Ask A Scientist© Biology Archive

Author:      library
Text:        How do worms see?  Can a worm still live if it gets cut in half?  
How does a worm reproduce?  How do worms eat?  How many different kids of 
worms are there?

Response #:  1 of 1
Author:      Jim Murray
Text:        Some worms are blind.  Some worms have eyes to see with.  Most 
worm eyes are simple pigment cup ocelli.  They usually have only a few light 
sensitive cells with pigment cells behind them.  That way the ocelli (little 
eyes) only detect the light that is in front of the worm.  Several types of 
worms can live if cut in half, some cannot.  The earthworms that you are 
likely familiar with can!  Worms reproduce in many different ways.  Earthworms 
are hermaphroditic, both male and female at the same time.  When they mate, 
each gives and receives sperm cells, and both have offspring.  But some worms 
have ones that are males only.  Again, worms eat in many different ways.  Some 
filter food out of water with mucus nets, others digest food out of soil, 
others have jaws and eat small animals, and leeches suck blood.  "Worm" is an 
ill-defined term.  There are several different groups of animals called worms.  
The Annelids include earthworms, polychaetes, and leeches.  There are 8700 
species of them described, and probably more to go.  There are 12000 species 
of flatworms and about as many nematodes worms.