The opiliones are called "daddy longlegs" (Chinese for "long-legged daddy") and sometimes "harvestman" (Chinese for "harvester"), which is a blind spider in the arachnid order under the arthropod phylum. Blind spiders are often mistaken for spiders. Indeed, blind spiders have some of the same characteristics as spiders: they, like spiders, belong to the arachnid order; like all arachnids, they have eight legs; and tend to jump like spiders; blind spiders are often seen where we often see spiders; and the Chinese names "spider" and "blind spider" have the word "spider" in them. So these two types of animals are often confused. In fact, blind spiders are more like scorpions in the arachnid order than spiders.
I. Arachnids
In addition to various spiders, the animals of the arachnids include blind spiders, scorpions, mites and ticks, which are certainly not spiders. In fact, arachnids are not insects. Insects are animals with six legs, four wings, or a pair of antennae, and apatranths do not have any of these characteristics. To date, there are about 50,000 species of arachnids that have been discovered and described worldwide, making it the largest of the crayfish subphylum. The extant species of Arachnids can be divided into 2 suborders and 11 orders.
The bodies of arachnids are divided into two segments: the precursor (cephalothorax) and the posterior body (abdomen). The precursor consists of 6 segments, usually wrapped in a hard dorsal carapace on the back, with one or more web plates on the ventral surface, or covered by the basal segments of the appendages. The posterior is often composed of 12 solitary segments, and with the exception of scorpions, most of the abdomen is no longer divided into two distinct parts, and the abdomen of the mites heals with the precursors and becomes a whole. No more than 12 single eyes. The hindquarters of spiders are connected to their precursors by means of a ventral stalk. The posterior body usually has no appendages. dioecism. Most are carnivorous. Breathe in the lungs or trachea, some of which are both.
Second, the general characteristics of blind spiders
Blind spiders generally do not exceed 5 mm in length, but can be up to 10 cm or longer. There is only one pair of eyes, and the vision is very poor. Feed on small arthropods, snails and plant scraps. Blind spiders are widely distributed throughout the world. They usually live on tree trunks, in grass, under rocks, or in corners. The feet of the carrionic blind spider are slender, and the upper jaws and tentacles are not significantly specialized; the feet of predatory blind spiders are short and thick, and the upper jaws and tentacles are specialized as pincer-like structures that can be used for predation.
Third, the difference between blind spiders and spiders
All blind spiders belong to the order Opiliones. Blind spiders are different from spiders in terms of the number of eyes, body size, structure of sexual organs, and defense mechanisms. The head, thorax, and abdomen of the blind spider heal into a thoracic cavity; the spider has a distinctly constricted waist between the cephalothorax and abdomen. Blind spiders have only 2 eyes, while spiders usually have 8 eyes.
Unlike spiders, blind spiders do not produce silk, so they do not form webs, let alone use silk webs to catch prey. If you occasionally look at a blind spider in a spider's web, don't mistake it for where it lives and that the web is its hunting tool. It may be dying on that web, trying to escape the spider that is about to eat it, fighting for the last glimmer of hope for survival.
Also, blind spiders are not poisonous animals. They have no fangs and no venom glands. With the exception of a few species, most spiders produce venom.
Fourth, the special adaptive changes of blind spiders
Blind spiders emit a foul odor when threatened because they have defensive stink glands, and blind spiders have been observed to use odorous substances released by stink glands to drive away predators. Many species of blind spiders are very good at disguising themselves. During the day, they usually hide in cracks, and when they are disturbed, they usually curl up and stay motionless for a few minutes there pretending to be dead, which is an effective way for blind spiders to escape danger.
The self-cutting behavior of blind spiders (autotomy). Many people, especially children, when they see a blind spider, they want to grab its long foot with their hands, but as soon as they catch its foot, or even just touch one of its feet, it will immediately disconnect and abandon the foot and run away. In order to escape the capture of predators or other dangerous situations, they will adopt a strategy of giving up the small and seeking the big, voluntarily deciding that it is enough to save their lives. But the most unfortunate thing for an adult blind spider is that if it breaks off a whole growing foot, it will be lost forever, and it will not grow again. If you are still in the nymph stage, there may be hope that the severed foot will grow back.
The foot of the blind spider is not only its important motor organ, but also its important sensory nerve distribution point. Through its feet, the blind spider can feel vibrations, smells and tastes, receive a lot of information from the outside world and transmit it to the central nervous system. If the blind spider's foot is broken, it may limit its ability to recognize and understand the outside world.
Fifth, the mating behavior of blind spiders
Spiders indirectly transfer sperm to females, but blind spiders are different. Blind spiders have elaborate mating rituals and special organs that place sperm directly into the female's body. In some species of blind spiders, male blind spiders that come to courtmate and mate are sneaky, some people call them "beta males", they will disguise themselves as female blind spiders, sneak up on it, and then implant their sperm into the female without the female blind spider's knowledge.