Their range extends from central California to the Gulf of Alaska. Sucking lice are small wingless external parasites that feed on blood. Antenna (plural antennae): Long, segmented appendages that are located behind the eyestalks Antennule (plural antennules):Shorter appendages located between and below the eyestalks; used to smell and taste Appendages: Five pairs of legs, including one pair with claws, three pairs of jointed walking legs, and one pair that is flat and used for swimming Sea spiders possess a tubular proboscis forward from the body trunk, at the end of which is the opening to the mouth. In some spiders, the chelicerae have teeth, which are used to macerate prey items to assist digestion by secreted enzymes. The head and thorax are joined together and are covered by a shell called a carapace. Dungeness crab belong to a group of animals called crustaceans meaning they have an exoskeleton or shell that protects their bodies. Hermit crabs are unique and entertaining pets. In general, arthropods have mouthparts for cutting, chewing, piercing, sucking, shredding, siphoning, and filtering. Taking It Further ... (tail), compound eyes, mouth, chelicerae and other legs. Chelicerates comprise four classes of arthropod, with similar gross morphology but defining differences: Class Xiphosura (horseshoe crabs); class Eurypterida (the extinct eurypterids); class Arachnida (spiders, scorpions, ticks and mites); and class Pycnogonida (sea spiders). The horseshoe crab gets its name from the shape of its head, which is rounded in shape just like the shoe of a horse. Activity 7: Hooray for Horseshoe Crabs 2. Mouth - The mouth is located at the front of the crab, near base of the eyestalks and the antennae. Place the crab back into the dish of water, watching its mouth field as you do. This article outlines the basic elements of four arthropod groups: insects, myriapods, crustaceans and chelicerates. Total Points. They have an interesting anatomy that helps explain many of their actions and behaviors. • Identify the horseshoe crab’s internal organs including the brain, heart, crop and gizzard, and mid-gut. Oesophagus: A short tube, moving upwards from the mouth and widens posteriorly to open in the stomach. Exoskeleton: the hard outer, protective layer which must be shed as the crab grows. Underside of a female showing the legs and book gills. In general, however, crustaceans possess paired mandibles with opposing biting and grinding surfaces. Three types of sucking lice infest humans: the body louse, Pediculus humanus humanus Linnaeus, also known as Pediculus humanus corporis; the head louse, Pediculus humanus capitis De Geer; and the crab louse or pubic louse, Pthirus pubis(Linnaeus). The preoral cavity so-formed contains paired mandibles and any maxillae which are present. The tip is a pointed fang, which has an opening from a venom gland. Live crab are cooked by steaming them for 15–18 minutes, or by boiling for approximately 10 minutes. They settle on the bottom of the ocean floor. After two to three weeks its new, soft shell fully hardens. Their body is divided into two sections. It is illegal to harvest female crabs. Stir in croutons, crab meat, diced red pepper, cheddar cheese, Old Bay, pepper and parsley. If the abdomen is narrow, it is a male. Today's Rank--0. While the crab’s new shell is soft it takes in water and expands, stretching its new skin. Beginning in September, crab will tend to be more filled out, meaning there is a higher percentage of quality meat. Most mouthparts represent modified, paired appendages, which in ancestral forms would have appeared more like legs than mouthparts. Dungeness crab prefer sandy bottom habitat. Mud Crab External Anatomy learn by taking a quiz; Online quiz to learn Mud Crab External Anatomy; Your Skills & Rank. It is closely related to the hermit crab and king crab. 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