Reply
 
Thread Tools Display Modes
  #1  
Old 09-19-2019, 08:04 AM
Steven Estes is offline
Guest
 
Join Date: Sep 2001
Posts: 180

Is an insect the smallest species that we can see with the naked eye?....


1. Is an insect the smallest species that we can see with the naked eye?
2. Are any insects too small for the naked eye to see.
3. What is the largest species the naked eye can not see.
  #2  
Old 09-19-2019, 08:18 AM
Machine Elf is offline
Guest
 
Join Date: Feb 2007
Location: Challenger Deep
Posts: 12,296
According to this source, the human eye can see objects that are around 50-60 microns across.

The smallest adult insect is Docopomorpha echmepterygis, which is 139 microns long. This answers question #2: there is no adult insect too small for the naked eye to see.

There's room between 50 microns and 139 microns for some other species to claim the prize for question #1. Strictly speaking, worms are not insects - and there is a nematode that measures in at 20 microns, too small to see with the naked eye. It's hard to search Google for "adult animal larger than 50 microns but smaller than 139 microns," but it seems very likely that such a creature exists.

#3 is likewise difficult to search the internet for, i.e. "adult animal slightly smaller than 50 microns."
  #3  
Old 09-19-2019, 08:27 AM
Alessan's Avatar
Alessan is online now
Guest
 
Join Date: Jul 2000
Location: Tel Aviv
Posts: 24,754
3. Mites.

Mites, which are a) not insects and b) basically everywhere, including on your skin right now, range in size from 6 mm to microscopic, which means that are probably plenty of them right at the limit of what we can see with our naked eyes.

Last edited by Alessan; 09-19-2019 at 08:30 AM.
  #4  
Old 09-19-2019, 09:04 AM
Qadgop the Mercotan's Avatar
Qadgop the Mercotan is offline
zymolosely polydactile
Charter Member
 
Join Date: Apr 2000
Location: Slithering on the hull
Posts: 27,394
Quote:
Originally Posted by Alessan View Post
which means that are probably plenty of them right at the limit of what we can see with our naked eyes.
You mean we mite see them, or we mite not?

Anyway, the human ovum is about 100 microns, so we can see that. A single human cell!

Last edited by Qadgop the Mercotan; 09-19-2019 at 09:06 AM.
  #5  
Old 09-19-2019, 09:15 AM
scr4 is offline
Guest
 
Join Date: Aug 1999
Location: Alabama
Posts: 16,087
Quote:
Originally Posted by Machine Elf View Post
According to this source, the human eye can see objects that are around 50-60 microns across.

The smallest adult insect is Docopomorpha echmepterygis, which is 139 microns long.
But how wide is it? If it's 139 microns long but less than 50 microns wide, it may not be visible. And judging from this photo, I think its width is less than 1/3 of its length.

Of course "can see with the naked eye" is a very poorly defined criterion. It depends on so many factors like color, lighting conditions, background, etc. Is it crawling on a leaf in the forest, or on a pure white surface in a well-lit lab? Not to mention the huge variation in human eyesight. People who are severely short-sighted (like me) can focus on something much closer, and therefore see smaller things.

Last edited by scr4; 09-19-2019 at 09:16 AM.
  #6  
Old 09-19-2019, 10:33 AM
Darren Garrison's Avatar
Darren Garrison is offline
Guest
 
Join Date: Oct 2016
Posts: 11,705
Quote:
Originally Posted by Machine Elf View Post
It's hard to search Google for "adult animal larger than 50 microns but smaller than 139 microns," but it seems very likely that such a creature exists.
Probably an amoeba that fits in the gap.
  #7  
Old 09-19-2019, 11:17 AM
mixdenny is offline
Guest
 
Join Date: Apr 2016
Location: Cleveland suburbs
Posts: 1,992
This brings up Mixdenny's Theorem #27. If you see something moving on your skin that you can barely see, chances are good that you do not want to look at it under a microscope.

Dennis
  #8  
Old 09-19-2019, 11:29 AM
squidfood is offline
Guest
 
Join Date: Nov 2006
Posts: 452
Plankton (i.e. in the ocean) are sorted and classed by size; e.g. "picoplankton" are anything 0.2 to 2 microns, "nanoplankton" are 2 to 20 microns, and "microplankton" are 20-200 microns. There's a table on that wiki link that list species groups each size class, so the range of species that cross the visual threshold might include diatoms, flagellates, etc. For a fish trying to eat these (I study some of this), visual acuity depends heavily on light, contrast, and shape, so I wouldn't want to pick a number as a threshold, but it's likely you could find a continuum of species crossing any limit in this range that you might set.
  #9  
Old 09-19-2019, 11:55 AM
Folly's Avatar
Folly is offline
Guest
 
Join Date: Aug 2004
Location: Chicago! (no more burbs)
Posts: 2,282
Tardigrades (water bears) range from 50-1200 microns.
  #10  
Old 09-19-2019, 12:28 PM
Alessan's Avatar
Alessan is online now
Guest
 
