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Why Streptococcus bacterias don't separate completely?

Why Streptococcus bacterias don't separate completely from each other? Is there any connection with this phenomenon and Fts proteins and related mechanism in cell devision?
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0answers
34 views

How does DNA organise a cell's physical position within a body?

How do cells "know" where they are supposed to be in relation to other cells, in forming the physical shape of the body? If you have ever tried to organise or choreograph the physical positions of a ...
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48 views

The Perplexing Trilobite: What is the Evidence Supporting The Hypothesis That They are Not Crustaceans?

In the field of paleontology, one question that's really bugged me (er, no pun intended) of late is why the subphylum/class Trilobitomorpha/Trilobita is off on its own branch of the Arthropoda phylum, ...
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2answers
41 views

Spatial dimensions for an animal

I'm reading a review paper. They say: The position of an object in head-centered coordinates (that is, relative to an animal's head) can be defined along three axes: the medio-lateral (radial) ...
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2answers
116 views

The alignment of fingers in our hand

I noticed that in my hand the index and middle finger are aligned in one direction and the next two fingers somewhat in the opposite direction. My question is, why are our fingers aligned in that way? ...
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21 views

How is this pseudopupil formed?

Pseudopupil is very common optical phenomenon generally arises due to compound eye structure and source of light. I can imagine normal dark spot on eyes on insect like this or this. But I was ...
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1answer
881 views

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

I am trying to remember a particular segment from a BBC special, in which there was single cellular species. However, at certain times all the individual cells came together to form a structure, not ...
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1answer
395 views

Measuring body size in flies/insects

"Mesothorax length (the distance from the tip of the scutellum to the most anterior part of the mesothorax)" From Bergland et al 2008. Would that be this distance (green line)? If not, how ...
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1answer
1k views

What is 'refractile' cell morphology?

I can't find a definition for 'refractile' (not 'refractory', and not explicitly in an optical context). As in: A tumour cell phenotype features increased proliferation, anchorage- and growth ...
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108 views

Phylogenetic method to detect shift in mean of continuous variable

I am currently working on a project where I study the change of a continuous morphological variable with body size (measured as body weight) across diverse taxa (insects, spiders, lizards, frogs). In ...
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1answer
70 views

How to determine externally that a whale is a mammal?

Mammals have external qualifying characteristics like body hair, ear pinna, etc. But a whale has none of that. So, can it be identified as a mammal just by external observations?
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2answers
2k views

Why do rabbits often have white hindquarters?

There are several species of herbivores that have a very visible white hindquarters: several kinds of deer, rabbits, antelopes, etc. Does the white fur serve a functional purpose, or is it purely ...
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1answer
2k views

List of Asymmetric Animals

The (male) Fiddler Crab is a famous example of an animal whose morphology exhibits neither mirror nor radial symmetry: (Image source) List of animals featuring external asymmetry is a Wikipedia ...
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2answers
200 views

Are there special constants in biology that define organism's morphology?

In math, there are special numbers, like Pi (3.14159...) and e (2.71828...). In chemistry, there's numbers like avogadro's number (6.0221413e+23). For example a circle can be defined in terms of 2 * ...
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3answers
2k views

Do animals exist with an uneven total number of digits?

I recently finished reading Contact by Carl Sagan. In the book they talk about a pattern in the transcendental number like pi or e, and comment that it is found in base 10 or however many fingers the ...
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2answers
188 views

Can any species be bred selectively/engineered to become as diverse looking as dogs?

I've done some research and it appears that dogs are the most diverse looking single species of mammals. The questions that interest me is - are dogs special in respect to genes/gene activation ...