The study of the internal structure of organisms.

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is left brachiochephalic vein and left pulmonary artery is same?

I am reading about ligamentum arteriosum which connects the left pulmonary artery and descending aorta. But I am seeing that if any figure shows left brachiochephalic vein it does not show left ...
2
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0answers
44 views

Differing number of “things” in mammals [closed]

I'm not a biology expert, but I have often wondered about the following facts of life: All mammals have precisely 5 fingers on each of our 4 extremities. Granted, some may not be seen, but the bone ...
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0answers
19 views

Bolyerine Snakes maxillary bone, split?

How is the maxillary bone split in the Bolyerine Snakes described in T.H Frazzetta's "From Hopeful Monsters to Bolyerine Snakes?" In T. H. Frazzetta, "From Hopeful Monsters to Bolyerine Snakes?" He ...
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2answers
95 views

Horns in animals and birds [closed]

Are there any carnivores with horns (whether extinct or currently alive)? Do any flying creatures have horns? By horns I mean horn like structure.
2
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1answer
42 views

Serious question about a piece of meat

Does anyone know some scientific rigorous way to look at a slice of meat. I am not asking what kind of meat it is or which part of the animal it came from. I wonder what is the different lining on ...
5
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1answer
41 views

Stretching and compressing bones

The Young's modulus of elasticity when a bone is stretched is : 16×109 and when it is compressed, it is 9×109 N/m2. That means, change in length will be more if you compress a bone as compared to ...
2
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1answer
23 views

By what method do ants dissect and hold soil

Not sure if this is the correct stackexchange site - please migrate/advise as you see fit. I'm interested in the method by which ants "break off" a small amount of soil and then hold it in their jaws ...
3
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1answer
113 views

How do cats survive falling from great heights?

Among mammals, cats are able to land safely when falling from great heights. For example, when compared to dogs or humans they can survive drops from relative large heights. How do they manage? A ...
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1answer
34 views

Does the size or mass of a body affect the time it takes for rigor mortis to sets in?

Does the size or mass of a body affect the time it takes for rigor mortis to sets in? For example: compare a 300 pound man to 100 pound girl to 5 pound animal.
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1answer
119 views

Can humans live without their right atrium?

The right atrium is one of four chambers (two atria and two ventricles) in the hearts of mammals (including humans) and archosaurs (which include birds and crocodilians). It receives deoxygenated ...
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3answers
564 views

How many cells does the smallest animal have?

Note: question rewritten to prevent misunderstanding and make it more answerable I know that some small animals like C. elegans display surprising sophistication with a very small number of cells. ...
0
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1answer
11 views

Relation between trigeminal and facial nerve in sympathetic response

In my neuro-anatomy course notes I found that the facial nerve "uses" the trigeminal nerve to reach its targets. However, I have yet to find any diagram or reference that indicates how this is done. ...
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0answers
19 views

Terrestrial Vertebrate Limbs

This question is regarding the conversation that took place here: Why don't mammals have more than 4 limbs?. I'm not sure if someone mentioned this and I just missed it, but everyone is talking ...
3
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2answers
332 views

Why do we have to exhale (or inhale) in order to speak?

Every time we speak, sing, or make any other kind of advanced noise with our throats, we exhale, or to put it that way, blow air through our throats. Why is this required? After all, speakers do not ...
6
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1answer
133 views

Why do some internal organs regenerate?

I have been reading about the human liver and zebra fish heart muscle having the ability to regenerate. It seems to me that these organs have very little chance to become damaged or worn out. At the ...
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1answer
39 views

The suspended cat clavicle

I know the clavicle of the cat floats freely as opposed to be attached as in humans. This is supposed to allow them to be able to squeeze through spaces, according to a quick google search. But how ...
4
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1answer
54 views

Comparative leg sizes

When I was a child, my father showed me the classic essay "On Being the Right Size", J. B. S. Haldane. It talks (among other things) about how large animals need stockier legs to support their ...
2
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1answer
36 views

Why is the vermis of the cerebellum associated with speech?

I've found multiple sources claiming that damage or impairment as a result of alcohol to the vermis of the cerebellum results in speech impairment. I find this a bit surprising, since the only areas I ...
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1answer
19 views

Lateral corticospinal tract and termination

I'm studying the motor pathways of the brain and I'm a bit confused about how the lateral corticospinal tract descends. From Neuroanatomy: Text and Atlas by ...
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0answers
37 views

Why are there no animals with a length greater than 30-40 meters or with a mass greater than 200 tonnes? [duplicate]

The biggest and heaviest aquatic animal is the blue whale: 30 meters long and a mass of 200 tonnes. The biggest and heaviest terrestrial animal was a Sauropod (plant-eating, long-necked dinosaur): 40 ...
5
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2answers
140 views

Why do small organisms make faster movements than big organisms?

I hesitated to ask this question because it seems so obvious and intuitive. However, I am not able to explain this tendency. Background It seems to me that small organisms make faster movements than ...
6
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1answer
172 views

What are the atmospheric requirements for large dinosaurs?

What are the atmospheric requirements for large dinosaurs? and are the atmospheric constituents for supporting large dinosaurs any different from the atmosphere today?
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2answers
58 views

Periodic Muscular Growth in Humans

If a healthy human is at a certain muscle state and then experiences muscular atrophy solely due to disuse/lack of exercise, is it easier to gain that muscle back than if the human had never reached ...
5
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1answer
590 views

Why does the sacrum fuse together?

