The kimura-gumo (Heptalhela kimurai) is a spider, named after Kimura Arika, who discovered it in 1920. It belongs to the sub-order Liphistiomorphae (primitive burrowing spiders). Their burrows are covered by a camoflaged "pill box" cover.

For photographs of spiders and the entrance to their lairs, see http://www.asahi-net.or.jp/~vp6m-bn/001okinawa.htm

The spider is unusual in that it retains features which were probably typical of ancestral spiders, and which are no longer seen in other living spiders. Thus observation of this species can shed light of the development of all spiders. These ancestral features include the central spinnerets, and signs of segmentation on the abdomen.

The word kumo or gumo in Japanese generically means spider. The kimura spider is near 400 million years old and it is among the most primitive still living spiders. It has spinning glands in the middle of the body. This location is not very effective. It fixes its eggs on the surface with a cobweb, so they are well protected. The spider surrounds underground tunnels also with a cobweb. When it sets out on a hunt, it pulls the thread with it. This helps it in orienting itself.

References

1. Tomo Kočar, Strah je okrogel in ima osem nog (The fear is round and it has eight legs), GEA 12 (2002) 7, pp 46 - 49.
2. Yoshikura, M. 1982. Kumo no fushigi (The wonder of spiders). Iwanami-shoten, Tokyo.