Re: are all invertebrates cold blooded

Hello Carlos -

Yes, all invertebrates are what is often referred to as "cold blooded."  
However, their blood is not really cold, just not as warm as "warm 
blooded" animals in most cases.  A more appropriate term for "cold 
blooded" would be ectothermic (ecto = outside) because their body 
temperatures are highly dependent on the environment which is outside of 
the body.  This is why critters like reptiles get sluggish when it gets 
cold - they do not have the ability to keep their bodies warm like we do 
as mammals.

The only classes of animals that are "warm blooded" are the birds and the 
mammals.  The better term for "warm blooded" is endothermic because these 
organisms control their body temperatures from within (endo = inside).

Thanks for your question!

Sue


Admin note:

Animals vary in their ability to control their body temperature.  Contrary to 
popular belief, many insects can control their body temperature.  Bumblebees, 
for example, maintain temperatures above 37 degrees even in cold weather.  "Cold 
blooded" and "warm blooded" are useless terms because the body temperature of 
an animal will vary according to its behaviour.  Bats, for example, may have a 
body temperature only a few degrees above zero when they go into hibernation.  
They need to maintain this low temperature to ensure that they survive on their 
fat supplies during the winter. However, they maintain a high temperature during 
the summer when they need to be active.

Richard Kingsley