Tarantula Anatomy

Cephalothorax: The combined head and thorax of theraphosidae. Connected to the cephalothorax are the legs, the pedipalps, the chelicerae and the abdomen. Also called prosoma.

Abdomen: The rear section of theraphosidae. Also called opisthosoma.

Chelicerae: Or jaws. Contains the fangs and venom glands (which produce the venom). The chelicerae are used to inject the venom (through the fangs), to chew the food (by using a liquid that makes a fluid of the prey) and to dig or move soil.

Pedipalps: Appendages next to the chelicerae. They are not used for walking but for holding/locating stuff. Also in males they contain palpal organs that are used for mating. Unlike a leg the pedipalps have no metatarsal segment (and therefor 7 instead of 8 segments).

Ocella: theraphosidae have 8 eyes on the front of the cephalothorax. They have very poor eyesight.

Fovea: A small groove in the 'center' of the carapace. This is the part which marks the internal attachment of the leg muscles and the stomach’s suction muscles. Some species of theraphosidae have a horn on this spot.

Pedicel: This part connects the cephalothorax with the abdomen.

Spinnerets: Appendages (2 pairs) on the rear of the abdomen that are used to guide and place the silk. Silk can be used to detect prey, to hold the solved prey items together, to construct a burrow or to make an egg sack.

Urticating hairs: Hairs found on theraphosidae species from the 'New World'. These barbed hairs serve as defense. They can be extremely irritating.



Scopula pads: A brush of hairs on the underside of the tarsus and metatarsus. These help to give a better grip on almost every surface.

Pedipalps: Appendages next to the chelicerae.

Chelicerae: Or jaws. Contains the fangs and venom glands (which produce the venom).

Fangs: The fangs are used to inject the venom, to meal the food and to dig or move soil.

Sternum: Oval shaped plate between the coxae.

Coxa: The coxa is where the leg and the cephalothorax come together. It is the first segment of the leg.

Maxilla: Coxae of the palps, part of the mouth.

Labrum: Upper 'lip'.

Labium: Lower 'lip', under the mouth cavity.

Book lungs: Respiration organ. Theraphosidae species have 2 pair of book lungs, the anterior book lungs located next to the epigastric furrow, and the posterior book lungs. These contain hollow leaf-like structures through which the blood flows.

Epigynial plate: Plate above the Epigastric furrow.

Epigastric furrow: The opening to the spermathecae (for females).

Urticating hairs: Hairs found on theraphosidae species from the 'New World'. These barbed hairs serve as defense.

Spinnerets: Appendages (4) on the rear of the abdomen that are used to guide and place the silk.



Tibial spurs: Or mating spurs. A pair of hooks on the tibia section of the first set of legs of a male species obtained after his last molt to adulthood. They are used to hold back the females fangs during mating. Some species of theraphosidae lack these mating spurs.

Palpal bulps: Copulating bulbs present on the tip of the mature male pedipalps. The male will deposit his sperm in these bulbs by using a sperm web. After the palpal bulps are 'loaded' the male can insert the sperm from the bulbs into the spermathecae of a female specimen.

Claws: Found at the end of each tarsus. In combination with the scopula pads it enables good climbing on smooth vertical surfaces.

Pedipalps: Appendages next to the chelicerae.

Chelicerae: Or jaws. Contains the fangs and venom glands (which produce the venom).

Ocella: Theraphosidae have 8 eyes on the front of the cephalothorax.

Fovea: A small groove in the 'center' of the carapace.

Pedicel: This part connects the cephalothorax with the abdomen.



Uterus externus: Only found in females. This is a transparent piece of skin that connects to the uterus internus. This is an important feature in determining the sex of a tarantula from its shed skin. It's the point where the sperm and the eggs come into contact.

Spermathecae: Only found in females. These are the sacks in which sperm from the male is received and stored. The picture shows an example of a paired structure. Spermathecae come in a variety of shapes depending on the species. Sperm that has been stored in the spermathecae will be lost after a moult because the female also shed the spermathecae. There are some species that lack spermathecae.

Carapace: Hard outer covering (or shield) on the dorsal section of the cephalothorax.

Trochanter: Second segment of the leg or pedipalp between the femur and coxa. Also called thigh ring.

Femur: The third segment of the leg or pedipalp between the trochanter and patella. Also called thigh.

Patella: The fourth segment of the leg or pedipalp between the femur and tibia. Also called knee.

Tibia: The fifth segment of the leg or pedipalp after the patella. Also called shin.

Metatarsus: The sixth segment of the leg between the tibia and tarsus. Also called middle foot.

Tarsus: The last segment of the leg (after the metatarsus) or pedipalp (after the tibia). Also called foot.

Booklungs: Respiration organ.

Chelicerae: Or jaws. Contains the fangs and venom glands (which produce the venom).





Reference: Alan Mommerency - [You must be registered and logged in to see this link.]