Insects are small terrestrial invertebrates that have an exoskeleton and six legs. They do not have an internal skeletal system, thus the need for an exoskeleton (hard outer shell). They are the largest animal group on earth. It is thought that they make up more than 90% of all animal species on earth.
The body of an insect has 3 sections: a head, a thorax, and an abdomen. Their two compound eyes and antennae are located on their heads. The wings (usually two pairs) and legs (3 sets of jointed legs) are located on the thorax. The abdomen of the insect houses their stomach, heart, and excretory system (which they use to get rid of waste). Stinging insects such as bees and wasps also have a stinger located on the abdomen.
There are 4 classes of cheliceriformes: Eurypterids, Merostomata, Pycnogonida, and Arachnida.
Eurypterids are a class of water scorpions. However, they are all extinct. They used to be found in freshwater bodies of water and were predators in their environment.
A well-known type of Merostomata would be the horseshoe crab. They are found in shallow coastal waters. Their larvae look similar to trilobites (which lived during the prehistoric period and are now extinct).
An example of a Pycnogonida is a water spider. The Pycnogonida is different from other cheliceriformes in that they have 4 pairs of walking legs, instead of 3. It is believed that their extra legs may be a segment of their body that has been duplicated.
Examples of Arachnida are spiders, mites, tics, and scorpions. They live on land, unlike the other types that all live in coastal waters.
Arthropods are a member of a diverse group of animals such as insects, scorpions, spiders, crustaceans, and centipedes. Arthropods have 5 distinguishable characteristics that set them apart from other animals; Exoskeletons, segmented bodies, jointed appendages, bilateral symmetry, and an open circulatory system.
Arthropods have no internal skeletal system. Instead, they have an exoskeleton made of chitin to protect them. Their bodies are segmented into sections. Some arthropods have sections, while others have hundreds. They have jointed appendages, which allow for flexibility and movement. The joints generally only bend in one direction. Bilateral symmetry means that their body can be divided into two sections from top to bottom and have two symmetrical pieces. The left side is symmetrical to the right. Arthropods do not have a network of veins. Instead, their blood is pumped though an open circulatory system called sinuses.
A mandibulate is an arthropod with a jaw. The name “mandibulata” literally means “mandibles” or “jaws”. This is a characteristic that defines all members of this arthropod group. All arthropods fall into one of two groups; mandibulates or Chelicerates. The jaws on the mandibulata are used for chewing. It is a prehistoric adaptation for survival. The mandibles are located on the third or fourth head segment of the arthropod.
The most well-known mandibulates are ants. Ants also have pincers in front of their jaws for grasping and pulling in food. Their jaws give them the ability to crush strong food items, such as pieces of nuts, berries, and even other animals.
All Mandibulates have 3 distinct body regions (head, thorax, and abdomen) and a pair of antennae.
A Chelicerate is an arthropod that that has no distinct head region. Some of the most well-known Chelicerates are sea spiders, arachnids, and horseshoe crabs.
Chelicerates all originated as marine animals, most likely during the Cambrian period. Fossil records of Chelicerates have been found as long as 445 million years ago. The only prehistoric species remaining are 4 species of xiphosurans, or horseshoe crabs and about 1,300 species of pycnogonids, also known as sea spiders.
All Chelicerates have jointed limbs and segmented bodies. Chelicerates have chelicerae (which is where they get their name from), that are visible in front of their heads. In most species, they are the pincers located in front of the mouth. In spiders, they are the fangs.
Taeniasis is an infection that is caused by a tapeworm (type of parasite). The tapeworm is a small organism that attaches itself to a host (another living animal) to survive. Taeniasis is specifically an intestinal infection caused by eating beef or pork that has been contaminated with tapeworm.
Many people with Taeniasis will not have any symptoms. However, if they do, symptoms may include pain, blockage of the intestines, digestive problems, and unexplained weight loss. Some people who have been infected will complain of irritation in the perianal area (area around the anus). This is because worm segments or eggs being expelled from the body in the stool cause an irritation as they exit.
For those that have no symptoms, they become aware they have been infected because they see worms, worm segments, or eggs in their stool, which can take between 8 to 14 weeks to develop after being infected.
D. Echinoderms That is the answer for the question