Showing posts with label ARTHROPODS. Show all posts
Showing posts with label ARTHROPODS. Show all posts

Some dangerous South African spiders



1) Black button spider (Latrodectus indistictus): 

  • Black medium-sized spider
  • most have some form of orange-red markings on the dorsal side (top) of the abdomen, absent in some females. They never have any red markings on the ventral side (bottom) of the abdomen.
  • make a smooth, round whithish-yellow egg sac about 10mm in diameter. More than 1 egg is found in the web
  • one of the most dangerous spider in South Africa
  • venom is neurotoxic
  • bite is painful and produces symptoms within half an hour
2) Brown button spider (Latrodectus geometricus): 

  • show an hour-glass pattern on the ventral side of the abdomen
  • they vary in colour from light yellowish-brown, with geometric patterns on the dorsal side of the abdomen, to pitch black
  • normally found around human habitation
  • lay more than 1 egg, which are slightly smaller than the black widow eggs and are always spiky and irregular in shape
3) Sac spider (Clubionidae): 

  • have a black face appearance with the compact body in various shades of cream, light brown and yellow
  • have long legs with the hairs on the foot very dark brown to black
  • chelicerae are black, long and rather stout
  • most members of this family construct tubular or flat sacs of dense white silk, either open or closed at the ends, to use as a retreat
  • leaf-curling sac spiders make sacs in rolled-up leaves, in folded blades of grass or under loose bark
  • the long-legged sacs spiders that are often found in houses make a flattened, disc-shaped sac in the fold of curtains, behind or under objects. The sacs are papery and shiny and very tough. The egg sac is similar but smaller.
  • these spiders are aggressive and will bite at the slightest provocation.
  • bites that are painless are characterised by 2 bite marks about 6mm apart.
  • the venom is cytotoxic and within 24 hours the site becomes inflamed and swollen, and ulcerates after a few days.
  • the ulterative wound is very slow in healing and often becomes subject to secondary infection. Accompanying fever may be present and often with severe headaches.
4) Violin spider (Loxoscelidae): 

  • the colour varies from brick-brown to rich red-brown, with darker markings on the abdomen
  • they have a characteristic dark-brown to black violin-shaped marking on the carapace, hence the common name
  • the spider roams freely at night in search of prey
  • the venom is cytotoxic causing ulcerating wounds, often involving severe secondary infection
  • the resulting tissue damage leaves disfiguring scars that may require plastic surgery

5) Six-eyed crab spider (Sicariidae):

  • have a flattened body with thickish legs
  • the eyes are set in 3 pairs on the front of the flattened carapace
  • the legs are extended sideways and held close to the ground
  • the venom is cytotoxic, causing severe ulcerative wounds with tissue damage at all levels
  • it destroys the tissue structure in the vinicity of the bite as well as tissue thoughout the body causing internal haemorrhaging and necrosis

6) Small Baboon spider (Harpactirella lightfooti): 

  • is from the South-western Cape
  • small and more slender than the other baboon spiders
  • it lacks cheliceral scopula and the spinnerets are very long and protrude beyond the posterior end of the abdomen
  • venom is neurotoxic



Les Scorpions

On trouve plus de 130 espèces différentes de scorpions en Afrique du sud. 

Les 2 principales familles présentes sont les Scorpionidae et les Buthidae.

Les Scorpionidae ont une queue fine, de gros pédipalpes, et ne sont pas tellement venimeux. La piqûre est douloureuse cependant. Ils capturent leurs proies puis les immobilisent.

Les Buthidae ont une queue épaisse, de petits pédipalpes, et sont réellement venimeux. Ils sont très agressifs, toujours près à piquer, et le venin est neurotoxique. (voir araignées et venins).


SPIDERS

In South Africa, there are 64 different families of spiders which can be divided into 2 sub-orders: the Mygalomorphs and the Araneomorphs.

Characteristics of Mygalomorphs:
  • 2 pairs of booklungs
  • chelicerae that strike forwards and downwards
  • medium to large
  • sedentary groundwellers
  • ex: Beboon spider, Trapdoor spider
Characteristics of Araneomorphs
  • 1 pair of booklungs
  • chelicerae that work against each other from side to side
  • web-making
  • ex: Golden orb-web spider
Attention: Spiders, Scorpions and Snakes are venomous: they inject venom into other animals (# poisonous: ingested, eaten).

Venomous spider

The factors that could influence the severity of a spider bite are:
  • the amount of venom
  • the sight of the bite (more effective on facial)
  • the age, the health, the allergies of the victim
NEUROTOXIC venom:

It affects the neuromuscular synapses and causes heart palpitations, difficulty breathing, raised blood pressure, severe pains in the chest and abdomen, an extreme anxiety.

The genus Latrodectus is medically important.
Only the bite of a Black button spider need a immediate medical attention.

CYTOTOXIC venom:

It affects the cellular tissues around the site of the bite and sometimes the tissues throughout the body. It is painless, the first symptome is a inflamed red bump; but severe symptomes develop slowly, it becomes painfull, ulcerating into a large surface lesion.

Families Loxoscelidae (Violin spiders); Clubionidae (Sac spiders); Sicariidae (Six-eyed crab spider).
The Sicarius are the most poisonous cytotoxin that is known is South Africa.


Insectes


Les insectes sont la Classe la plus nombreuse des animaux vivant sur terre, 
et représente 75 % des variétés d'espèces dans le monde.
 L'Afrique du Sud possède environ 29 Ordres d'insectes et plus de 800 espèces différentes!