88

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 & Millsopp 2009). Long Answer There have been numerous studies that have documented behavioral lateralization in many groups of animals including lower ...


57

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 unconsciousness, let alone death. Parkes says: Breath‐holding is a voluntary act, but normal subjects appear unable to breath‐hold to unconsciousness. A ...


55

There are some cases, as hinted at by the comments. But these are relatively small amount of metal. Its not that there is no metal available, but I can think of several reasons you don't see iron exoskeletons on animals all the time. Firstly, fully reduced (oxidation state 0) metal has a high energetic cost to create in reduced form. Iron is the ...


55

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. However, there are animals other than mammals that produce milk-like substances to feed their young. Background Both male and female pigeons (Columba livia) ...


49

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. Gills collapse on land because of the lack of buoyancy (source: UC Santa Barbara). Octopuses have three hearts. Two of these are dedicated to move blood to the ...


49

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 is about 1000 mOsm/l (Wikipedia), but it can vary substantially between different seas, namely between 642 and 1,480 mOsm/kg (Ninawe & Banik, 1998). ...


35

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 fingers are wrapped around a large cable, most adults will be able to let go with a current of less than 6 mA. At 22 mA, however, more than 99% of adults will ...


35

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 service I became friends with some U.S. Navy SEALs. They go through a notoriously difficult training and selection process (BUDS) that has been well documented. ...


35

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 tissue, glands...): 19% Basal metabolic rate by 1 kg of specific organ tissue (kcal/kg of organ/day) (Table 5 from American Journal of Clinical Nutrition, 2010): ...


30

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 receptor reacts just like when you are exposed to cold (Bautista et al., 2007). The receptor is strongly activated at temperatures below 26 degrees Celsius (...


28

Before I restrict the answer to human metabolism, I recon it is important to mention that CO2 is the source of the carbon atoms of glucose in photosynthesis (in the Calvin cycle). [In photosynthesis CO2 is 'fixed']. Even with the above restriction, I am certain I cannnot do justice to every helpful aspect of CO2 in mammalian metabolism, and I'll restrict ...


28

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 independently from the evolution of mammalian milk, they are not considered to truly be milk.


27

Coscinasterias calamaria, the Eleven-Armed Sea Star! (Although I doubt it has much to do with pi) Image from Wikimedia Commons


26

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 dead wombats to investigate this question further. They found that varying degrees of pressure in the latter portion of the wombat's intestines (in conjunction ...


25

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. The effects of dangerous situations on the skin have to do with hormonal effects on the blood vasculature, and not with direct effects on red blood cells. ...


24

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: sodium and potassium. The concentration of sodium-ion in sea-water is about 450 mM, whereas the concentration of potassium-ion is only about 10 mM (ref) The ...


23

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 to support the statement that modern humans are "wimps" is a study of ancient fossilized footprints from Australia, which claim that the individuals making the ...


22

Short answer, your eyelids does not block all light. Since they are only a thin layer of skin, the light is able to pass through although not completely obviously. Since the eyes are still completely functional when you close them, only covered by the eyelids, you are able to see when light strikes your face.


22

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 Is this the video you saw? These images are pretty cool. Is this even possible? Yes (given that it exists). There is no way to correctly answer this ...


21

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 and is originally a glucose syrup. Since fructose is obviously much sweeter, the glucose is converted enzymatically into fructose (see here for more details). ...


20

A few minor points to add to shigeta's excellent answer: Biological enzymes don't work well on metals. Some often incorporate metals (see chelation) but elemental atoms aren't easy to process. For one, a large molecule would be identical everywhere, so cleavage, for example, would be indiscriminate and just leave a bunch of tiny tiny atoms. More to the ...


18

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 the body. Breathing is a part of physiological respiration and functions to bring oxygen into the lungs and expel carbon dioxide. Cellular respiration is a ...


18

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 plain text files, each with one line per species (plus header line) and fields separated by tabs. The files and data descriptions are available at http://esapubs....


16

There are good reasons why tissues/structures with a very high metal content might cause problems (I defer to the other answers here). However, I am aware of one other example: some molluscs incorporate high concentrations of iron into the points of the radula (basically a ribbon of teeth, used for grazing). This is especially important for grazing molluscs,...


16

There are two reasons for light to appear red through the eyelids. Eyelids get a rich supply of blood which contains iron (in hemoglobin). The iron in blood absorbs all colors of light but reflects red light. (reference) Our tissue transmits red wavelengths of light very well, but it doesn't transmit blue or wavelengths of light towards the blue end of the ...


16

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 is that you basically reset the heart to a blank state so you can start normal CPR procedure to help the heart go back to a normal rythm. That's why you see ...


14

First, "premature ejaculation" is a matter of definition. Here is an authoritative source. From the American Urological Association's news site, a 2008 notice: 'The ISSM [Int'l Soc. for Sexual Med.] has defined premature ejaculation as “a male sexual dysfunction characterized by ejaculation which always or nearly always occurs prior to or within about one ...


14

Yes, they do. The ovaries produce both testosterone and estrogen. Relatively small quantities of testosterone are released into your bloodstream by the ovaries and adrenal glands. Sex hormones are involved in the growth, maintenance, and repair of reproductive tissues [1]. The serum testosterone level in women with no acne, hirsutism, or menstrual ...


14

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 with spinning around is called "vertigo". From wikipedia: Repetitive spinning, as in familiar childhood games, can induce short-lived vertigo by disrupting the ...


Only top voted, non community-wiki answers of a minimum length are eligible