Monday, August 29, 2016

Soil Centipede



No insect is safe from capture now that the WOLF School is back in session.  At our first meeting today there were cicada, bagworms and this tiny centipede which McKenna brought in from a recess hunt.  It was 3" long and very delicate.

It moved slowly like a millipede but without the wavelike motion of the legs.  Without magnification I couldn't tell if there was one or two pair of legs per segment.  We talked about the difference between millipedes (two pair of legs per segment) and centipedes (one pair of legs per segment.)  This is a soil centipede in the order Geophilomorpha.  There are 1,100 species identified world wide.

Geophilomorpha (GM) are extremely skinny, an important trait for a centipede hunting through narrow spaces in the ground substrate.  This order has species with 27 to 191 pairs of legs - our specimen has 56 pairs.  Unlike other centipedes that are built for speed, they move slowly through the soil by their legs and their ability to contract and elongate the body like the earthworms they hunt.

Fangs and antennae with 14 segments - REK
Back legs are antennae!
Like all other centipedes they are predators, eating earthworms, snails and small arthropods.  They lack eyes which would be worthless underground anyway.  They "see" the world through their antennae which are in 14 segments.  Their back legs are modified into antennae as well.

Earthworms are GM's specialty, captured with their fangs that inject venom.  They chew them up with small mandibles which have ducts secreting digestive juices, its enzymes digesting the food before taking it in.  If that sounds disgusting, recall that they are eating a worm.

Dorsal view of eyeless head
Their underground courtship begins with mutual tapping of antennae.  The female guards her eggs in the soil until the miniature GMs appear, looking just like the adults that they will become after several morphs.

 More details are at lucidcentral.org.

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