I have rediscovered a book, I have had lying around for ages, just gathering dust. It was given to me by Richard Michaels when I worked with him in a West London comprehensive.
First published in 1970 Invertebrates by M.A. Robinson and J.F. Wiggins is a the reference book packed with little nuggets of information and some odd facts about invertebrates that make you think.
For instance sea anemones only have one opening to their digestive tract. So in effect their mouth and anus are the same orifice!
Slugs are protandrous sequential hermaphrodites, which means that they are born male but develop a female reproductive system later, whilst keeping the male one too.
This lead me to look into the reproductive cycle of slugs and snails. Yes, I do not get out much! On my voyage of discovery I chanced upon this gem of a web page at the following blog:
Banana slugs are a real revelation!