Spiders are an incredibly diverse and fascinating group of animals. As with other venomous creatures, many people tend to be overly concerned about them. Only two of the 900 species in Texas are truly dangerous and both of them are quite shy and retiring. Bites do occur but they are rare and usually the result of accidental contact.
Except for one taxonomic family, all spiders possess venom glands. By far, the majority of spiders are not dangerous to people although allergic reactions can occur as with wasp or bee stings. The only spiders of medical significance in Texas are the Black widow (Latrodectus mactans) and the Brown recluse (Loxosceles recluse).
The name Black widow is actually a misnomer as the action implied rarely occurs. Black widows have a potent neurotoxic venom which can be quite dangerous to debilitated persons and young children. An antivenom is available for Black widow bites if deemed necessary. Brown recluse venom is a necrotoxin which can cause tissue damage.
After a male’s last molt he is sexually mature and will spend the rest of his life seeking mates, oblivious to everything else including food. Most male spiders only live for a few months after their maturing molts. The male constructs a special sperm web onto which he deposits sperm from his genital opening. The sperm is then taken up into the pedipalps to be later placed in the genital opening of the female. After a few weeks the female will construct a silken cocoon in which to lay her eggs which can number from a few to several thousand.
Many spiders guard their egg cases. Some spiders even exhibit parental care. A wolf spider female will open the egg sac and allow the spiderlings to ride on her back for a few weeks. There is even a spider that will regurgitate food for her offspring.
We come close to many more spiders than we will ever know because of their size and habits. These seemingly primitive mechanical creatures actually prove very interesting if one spends a little time observing them.
Written by Judith Bryja, Houston Zoo Herpetology Supervisor