Everywhere I look describes how the 5 sacral vertebrae start fusing together during adolescence and are totally fused by the time you're 30 or so. But nobody seems to explain why this happens. It ...
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0answers
66 views

Total number of pleura in the exoskeleton of cockroach

Basically as far as i know cockroach consists of 10 terga and 9 sterna but what are the total number of pleura present in the cockroach. Pleura are situated between tergum and sternum of a body ...
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1answer
50 views

What is the smallest known organism with a skeleton? [closed]

See question title. After doing some looking around on my own I haven't found much so I figured I'd ask some experts.
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3answers
2k views

Which organs do cats not eat on their prey?

My female cat is a very active hunter and brings me her prey daily. Except for shrews and birds, she always eats them entirely. This afternoon she brought me this: It was quite large (maybe ...
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1answer
275 views

Identifying structures from anterior end of dissected prawn

Note: This image might be disturbing. I want to know what the red and the black structures (directly posterior to the red structure) are. I guess it's the heart.
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1answer
782 views

Identifying internal structure of dissected prawn

Note: Some of the images might be disturbing. I have dissected prawn for the first time. Would like your help in identifying some structures . This is the dissection of the posterior part of the ...
3
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1answer
104 views

Identifying internal structures of dissected fish

Note : Images displayed below might be disturbing to some people. I have dissected a fish for the first time ! I have some idea of what some of the structures might be but I am not sure and so would ...
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1answer
34 views

Why rectus abdominis is not proximal muscle?

I am thinking this picture which shows proximal muscles. Why for instance pectoralis major, subclavius and rectus abdominalis are not included in proximal muscles?
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1answer
188 views

Raising two legs together while lying on bed

Let's do some exercise(duh!) Ok so lie on the bed. Lift your left leg. Put it down. Lift your right leg.Put it down. Easy? Now lift your left leg and without putting it down, lift your right leg. ...
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1answer
85 views

Stomach sagittal section

Can anyone please tell me where is exactly the stomach in this image? This is a sagittal section from the University of Michigan Visible Human Browsers. Thank you.
6
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5answers
2k views

Why do most mammals have long snouts?

It seems like most mammals, e.g. dogs, have long snouts. My pet dog's snout would seem to me like an evolutionary disadvantage, since her canine teeth are way out at the end of her jaw, which acts as ...
6
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1answer
344 views

evolutionary reason behind sharing the same path for food and air?

What is the evolutionary reason behind sharing the same path for food and air? For example, we have a nose and lungs, yet they are linked by the pharynx, which is shared with the mouth and ...
2
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0answers
73 views

Where are the gastralia (stomach ribs) attached?

Crocodiles and some dinosaurs have a second set of ribs between the sternum and pelvis called gastralia. Where are the gastralia attached to the rest of the skeleton?
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1answer
437 views

Why do rodents' teeth continue to grow?

Why do rodents' teeth continue to grow? Enamel formation and/or root formation continue throughout rodents' lives. What's the mechanism that causes this?
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1answer
2k views

What determines the size and shape of a cell? [closed]

What determines the size and shape of a cell? They differ at different tissues / organs/ species
4
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1answer
72 views

Is there differences in components of saliva among species

Are there differences in the components of saliva among species? Also, do the functions of saliva differ between species?
0
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1answer
39 views

Can we remove impacted teeth by key hole surgery?

Can we remove impacted teeth by key hole surgery, rather than an open technique, like lithotripsy?
3
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1answer
376 views

Is there a difference between pig and cow anatomy that makes religious slaughter of the latter less painful?

This question is not for the squeamish. I was told that non-Kosher animals like pigs have a different anatomy in their neck compared to kosher animals like cows such that the Shechita method of ...
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2answers
97 views

Plant anatomy, what are these stem like filaments growing under the flower

The picture below shows what I am talking about. Each flower has one and I am just wondering what they are?
7
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1answer
396 views

What is the name of the appendage that mantis shrimp use to rub their eyes?

In this short clip, you can see the mantis shrimp using some sort of feathery arm/claw to rub its eyes. Looking at a diagram here, it appears possibly that it's using maxillipeds. Someone with ...
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1answer
1k views

Structure of adenoids

I am not sure this question belongs in biology, but I can't find a more suitable stack exchange site, feel free to delete it if this doesn't fit here. Also, this question is going to be slightly ...
1
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1answer
112 views

Is stereo olfactory ability restricted to humans?

Most animals I see around seem to have two nostrils - humans, snakes, birds, fish .. and so on. From reading online I see that 2 nostrils provide a stereo olfactory effect. This stereo effect is ...
5
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1answer
191 views

What limits the size of fish compared to marine mammals?

The largest extant fish species is the whale shark (Rhincodon typus). With a length of 13 meters and a mass of about 20-30 metric tons, the whale shark is relatively small compared to the largest ...
3
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1answer
75 views

What accounts for size variation in breeds of dogs?

My assumption is that dogs vary so much in size because of artificial selection pressures coming from human breeders, but are there genetic loci that roughly determine approximate size? Do other ...
20
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2answers
2k views

Why Is Most Life Symmetrical Externally But Not Internally?

Mammals, reptiles, arachnids, insects, etc are all as far as I am aware symmetrical in appearance. Take a human for instance, make a line from the top of our head right down the middle. However, ...
6
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2answers
8k views

Do other male mammals except for humans have nipples?

When I grew rabbits, I had a pair, one male and one female. And while the female's nipples were quite prominent, especially after giving birth, I don't remember the male having any nipples at all. Do ...
13
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1answer
271 views

Evolution of long necks in giraffes

In this question, the OP uses giraffe necks as a supportive example of evolution. Is the mechanism described in this post accurate? At some point, I thought I remember hearing that giraffes did not ...