Elizabeth, a Licensed Massage Therapist, has a Master's in Zoology from North Carolina State, one in GIS from Florida State University, and a Bachelor's in Biology from Eastern Michigan University. She has taught college level Physical Science and Biology.
Acari are Arachnids
You may already know that while they sometimes look similar, spiders are not insects. Spiders are in the class Arachnida, of which they are the largest order. But Arachnida also consists of other animals such as scorpions and harvestmen. Arachnida also contains the subclass Acari, which are the ticks and mites, and the focus of this lesson.
Before we get into acarids, let's take a step back to see where they fit into the larger scheme of things. We now know that acarids are arachnids. Arachnids are in the subphylum Chelicerata, which also consists of horseshoe crabs and sea spiders. Chelicerates get their name from their chelicerae, which are fang- or claw-like appendages that help the animal grasp and pinch.
From Chelicerata we move up to the phylum Arthropoda, which is enormous. In fact, it is the largest phylum in the kingdom of Animalia. Insects, lobsters, crabs, spiders, centipedes, and of course, ticks and mites, make up this group.
Heading back down to Acari, we find that they are divided into two superorders: Parasitiformes, which has more than 15,000 described species, and Acariformes, with more than 40,000 species.
Ticks and Mites
With about 55,000 species of acarids, there is an entire field of study devoted to them called Acarology. And while ticks and mites are often confused for one another, they are different. Additionally, there are different kinds of ticks and there are different kinds of mites.
Acarids range in size from only a few hundred micrometers to a few centimeters (when fully engorged). They live on land and also in aquatic environments. Some are parasitic, meaning they feed on other animals like us! Others are harmless, like the dust mites that live in your house and eat the dead skin cells you leave behind.
When you look at a spider you'll see two body segments - the cephalothorax, which is a fused head and thorax, and the abdomen. Ticks and mites generally do not have this type of segmentation, though their mouth parts sometimes look like a separate segment. Like other arachnids, acarids have four pairs of legs. Some have eyes while others are completely blind and depend on other sensory structures to guide them.
Both ticks and mites can transmit disease to plants and animals. Mange, Lyme, Rocky Mountain spotted fever, hemorrhagic fever, and tick-borne encephalitis are just a few examples. Ticks and mites may also just be a pain - dust mites can cause house-dust allergies, and some mites serve as intermediate hosts for other pests, such as tapeworm parasites. And if you've ever had chiggers, you know how awful these itchy mites can be!
The Acari, or ticks and mites, are a subclass of the class Arachnida. Arachnida also contains spiders, scorpions, and harvestmen. Arachnids are in the subphylum Chelicerata, which is in the largest phylum of the animal kingdom, Arthropoda. With over 55,000 described species, the subclass Acari is further broken down into two superorders, Parasitiformes and Acariformes. The study of this diverse group of animals is called Acarology.
Acarids range from the microscopic to a few centimeters. They have four pairs of legs, no body segmentation, and some are blind and navigate using other sensory organs. Some acarids are parasitic and feed off of other animals, some are quite mobile while others are sedentary, and some even clean up after us in our own homes. Both ticks and mites can transmit disease, and some even serve as an intermediate host for other parasites.
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