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.
...
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79
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 ...
- 3,633
60
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 ...
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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 ...
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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 ...
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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.
...
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24
votes
Why are there no known animals with an odd number of legs?
It depends what you mean by 'leg'.
The instinctive way to define a 'leg' is based on its functional use: we use legs to walk on. But if we adopt that definition of 'leg' then there certainly are ...
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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 ...
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22
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 ...
- 11.2k
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)...
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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: ...
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18
votes
Why do adult insects have 6 legs?
Short answer
Six legs allow for locomotion, while maintaining a supportive tripod at all times.
Background
There are several million species of insects, all on 6 legs. This implies that any change in ...
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17
votes
Do "shooting" animals exist?
Although not a hard projectile the Archerfish shoots water
https://en.wikipedia.org/wiki/Archerfish
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16
votes
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Examples of animals with 12-28 legs?
As a couple of counterexamples, species in the classes Symphyla (Pseudocentipedes) and Pauropoda within Myriapoda have 8-11 and 12 leg pairs respectively, so between 16 to 24 legs (sometimes with one ...
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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 ...
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13
votes
Why are there no known animals with an odd number of legs?
Short answer
The body plan of terrestrial organisms that feature limbs is typically bilaterally symmetric, and hence these organisms have an even number of appendages.
Background
Terrestrial animals ...
- 52.3k
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).
...
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11
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. ...
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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.
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10
votes
Accepted
Can defibrillation be done with a car battery?
In general, no.
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 this is done at 12 or 24 volts.
...
10
votes
Accepted
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 ...
- 24.7k
10
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 ...
- 14.3k
10
votes
Accepted
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 ...
- 44k
9
votes
Accepted
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, ...
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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 ...
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8
votes
Why are there no known animals with an odd number of legs?
The other part of the question has already been amply answered, so I will concentrate on the part of the question which asks about "doesn't divide into odd numbers"
The assumption that organisms must ...
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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 ...
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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 (...
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7
votes
Accepted
Is the prostate problem unique to humans?
Dogs get benign prostatic hypertrophy, so, yes, other animals (in fact most old male dogs, so that would mean a whole lot of other animals) do get BPH.
The most common conditions affecting the ...
- 24.7k
7
votes
Accepted
Why do snakes not have eyelids?
Snakes have no eyelids. Each eye is covered with a single, transparent scale. These eye scales protect the eyes from mechanical damage, and prevent the eyes from drying out, just as an eye lid would ...
- 52.3k
Only top scored, non community-wiki answers of a minimum length are eligible