"Just how big do they get,
anyway?" Well, here's the biggest one
Mark found on his expedition to French Guyana in 2002. It's kind of hard
to tell how long it is, because it's in the midst of something called
"shortening." Like all soft-bodied animals, leeches have two types
of muscles in their body walls—an outer circular layer and an inner
longitudinal layer. When it moves, the leech elongates its body by contracting
the circular muscles, then "shortens" it by contracting the
longitudinal muscles. Its muscles are also ideal for swimming. Anyway, to be up front with you, this isn't as large as they get, not by
a long shot.
