ämblikulaadseid

Ämblikulaadseid refers to the Chelicerata subphylum, a group of arthropods that includes arachnids, horseshoe crabs, and sea spiders. These creatures are characterized by their lack of antennae and the presence of chelicerae, which are pincer-like or fang-like appendages near the mouth, used for feeding. The body of a chelicerate is typically divided into two main parts: the prosoma (cephalothorax) and the opisthosoma (abdomen).

The prosoma houses the eyes, mouthparts, and legs. Most chelicerates have simple eyes, and the number varies greatly among different groups. The legs are generally attached to the prosoma, with four pairs being common in many species. The opisthosoma contains the digestive, reproductive, and respiratory organs. Respiration in terrestrial chelicerates often occurs through book lungs or tracheae, while aquatic forms may have gills.

Chelicerata is a diverse subphylum with a long evolutionary history. Arachnida is the largest class within Chelicerata, encompassing spiders, scorpions, mites, and ticks. Horseshoe crabs, though marine and ancient in appearance, are also chelicerates. Sea spiders are another marine group belonging to this subphylum. Their ecological roles are varied, ranging from predators and herbivores to parasites and detritivores.