Tarantula Anatomy:

I have included two diagrams for both the dorsal (Top) and ventral (underneath) views of a tarantula. Please click on the relevant links below to see the diagrams.

 

Ventral View

 

 

Tarantulas like all spiders have an exoskeleton that is hard in some places yet supple in others. The exoskeleton protects and encases the spiders internal organs. Since this exoskeleton is hard unlike skin which stretches and grows, the spider must moult or shed its skin in order to grow. Prior to moulting your spider will refuse to eat for around one/two weeks, this is normal and should be no cause for concern. Your spider will spin a web like mat upon the substrate where it will then proceed to turnover on its back. It may take several hours for your tarantula to shed its skin completely and it may remain still for several hours after whilst still remaining upside down, be aware that your spider is not dead and this is normal. Do not poke or prod your spider during this time, as disturbance could prove fatal.

DURING THE MOULTING PERIOD IT IS IMPORTANT NOT TO TOUCH OR DISTURB YOUR SPIDER AS THIS IS THE TIME WHEN IT IS AT ITS MOST VULNERABLE, AFTER MOULTING YOUR SPIDERS EXOSKELETON WILL BE EXTREMELY SOFT AND IS PRONE TO DAMAGE. DO NOT FEED YOUR SPIDER FOR SEVERAL DAYS AS THE INTRODUCTION OF INSECTS DURING THIS TIME COULD CAUSE INJURY TO YOUR PET.

Unlike insects, spiders have two main body parts instead of three. These are the cephalothorax (head and thorax combined) at the front (anterior), and the abdomen at the rear (posterior). They also have four pairs of legs each of which has seven segments, and chelicerae instead of mandibles. The chelicerae are to what the fangs are attached and also contain the poison glands. The tarantula uses these to dig its burrow. Tarantulas have vertically moving fangs, unlike most spiders which have horizontal movement. The tarantula also has another pair of appendages as well as its legs. These are the pedipalps, which are adjacent to the chelicerae and look like short legs. The tarantula uses these to grab its prey and also to move objects around. At the end of each leg tiny claws are found which aid the spider and help it to cling when climbing.

The cephalothorax is joined to the abdomen by thin narrow tissue known as the pedicel. The top of the cephalothorax is known as the carapace on which are mounted the eight eyes just behind the chelicerae raised inside a small turret, the tarantula has four eyes for daytime vision and four for night-time. Located inside the cephalothorax is the brain and also the spiders sucking stomach. Within the abdomen are located the reproductive organs and the heart. At the rear of the abdomen are found the spinnerets used to produce silk. Tarantulas use silk to make their webs for many different purposes. Arboreal (tree dwelling) tarantulas use silk to make a nest in which they sit. Burrowing species may line their burrows with it, wrap up their prey or eggs, and a tarantula will spin a bed of silk in order to lie upon during moulting. Tarantulas unlike most spiders have muscles which can independently control the movement of the spinnerets. Underneath the spider located on the abdomen can be seen the genital opening and also the four book lung slits. The spider excretes waste via the anus found near the spinnerets.

Tarantulas have very small mouths. They eat their prey by firstly administering venom which paralyses the prey and then slowly dissolves all of the internal structure of the insect. The spider then proceeds to suck out the dissolved solution until nothing is left except a small dehydrated pellet of the insects outer skin.

Covering the spiders whole body are hairs which are very sensitive to touch and send signals to the brain via nerves. Tarantulas do not have ears as such, however it has been suggested that some spiders may be able to sense vibrations since some tarantulas do have the ability to produce sound.