|
The
King crab, or horseshoe crab, is not really a crab at all. In fact it is not
even a crustacean but a very primitive arthropod which belongs to a group
of its own. From fossil evidence we know that king crabs were abundant in seas
about 175 million years ago. The few species that survive today are
virtually unchanged from those early ancestors and for this reason they are
sometimes called 'living fossils'.
King crabs have some unusual features. They are about a foot across, have heavy
domed shell divided by a joint across, have a heavy domed shell divided by a
joint across the middle, four pairs of walking legs and a long spiky tail. The
bony mouth extends between the bases of the legs which help in chewing up the
food. These characteristics, together with their gills and mouthparts, tell us
that the King crab is actually descended from the forerunners of another group
of arthropods adapted for life on land-the arachnids. These include the
scorpions, spiders, mites and ticks, and daddy long legs or harvestmen.
Read more
Website of Facts Home
|
