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ARTHROPODS
Characteristics of arthropods
There are more than a million different species of arthropods, making them the largest group of animals. The word arthropods mean “jointed foot”. Thejointed appendages of arthropods can include legs, antennae, claws, and pincers. Arthropod appendages are adapted for moving about, capturing prey, feeding, mating, and sensing their environment; arthropodsalso have bilateral symmetry, segmented bodies, an exoskeleton, a body cavity, a digestive system with two openings, and a nervous system. Most arthropod species have separate sexes and reproducesexually. Arthropods are adapted to living in almost every environment. They vary in size from microscopic dust mites to the large, Japanese spider crab.
EXOSKELETON: all arthropods have a hard, outercovering called an exoskeleton. It covers, supports, and protects the internal body and provides places for muscles to attach.
An exoskeleton cannot grow as the animal grows. From time to time, theexoskeleton is shed and replaced bay a new one in a process called molting
Insects
More species of insects exist than all other animal groups combined. More than 700,000 species of insects have beenclassified, and scientists identify more each year
HEAD: An insect´s head has a pair of antennae, eyes, and a mouth, the antennae are use for touch and smell, the eyes are simple or compound, simpleeyes detect light and darkness, compound eyes contain many lenses and can detect colors and movement.
THORAX: Three pairs of legs and one or two pairs of wings, if present, are attach to the thorax.Insects are the only invertebrate animals that can fly.
ABDOMEN: the abdomen has neither wings nor legs but it is where the reproductive structures are found. Females lay thousands of eggs, but only afraction of the eggs develop into adults. Instead, insects have openings called spiracles on the abdomen and thorax through which air enters and waste gases leave the insect´s body.
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