Join Date: Jul 2000
Location: Tel Aviv
Posts: 24,754
Quote:
Originally Posted by Qadgop the Mercotan View Post
Anyway, the human ovum is about 100 microns, so we can see that. A single human cell!
I had two large chicken cells for dinner tonight, myself.
  #11  
Old 09-19-2019, 12:44 PM
markn+ is offline
Guest
 
Join Date: Feb 2015
Location: unknown; Speed: exactly 0
Posts: 2,678
Caulerpa taxifolia is a single celled algae that looks remarkably like a plant. it has structures that resemble stems and leaves, and grows up to 12 in long, but it's all just one cell.
  #12  
Old 09-19-2019, 12:51 PM
Beckdawrek's Avatar
Beckdawrek is online now
Member
 
Join Date: Aug 2017
Location: So.Ark ?
Posts: 17,989
Quote:
Originally Posted by Alessan View Post
3. Mites.

Mites, which are a) not insects and b) basically everywhere, including on your skin right now, range in size from 6 mm to microscopic, which means that are probably plenty of them right at the limit of what we can see with our naked eyes.
I didn't need to hear that.
  #13  
Old 09-19-2019, 01:27 PM
Darren Garrison's Avatar
Darren Garrison is offline
Guest
 
Join Date: Oct 2016
Posts: 11,705
Sometimes I have something stroll across my phone screen that there is no chance I would have ever seen if it wasn't on a backlit uniform surface. They (whatever they are) are probably pretty close to the visibility limit.
  #14  
Old 09-19-2019, 01:51 PM
Limmin's Avatar
Limmin is offline
Guest
 
Join Date: Oct 2018
Posts: 152
Quote:
Originally Posted by Folly View Post
Tardigrades (water bears) range from 50-1200 microns.
...and thanks to the crashed Beresheet lander, Tardigrades have recently been spotted on the moon...
  #15  
Old 09-19-2019, 03:18 PM
Chronos's Avatar
Chronos is offline
Charter Member
Moderator
 
Join Date: Jan 2000
Location: The Land of Cleves
Posts: 85,139
The answers to 1 and 3 will be the same: If one individual of a species is just slightly above the limiting size, then there will be some other individual of the same species that's just slightly below the line. But there are many, many different species, of many vastly unrelated lineages, that are at that size scale.
  #16  
Old 09-19-2019, 04:38 PM
Buck Godot's Avatar
Buck Godot is offline
Guest
 
Join Date: Mar 2010
Location: MD outside DC
Posts: 6,017
Quote:
Originally Posted by Qadgop the Mercotan View Post
You mean we mite see them, or we mite not?
There's gotta be a Straight Dope rule against the flagrant use of weaponized puns outside the pit. If not there should be.
  #17  
Old 09-19-2019, 05:32 PM
Alessan's Avatar
Alessan is online now
Guest
 
Join Date: Jul 2000
Location: Tel Aviv
Posts: 24,754
Quote:
Originally Posted by Beckdawrek View Post
I didn't need to hear that.
Look, it's not as if there aren't billions of microscopic creatures on and in your body at any given time. So some of them are multi-cellular - what difference does it make?
  #18  
Old 09-19-2019, 09:20 PM
Spectre of Pithecanthropus is offline
Charter Member
Charter Member
 
Join Date: Aug 1999
Location: Transplanted!
Posts: 19,384
The ciliate protist Stentor is one of the largest unicellular life forms, and can reach two millimeters in length. So my vote would be for a not quite fully grown Stentor.

https://en.wikipedia.org/wiki/Stento...29?wprov=sfla1
__________________
Change your latitude, change your attitude.

Last edited by Spectre of Pithecanthropus; 09-19-2019 at 09:21 PM.
  #19  
Old 09-19-2019, 09:28 PM
jaycat is offline
Guest
 
Join Date: Nov 2014
Posts: 1,484
Quote:
Originally Posted by Limmin View Post
...and thanks to the crashed Beresheet lander, Tardigrades have recently been spotted on the moon...
And who said NASA was a waste of money!
  #20  
Old 09-19-2019, 10:12 PM
Darren Garrison's Avatar
Darren Garrison is offline
Guest
 
Join Date: Oct 2016
Posts: 11,705
Quote:
Originally Posted by jaycat View Post
And who said NASA was a waste of money!
Probably somebody who knows that NASA isn't an Israeli agency?
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 01:28 AM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, vBulletin Solutions, Inc.

Send questions for Cecil Adams to: cecil@straightdope.com

Send comments about this website to: webmaster@straightdope.com

Terms of Use / Privacy Policy

Advertise on the Straight Dope!
(Your direct line to thousands of the smartest, hippest people on the planet, plus a few total dipsticks.)

Copyright 2019 STM Reader, LLC.

 
Copyright © 2017