Classes of Chelicerata

Arachnida-Animals that belong to this class are spiders, scorpions, mites, and ticks the largest and most broad class of Chelicerata and a very important one spider's being the most well-known for the wrong reasons they are crucial to the environment they contribute to pollination and seed dispersal they are also very important for pest population without them there would be a mass famine due to spiders eating so many of the insects that destroy crops such as flies, beetles, cockroaches, and locust scorpions also do this eating beetles and cockroaches mites while harmful can help with pest population and soil health tick are also very harmful but they help with overpopulation and an essential food source although I would agree they do more harm than good transmitting all kinds of diseases, viruses, and parasites 

Xiphosura-The only animal that belongs to this class are horseshoe crabs they are living fossils after 300 million years with hardly any change they have ten eyes but can only see light and dark they usually only swim to get away from predators but when they do their upside down and their blood is blue and is used in medicine they live in shallow coastal areas and they feed on invertebrates, crustaceans, and algae and their mouth is on the bottom in between their legs they can also range from 3.5-33.5in with females being larger and I've been lucky to be able pet one see them get feed and had their handler tell me about them

Pycnogonida-The only animal that belongs to this class are Sea spiders a marine arthropod resembling spiders hence the name they have small, reduced bodies, long hinged legs, and an unusual probiscis their sizes range from 1cm to 70cm they live in the Pacific Ocean, Mediterranean Sea, Carribean sea, and the seas of both the north and south pole typically found on rocks and coral to camouflage they eat invertebrates such as coral, clams, and marine worms they do this by piercing their prey with their leg then draining them of their blood and fluids with their probiscis and there are over 1300 different types 

Eurypterida-The only animal that belongs to this class are sea scorpions and is the only totally extinct class of Chelicerata these were marine arthropods and one the largest arthropods before their extinction approximately 251.9 million years ago during the Permian-Triassic extinction event the largest type of sea scorpion the Jaekelopterus Rhenaniae was believed to be able to reach about 8.2ft in length but most average out at 13-23cm their anterior appendages acted like oars and some had dual respiratory systems allowing for short time on land

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