Even people have never actually seen a tarantula, they are afraid of it; Mostly because of the fact that it is huge, hairy and looks venomous. However, it should be noted that these animals pose no danger to human beings. Apart from causing a lot of pain, their venom is no worse than a wasp sting. Tarantulas are classified in the family of spiders known as hairy mygalomorphs. One fact that is most interesting about this family of spiders is that although they have been around for millions of years, they have not evolved much in all that time. There are about 700 species of tarantulas in the world today.
Physical characteristics
The tarantulas are arthropods and as such, their physical characteristics are somewhat similar. They are invertebrates and use their exoskeleton muscles for support. It consists of two main parts the cephalothorax and the abdomen. These two are connected by the pedicel.
The size of a tarantula varies greatly from being as small as a fingernail to being as large as a dinner plate. The size depends on its age and the extension of its legs. Their size also varies from species to species. Some are as small as 2.5centimeters and others are as large as 10 centimeters. The span of their legs can be anywhere between 8 and 30 centimeters. This leg span is usually determined by measuring the tip of the back leg to the tip of the front leg on the opposite side. The tarantula can weigh up to 85 grams. The largest known tarantula, the goliath birdeater weighs 170 grams. Male tarantulas are longer and have a greater girth than female tarantulas. Their fang has a maximum height of 1.5 inches.
The color of the tarantula also varies depending on its species and habitat. Most of the tarantulas in north America are brown while those in other parts of the world are cobalt blue, black with white stripes, others have a green prosoma, an orange abdomen and metallic blue legs.
They have eight legs all of which are attached to their prosoma. It has two chelicerae which carry their fangs. These chelicerae are located right below its eyes, directly in front of the mouth and are double segmented. The fangs are extensions of the chelicerae and inject venom into an animal when the tarantula bites. They are also used to masticate. The fangs, much like a pocket knife and its handle, can be extended in preparation for a bite or can be folded back toward the chelicerae.
There are also two six segment appendage that are connected to the thorax known as the pedipalpi. They extend to both sides of the chelicerae. The pedipalpi have sharp plated that are somehow jagged. They are mostly used to crush or cut food. Like with all other spiders, the terminal part of the pedipalpi, in males, acts as its reproductive system. They have four pairs of legs and two pairs of appendages. There are seven segments on each leg; claw, tarsus and pretarsus, tibia, patella femur, trochanter and the coxa from the claw to the prosoma.
On the claw, the tarantula has a group of hairs known as the scopula which help it during climbing. The fifth pair of the pedipalps is used to grip prey, feel and in mature males, they are used in mating. Spiders have flexible tube like structures that it uses to produce silk. These tube like structures are known as spinnerets. The tarantula has two or four spinnerets. It is believed that tarantulas have spigots that produce the silk on their feet.
Its brain is located at the bottom of the inner prosoma. It has sensory organs called setae which mainly consist of spines and hairs. It uses these to perceive its environment. Its keenest sensory organs are its eyes. While hunting however, it mostly relies upon vibrations made by its prey’s movements. The setae can be used to sense a number of things including the direction of the wind and maybe even sound. They respond to the presence of certain chemicals. They have small eyes that are arranged in two rows of four. Some tarantula species have better vision than some species.
They have two sets of lungs. The first pair is located at the lower front part of the abdomen. The second is at the far back of the abdomen. There are tiny slits on each side of the abdomen where air enters. Each lung has more than 15 folded tissues. These are arranged like the pages of a book. These tissues have numerous blood vessels. These organs do not just absorb air, they also absorb moisture from the humid air in their surroundings.
The blood of the tarantula is unique not just physically but its chemical components too. It has a copper based protein present. Unlike the blood in mammals, its blood is not enclosed in blood cells. It is not true blood. It is a liquid form of hemolymph. Its heart which is located at the top of the opisthosoma, is a long tube. It is coordinated by the muscle cells. It has passages known as sinuses which the heart uses to pump the hemolymph to all parts of the body.
Hunting
The hunting habits of tarantulas vary depending on the species. While some hunt on trees, others hunt on the ground. They produce silk which they use to line the walls of their burrows and even make a door. Their diet mainly consists of arthropods and insects. Their main strength during hunting is their element of surprise. Bigger tarantulas kill larger animals such as lizards, birds and some snakes.
Predators
Tarantulas also have their own predators. Although they may appear dangerous, like most animals, they are not at the top of the food chain. Their number one predator is a family of wasps known as pompilidae. These wasps are also called tarantula hawks because they specialize in the tracking and killing of tarantulas. They kill them by stinging their sides and taking advantage of the thin membranes. The sting paralyses the spider allowing the wasp to drag it into its burrow. It then deposits an egg in the tarantula’s abdomen and seals it in the burrow. Once this is done, the tarantula then flies off and looks for more prey. When the larva hatches, it feeds on the spider.
Human beings are also considered predators because tarantulas are a delicacy for some people. Usually, tarantulas are roasted over open fire to remove the hairs. They are then served and eaten. To protect themselves from predators, tarantulas have fine hairs that cover the abdomen. These fine hairs are mainly for irritating predators. These fine hairs are barbed and can be fatal to animals such as rodents. One should prevent their eyes and respiratory organs from coming into contact with these hairs. Some people develop extreme itching when they come in contact with these hairs.
Fascinating Tarantula Images
Digestive system
The tarantula’s digestive system begins with the mouth which is located at the front part of the prosoma. Its mouth is shaped like a straw. It is only used to suck liquids. When captures a prey that has many solid parts, the spider has to crush it and coat it with digestive juices. These juices are secreted by the chelicerae. Its stomach is a large tube that runs from its mouth to its butt. At the prosoma, the tube widens and becomes a sucking stomach. This strong sucking force created by the stomach allows the tarantula to suck its prey from its mouth into the intestines. Once the food gets into the intestines, it is broken down into smaller particles that are absorbed into its bloodstream.
Life cycle
Tarantulas, like other spiders also go through molting. Molting is a process where they shed their exoskeleton body in order to grow. This may happen several times a year as the tarantula grows to maturity. You can tell that molting is about to happen when the exoskeleton becomes darker than it usually is. They take two to five years to reach maturity. However some species take as long as 10 years to get to adulthood. Once the male reaches adulthood, it will immediately look for a female to mate with because it only has about one to two years to live. Female tarantulas can live for as long as 40 years. They can also survive on water alone for up to two years.
Reproduction
Once the male spider reaches maturity, it will form a mat. It will then release a large quantity of semen on to this mat by rubbing its abdomen. It keeps the semen viable by dipping its pedipalps in the semen. Once it spots a female, they will exchange signals and find out whether they are of the same species. If they are of the same species, the signals lull the female into a receptive state. The male then approaches and transfers the semen into her body by inserting its pedipalps into her lower abdomen. Once this is done, the male will leave hurriedly before the female regains her appetite because she may be aggressive and may even eat the male. Depending on its species, she may deposit anywhere between 50 to 2000 eggs in an egg sac where they will stay for 6 to 8 weeks. She will turn the egg sac frequently. This helps keep the eggs from deforming due to being in one position for too long.
