tissues (lungs, intestine, skin, bone, fat ...
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35 votes

Why can't we kill ourselves by holding our breath?

Counterexample: At least some people can train themselves to hold their breath until they pass out, and if this occurs underwater they will almost certainly die by drowning. When I was in military ...
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30 votes
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Why do mints make your mouth feel cold?

The feeling of cold from mints is caused by menthol. Menthol affects the TRPM8 receptor on skin and also in the mouth. TRPM8 is also a general cold receptor: so if you are in contact with menthol the ...
  • 2,878
28 votes

Are there any non-mammalian species known that lactate?

Producing milk, per se, is a strictly mammalian phenomenon. There are functionally similar processes in non-mammals (e.g., 'crop milk', produced by some birds), but because these processes evolved ...
  • 3,294
27 votes

Does animal blood, esp. human, really have similar salinity as ocean water, and does that prove anything about evolution?

The argument that blood plasma resembles sea-water, in essence, relies on the notable similarity in concentration of two ions in plasma and sea-water, compared with their intracellular concentration: ...
  • 4,638
26 votes

Why is wombat scat (feces) shaped like cubes?

I'm almost certain that your question is based on the press that Patricia J Yang's research is receiving (e.g., here and here). Yang and her co-authors examined the structure and mechanics of some ...
25 votes
Accepted

Why does the face turn pale in dangerous situations?

Red blood cells are not equipped with a motor system to propel them through the blood stream. Instead, they are passively transported through the vasculature by the the pumping action of the heart. ...
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23 votes
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How fast can a human run?

An older answer that referred to the physiological feats of ancient humans, and why modern humans are wimps made me look up a couple of papers on running speeds a while ago. One of the examples used ...
22 votes
Accepted

Can an organism exist as a single cell but come together as multi-cellular during certain times?

Welcome to Biology StackExchange. Am I remembering this incorrectly? No, you're remembering it correctly. I think you're talking about slime molds. You'll find more information on the wiki page ...
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21 votes

Why is high fructose corn syrup unhealthy?

Besides a lot of propaganda there is not much evidence that high fructose corn syrup (HFCS) is more dangerous than normal sugar. Lets have a look at the sugar in detail: HFCS is produced from corn ...
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18 votes
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How can we differentiate between respiration and breathing?

There are two uses of the term respiration: physiological respiration and cellular respiration Physiological respiration involves the intake of outside oxygen and its distribution to the tissues of ...
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18 votes

Public database of animal specifications

You might be interested in the PanTHERIA database for several thousand mammalian species. It has up to 53 characteristics for each species (but many fields have no entry). It is available as two ...
  • 8,759
15 votes
Accepted

Why is defibrillation in asystole ("flat line") useless?

In layman's terms: an Asystole is not affected by the electric shocks of a defibrillator. A defibrillator is used when the heart goes in fibrillations because it actually CAUSES an asystole. The idea ...
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14 votes

Why are there no organisms with metal body parts, like weapons, bones, and armour? (Or are there?)

Well there is the common Bloodworm (Glycera dibranchiata)which people use for fishing bait. The animals are unique in that they contain a lot of copper without being poisoned. Their jaws are unusually ...
14 votes
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Do snakes get dizzy?

Probably don't do any experiments that involve shoving reptiles in a sack and swinging them around your head, as someone will surely call the ASPCA on you. The type of dizziness that is associated ...
  • 3,751
14 votes
Accepted

Why doesn't HDL cause diseases like LDL?

Thank you for the fascinating question! It was tough to research but very worthwhile. LDL is actually not such a bad molecule. It is formed from VLDL/IDL after VLDL/IDL distribute triglycerides, ...
  • 1,634
14 votes
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Why do people in the scientific community use terminology such as renal, hepatic, cardiac instead of kidney, liver and heart?

Medicine is not my field, but I want to point out two things: The former words have latin (or greek) roots, and historically latin was the international language of science. Therefore, nomenclature ...
14 votes

Why does a fetus drink and urinate into the amniotic fluid?

In utero, the growing little human is getting ready to be an independently functioning individual. While it is everything but that, it must be able to obtain fluids and nutrients through its mother's ...
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14 votes

Can mosquitoes be attracted by our voice?

Mosquitoes can hear the human voice. If they use human sound to hone in on us as a source of a blood feed is not known at this time, however research into this has just begun. This is especially ...
13 votes

Why are there no organisms with metal body parts, like weapons, bones, and armour? (Or are there?)

Looks like some parasitoid wasps have zinc coated barbs on their ovipositors which may function to help them bore through wood and lay their eggs. Here's the blog entry about it on IFL Science, and ...
13 votes

Why does an electrical shock freeze up muscles?

When the body comes in contact with an electrical power supply, two things can happen. If the current flow is high enough, the body heats up just like a heating resistor, and opposed to the resistor, ...
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13 votes

Why does the affinity of haemoglobin for oxygen decrease at high altitudes?

The answer to this question is yes, a decrease in oxygen affinity will decrease the oxygen taken up by the haemoglobin (Hb), but it is an appropriate response because it will have a greater effect in ...
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13 votes

Public database of animal specifications

I'm not positive, but I assume you'll be hard-pressed to find a list that checks your boxes of needing both multiple metrics for multiple animals. However... Two sources that seem to prove me wrong:...
12 votes

Do snakes get dizzy?

Dizziness is caused by a continuing rotation of the fluids in the semi-circular canals of the vestibular system that transmit rotation information to the brain. After prolonged rotation of the body, ...
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Only top scored, non community-wiki answers of a minimum length are eligible