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133 votes
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Why is the heart not in the middle of the body?

First of all, let me make it clear that the heart is at the vertical centre of the body -- it is not shifted towards left (or right). However, it is slightly tilted towards the left in most cases. ...
another 'Homo sapien''s user avatar
78 votes
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How come large herbivores have such thin legs?

Elephant, rhinoceros, &c all have much thicker legs in proportion. The answer, I think, lies in the fact that the animals you mention all evolved as cursorial animals (that is, they run to escape ...
jamesqf's user avatar
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59 votes

Do "shooting" animals exist?

A good exemple should be the “harpoon” in cone snails (Conidae), which is created from a modified tooth inside their proboscis. (Cone snail with proboscis, from KQED.org) The harpoon is launched at ...
fileunderwater's user avatar
53 votes

How come large herbivores have such thin legs?

This is a mistake in comparative anatomy which is somewhat common. When looking at four-legged animals, people often mistakenly map the parts of the hind legs. Here is an image that shows the ...
user151841's user avatar
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39 votes
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How did the cardiovascular system evolve?

While others have addressed the big picture aspects of your question, I think it would be useful to look at the specifics. Have a look at the heart (or more accurately, the hearts) of the earthworm: ...
user151841's user avatar
  • 1,407
32 votes
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Does the octopus have an anus? What does it look like?

The anus of Octopus is channeled into its siphon. Image taken from Carina M. Gsottbauer Note: Siphon is a tube that leads from the mantle to the outside. Octopuses use their siphon to force water ...
Tyto alba's user avatar
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25 votes
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Is C. elegans always observed with precisely 302 neurons? Are there ever individual viable exceptions?

According to the highly respected WORMATLAS: A Database of Behavioral and Structural Anatomy of Caenorhabditis elegans, the number is invariable in this animal, one of the most studied in the world. ...
anongoodnurse's user avatar
23 votes

Where can I find the list of all tendons in the human body?

Your best bet is the Terminologia Anatomica, which is the international standard for anatomical terminology. The 1998 edition is freely available. It lists only a few named tendons though, which is ...
kmm's user avatar
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21 votes
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What is the anatomical term for a two jointed leg?

Welcome to Biology.SE! I think you are talking about plantigrade, digitigrade and unguligrade. Please note that the number of joints in mammals does NOT vary, but only the relative length (and shape)...
Remi.b's user avatar
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21 votes

How come large herbivores have such thin legs?

How come large herbivores have such thin legs? They don't. The following book does an extensive comparison of the bones of humans with other animals: Adams BJ, Crabtree PJ. 2008. Human vs Horse. In: ...
canadianer's user avatar
  • 17.8k
21 votes

Do "shooting" animals exist?

An excellent example (unless you consider this a tool) of a weapon using animal would be the "web casting spiders" which are a diverse group of spiders known as the Deinopidae. These spiders ...
bob1's user avatar
  • 12.5k
17 votes

Do "shooting" animals exist?

Although not a hard projectile the Archerfish shoots water https://en.wikipedia.org/wiki/Archerfish
Tristanisginger's user avatar
14 votes
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Using anatomical terms for human organs and parts of plants

First, for reference, see here for a discussion about the difference in directional terms between bipeds and quadrupeds as well as a fairly complete explanation of word meanings/etymology. The ...
theforestecologist's user avatar
14 votes
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Dorsal vs Posterior and Ventral vs Anterior

Short Answer This page on wikipedia gives a good synopsis of these concepts. The confusion lies in the fact that many websites on anatomy discuss/describe/define these terms in relation to humans. ...
theforestecologist's user avatar
12 votes

How did the cardiovascular system evolve?

This kind of question was raised in a book called "Darwin's Black Box" by Michael Behe, who is a biochemistry professor in the U.S. - he calls this 'irreducible complexity' (IC). For example, the ...
gilleain's user avatar
  • 890
12 votes

Where can I find the list of all tendons in the human body?

