Maybe you think they’re creepy crawly or maybe you think they’re fascinating creatures. Regardless of which, spiders live with us, though not often apparent. It can help us appreciate them and be less afraid if we know more about them. And if there are ones to have a healthy respect for, educating ourselves on which those are is a good plan.
A few quick facts to start:
- Approximately 41,000 species of spiders have been described thus far.
- About 900 call Texas home.
- Spiders are placed in the Class Arachnida which also includes scorpions, mites, ticks, and seven other taxonomic orders.
- The lifespan of a spider can vary from a few months up to twenty-five years for female tarantulas!
- All spiders are strictly carnivorous.
- Most spiders are solitary although a few live communally and cooperate in obtaining prey.
Spiders possess two main body parts: the prosoma (front part or cephalothorax) and the opisthosoma (rear part or abdomen). Four pairs of walking legs are attached to the prosoma. A pair of pedipalps are in front of the first pair of legs. These leglike appendages are used for manipulating prey.
In the male spider, the pedipalps are used as an intromittent sex organ. In front of the pedipalps are the chelicerae which are used for defense, subduing prey, and grasping things. The fangs are housed in a special groove in the chelicerae.
Although most spiders have eight eyes, some have only two, four, or six.
Some cave dwelling spiders have lost their eyes completely. Most spiders have fairly poor vision; however, some can see quite well. Jumping spiders, which actively stalk their prey, have excellent vision. They also take the award for cutest spider as they will turn their furry heads to peer intently at you. Spiders breathe by way of tubular tracheae and book lungs. Book lungs (which resemble the pages of a book) are located on the ventral side of the opisthosoma and allow for air exchange.
Spiders must molt in order to grow. The old cuticle separates from the new and about a week later the old skin is shed. Spiders are extremely vulnerable right after molting and until the new cuticle hardens.
Silk is produced in glands at the rear of the abdomen. The glands end in spigots at the end of three pairs of spinnerets. Spider silk is incredibly strong. It is used for snares as well as draglines and egg cases. Female spiders have a special gland specifically for producing egg sac silk. The spiral orb web is the most well known type of web. One of our most eye catching natives, the yellow garden spider (Argiope aurantia), can be seen resting in an orb web with a zigzag in the center.
Written by Judith Bryja, Houston Zoo Herpetology Supervisor