Interesting invertebrates of KwaZulu-Natal

Fieldwork often results not only in important additions to the collections of the Museum, but in field observations as well.

Freshwater crabs, for example, are well known to live on land for many days, but we wouldn’t expect them to climb trees, would we? Nevertheless, they do. The female crab (see the photo), – Potamonautes sidneyi (Rathbun, 1904) was sitting more than one meter above the ground on the trunk of a pine tree and started to descend only when we tried to photograph her. And that tree was more than 400 meters from the nearest stream. Young crabs of this species spend most of their time under rocks in streams and in burrows next to streams, and can move significant distances from the water when they become adults.

Other interesting animals that inhabit our province and that we do not see too often are Onychophora. Despite their common name, velvet worms, they are not worms, but one of three surviving groups of diverse lobopodian marine animals that were quite common during the Cambrian era (about 500 million years ago). Onychophorans retained more overall similarities with their Cambrian relatives than the other two: minute aquatic Tardigrada (about half a millimeter in size with four pairs of stubby legs) and Arthropoda (with various number of segmented legs). The female of Opisthopatus cinctipes Purcell 1899 (see photo) has 16 lobopods (stub legs) and 30–40 mm in length. All onychophorans have a pair of slime glands next to their mouth and can spray slimy adhesive fluid a distance many times their own length. Normally they do that to immobilize their prey (medium sized arthropods), but can defend themselves using this behavior as well.