The FMA lists 705 tendons, but note that it includes separate terms for left and right instances. As @kmm says, many of these simply shadow the list of skeletal muscles (and is likely incomplete). ...
cmungall's user avatar
  • 291
11 votes
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What is the rest state for eyelids - Open or Closed?

This depends to some extent on how you define "resting state" (it matters). Innervation of the eye occurs in the brainstem and upper spinal column, so is, like most brainstem functions, on autopilot ...
anongoodnurse's user avatar
11 votes

Is C. elegans always observed with precisely 302 neurons? Are there ever individual viable exceptions?

Many Nematodes do not use traditional hox genes instead the have a strange set up which controls cell placement directly. This means individual adults of many nematode species have the exact same ...
John's user avatar
  • 14.7k
11 votes

Can birds touch their wing tips together either in front or behind (not above and below)?

Black herons (Egretta ardesiaca) can overlap their wing tips in front of them while doing what is known as canopy feeding.
tyersome's user avatar
  • 5,598
10 votes
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Can defibrillation be done with a car battery?

In general, no, but it is theoretically possible. Car batteries are designed to provide a large amount of amperage, to turn the starter with a high amount of torque via an electric motor. Generally ...
10 votes
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Can you tell if a corpse was male or female by only examining its skull?

According to textbook of forensic medicine and toxicology by Ks Narayan reddy: Qualitative differences are: Male mandible has everted ramus, but female have inverted ramus. Males have chin U shaped, ...
JM97's user avatar
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10 votes
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Why is Heart Rate Recovery after exercise reasonably well described by a mono-exponential decay?

I think most people would take exponential decay in a circumstance like this to be the null hypothesis. That is, if you had something not exponential decay, that would be curious and interesting and ...
Bryan Krause's user avatar
  • 46.1k
8 votes

Why is the opposite of plantar flexion called "dorsiflexion"?

Although the other 2 answers are accurate and well thought out, I just wanted to answer this with a bit different focused response. Two things to note: In general, one should think of flexion as ...
theforestecologist's user avatar
8 votes
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When is an anatomic entity named "laterale" vs. "lateralis"?

This is actually much more of a lesson in Latin linguistics/grammar. The root, Lateral, comes ultimately from latus meaning “side" or "flank” in Latin. [Source]. By adding one of these ...
theforestecologist's user avatar
8 votes
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Can frogs see clearly under and above water?

Short answer Frogs are nearsighted on land and farsighted under water. Background Frogs are reported to be nearsighted on land, but farsighted underwater (source: Chegg Study). Nearsightedness (...
AliceD's user avatar
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7 votes
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Coracoid vs. Coronoid - Etymology/Naming Choice?

It appears that both naming conventions originate with Galen, the Greek physician, almost 2000 years ago (for example, see: Singer, 1952). Although the precise motivations behind the naming ...
Bryan Krause's user avatar
  • 46.1k
7 votes

True anatomical/physiological explanation for "metaphysis" etymology

meta-: word-forming element of Greek origin meaning 1. "after, behind; among, between," 2. "changed, altered," 3. "higher, beyond;" from Greek meta (prep.) "in the midst of; in common with; by ...
Jan's user avatar
  • 8,089
7 votes

What are the upper and lower sets of teeth are called?

Upper teeth: maxillary teeth Lower teeth: mandibular teeth The term, "maxillary", is given to teeth in the upper jaw and "mandibular" to those in the lower jaw. If you search these terms you ...
WYSIWYG's user avatar
  • 35.6k
7 votes

Is the 6th rib attached to 7th rib, and 7th rib to 8th?

Those are just a part of the costal cartilage, which is only found at the anterior ends of the ribs, providing medial extension. This connects the ribs to the sternum and is made of hyaline cartilage. ...
Bipasha's user avatar
  • 964
7 votes
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Scientific terms for front-brain, mid-brain and back-brain

Since you are working with 3D data, why not segment them into lobes? You have 4: frontal (front), occipital (back), temporal (lateral middle) and parietal (top middle) lobes. If you really must have ...
S Pr's user avatar
  • 6,272

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