INSECTS
From butterflies to ants, beetles to bristletails, grasshoppers to flies, caterpillars to bees, praying mantids to termites – insects come in a spectacular array of shapes, sizes and colours.
The total number of named insect species lies between 800 000 and 1 000 000 which is about 55% of all known species on earth. The number of described species is a mere fraction of the real number, the total number probably exceeds 6 000 000.
Insects are the only invertebrates with 3 pairs of legs. They have a single pair of antennae and their bodies are divided into a distinct head, thorax and abdomen.
Insects are the only invertebrates to have evolved wings, although these are present only in adults. Most adults have 2 pairs of wings, but one or both pairs may be reduced or absent.
Insects are of enormous importance to the functioning of natural ecosystems and to the lives of humans. They are the most abundant macroscopic organisms in most terrestrial and freshwater habitats. However, they are almost completely absent from the sea, where they are largely replaced by crustaceans.
Predatory or parasitic insects control the density of many other life forms and also play a valuable role in regulating pest populations.
Insects are also primary plant pollinators and are instrumental in the completion of the life cycle of many plant species.
They are a huge food resource for birds and they also provide us with silk and honey!
The fynbos region
Fynbos has a unique group of insects and a large number are of considerable evolutionary interest. It has a high count of endemic species (ie. they are found only in the fynbos biome).
The nutrient poor, acidic waters of the fynbos region are stained brown by humic compounds and also support a distinctive insect fauna.
Ants play a unique role as distributors of seeds of certain fynbos species such as proteas. The ants are attracted to the seeds which have fleshy white appendages called elaiosomes. The seed is carried underground to ant nests, the fleshy elaiosome is eaten and the seed itself is discarded where it lies underground until conditions are suitable for germination.
SPIDERS
Spiders are found worldwide, up to 45 000 species, on every continent except Antartica.
Spiders have 8 legs, fangs that eject venom, an unsegmented abdomen with a group of spinnerets at the posterior end. They do not have antennae. They produce silk to make webs, snares, shelters and egg sacs.
They are predatory, mostly preying on insects and other spiders. They vary in size from less than 1mm to giants that may exceed 15cm.
Spiders of the fynbos region
Spiders can be largely divided into 2 groups: 'web-dwellers' - spiders that build webs to catch prey, and 'wanderers' - spiders that move around to ambush and catch prey.
Web spiders have poor vision relying on acute sensors to pick up vibration.
The best known web spiders are the Araneidae (Orb-web spiders) which are seen during the day. Their spun webs, which can sometimes reach more than a metre in diameter, are attached to fynbos plants. Hairy Field spiders (Neoscona sp.) make their orb-webs at night and hide during the day on plants.
Other web types found in the Reserve include Sheet-web spiders, (Linyphiidae), Gumfoot-web spiders (Theridiidae), Plant Mesh-web spiders (Dictynidae) and Ground Mesh-web Weavers (Phyxelididae).
Wandering spiders do not use silk to catch prey. Some are active on the soil surface, and include Wolf spiders (Lycosidae), Dark Sac spiders (Corinnidae) and Flat-bellied Ground spiders (Gnaphosidae).
Other wandering spiders live on plants and include Jumping spiders (Salticidae), small Running spiders (Philodromidae) and Crab spiders (Thomisidae).
Those spiders which live on plants usually blend in with the plants they live on. Grass dwellers have elongated bodies, bark spiders resemble bark and flower spiders, such as the Crab spiders, change colour to blend in with their flower.
Did you know? When a spider moves, there are always 4 legs on the surface and 4 off it!
Reference: Professor Ansie Dippenaar-Schoeman
Purchace a copy of 'Spiders of Fernkloof Nature Reserve'' by Vic Hamilton-Attwell and Ansie Dippenaar-Schoeman - contact Vic 082 785 5145
