Crabs Crabs live in the ocean in reefs and other oceanic homes There are about 45,000 types crabs Some crabs live on land and others live in the water The crabs that live in the water have paddles on their back legs what makes them able to swim Crabs that live on land have eight walking legs which are on the back side When the female crab has baby crabs they come out in eggs When the female crab lays her eggs she puts them in water During the first stage, the crab is known as a zoea The zoea is very tiny and looks a lot like a shrimp The zoea usually feeds only on the larvae of oysters and starfish The zoea starts to shed the outer layer of its shell because it is getting big This is called molting When the crab enters its second stage of growing it is called megalops This means that it has large eyes The megalops also gets its claws and the appendages of an adult crab This shows that the crab is almost done growing During the final stage the crabs are full grown Coral crabs which are found in warmer parts of the tropical oceans get their food from coral polyps These are tiny animals which create coral reefs Ghost crabs and fiddler crabs eat mud and sand off the beach
Lobsters Lobsters live at the bottom of the ocean Lobsters eat smaller shrimp and coral reef animals Lobsters usually move around and hunt for food at night It was once thought that lobsters were scavengers and ate primarily dead things which includes fish crabs clams mussels sea urchins and sometimes even other lobsters Lobsters hide in sea weeds and rocky habitat that provide adequate food and shelter from predators adult lobsters live in deeper waters and may return seasonally to shallow warmer waters A female lobster mates primarily after she has shed her shell Female lobsters can carry live sperm for up to two years At any time she may decide to fertilize her 3,000 75,000 eggs The teeth of a lobster are in its stomach The stomach is located a very short distance from the mouth and the food is actually chewed in the stomach between three grinding surfaces that look like molar surfaces called the gastric mill
Millipeds Millipedes sometimes termed thousand legged worms have two pairs of legs on each body segment except the first few and the last Females in one Californian species typically have more 650 legs The millipede body is nearly circular in cross section Millipedes do not have a poisonous bite, but many protect themselves by offensive odors produced by stink glands some produce highly irritating compounds that can injure the skin or eyes of attackers They are widely distributed in temperate and warmer regions living in surface litter under stones or logs and in relatively humid surroundings They feed mostly on decaying vegetation although some will consume decaying animal food
Centipedes Centipedes are the most familiar of the myriapodous arthropods which consist of five groups of arthropods that had a separate origin from other arthropods Centipedes live under logs and in wood also under rocks Centipedes are widely distributed in temperate and tropical lands living in the soil or surface litter and under logs or rocks The largest species Scolopendra gigantea may reach 12 in The flattened body is divided into a head and a trunk composed of segments The head bears long antennae jaw and two pairs of maxillae used for food handling the name centipede means hundred legged Larger centipedes can cause a painful bite but the poison is not powerful enough to cause death in humans Centipedes are chiefly nocturnal and predominantly carnivorous feeding on insects or other small arthropods though the largest species can kill small vertebrates Geophilomorpha and Scolopendromorpha produce clusters of eggs which are guarded while they develop
Horseshoe Crabs related to the spider sometimes called a king crab The heavy dark brown exoskeleton or carapace is domed and shaped like a horseshoe The body is divided into a broad flattened semicircular front part the prosoma a tapering middle part the opisthosoma and a pointed spiky tail like part the telson pincerlike chelicera that are used to crush worms and other invertebrates taken as food Five pairs of walking legs attached to the prosoma enable the animals to swim awkwardly or burrow through the sand or mud Horseshoe crabs first appeared in the Upper Silurian period and a number of fossil species have been described Five species still survive four of these are found along the Pacific coast of Asia The American species Limulus polyphemus is common along the Atlantic coast from Nova Scotia to Florida It lives in shallow water preferring soft or sandy bottoms and reaches a maximum length of nearly 2 ft Horseshoe crabs are considered living fossils
Arachinids Spiders are arachnids Their bodies are in two parts the head and the abdomen Most spiders have eight eyes but some have six four or two Many spiders trap their food in webs. Not all spiders make webs Some are hunters Some spiders dig homes under the ground Some spiders can live most of their lives under water in bubble webs Some spiders have claws at the end of each leg Spiders live in all sorts of environments Scorpions and spiders are predators of other insects Arachnids evolved about 500 million years ago That's about 50, 000 times longer than humans have been on earth All spiders have fangs and most kinds have poison glands use their fangs and poison glands to capture their food The life span of arachnids in temperate areas is a single season There are more than 30,000 kinds of spiders
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